The small arteries and the arterioles contribute substantially to the hydrodynamic resistance in the circulation. In some vascular beds, up to 80% of the pressure drop in the circulation occurs proximal to the capillaries. Also the distribution of the pressure drop between small arteries and arterioles varies between different vascular beds, but a substantial part of it is mediated by arteries with diameters larger than 50 μm. The structure of the small arteries and arterioles is of substantial importance for the resistance they produce, and the ratio between the thickness of the media wall and the lumen diameter is an important determinant of the effect on resistance of a given level of smooth muscle activation. This ratio is increased in small arteries from patients with hypertension. In both untreated and treated patients, the ratio has prognostic significance, and it appears to be an important aim of treatment to normalize the ratio. Also the tone of small arteries, determined by the activation of the smooth muscle cells, plays a key role in determining resistance. Smooth muscle cell activation is dependent on the intracellular Ca2+ concentration but also the sensitivity of the contractile machinery to Ca2+. Most small arteries and arterioles have an oscillation of tone, which is referred to as vasomotion. Vasomotion is dependent on a cellular oscillator and is a result of synchronization of the oscillatory contraction of the smooth muscle cells. One such pathway involves a Ca2+ activated, cGMP-dependent Cl− conductance. The physiological or pathophysiological consequence of vasomotion is unknown.

Although the historical bases for graduate training in the United Kingdom (UK) and Scandinavia both stem from the original concept developed by von Humboldt, and both award a ‘PhD degree', their paths have diverged. There are thus significant differences in the manner in which graduate training is organised. To analyse these differences, two UK graduate programmes (School of Medicine, Cardiff University; Institute of Integrative Biology, University of Liverpool) and two Scandinavian graduate schools (Faculty of Medicine and Dentistry, University of Bergen; Karolinska Institutet, Stockholm) completed a Self‐evaluation questionnaire developed by Organisation of PhD Education in Biomedicine and Health Sciences in the European System (ORPHEUS)). Analysis of the completed questionnaires shows differences concerning requirements for admission, the training content of PhD programmes, the format of the PhD thesis, how the thesis is assessed and the financial model. All programmes recognise that PhD training should prepare for employment both inside and outside of academia, with emphasis on transferable skills training. However, the analysis reveals some fundamental differences in the direction of graduate programmes in the UK and Scandinavia. In the UK, graduate programmes are directed primarily towards teaching PhD students to do research, with considerable focus on practical techniques. In Scandinavia, the focus is on managing projects and publishing papers. To some extent, the differences lead to a lack of full recognition of each other's theses as a basis for doing a postdoc. This paper describes the basis for these differences and compares the two approaches and points to areas in which there is, or might be, convergence.

Professor Paul M. Vanhoutte One of the world's leading pharmacologists, Paul M. Vanhoutte, died due to sequelae after an accidental fall. Although he had been seriously ill for a couple of years, his sudden death was unexpected and a shock to his family, friends and his many colleagues worldwide. Paul was born in Belgium and spanning nearly 60 years, he had an amazing scientific and professional career in public universities and in the private sector in five different continents. He obtained his Bachelor, Master of Science and Medical degrees at the University of Gent and his PhD at the University of Antwerp. He became an assistant at the University of Gent 1969-1971 and a research associate at the Mayo Clinic 1972-1973. Back in Belgium at the University of Antwerp, he was the first associate professor, then full professor and head of the Department of Pharmacology 1973-1981. He moved back to the Mayo Clinic to become a professor of physiology and pharmacology from 1981 to 1989 and subsequently Baylor College of Medicine in Houston Texas as a professor of medicine, pharmacology and physiology and a director of the Center for Experimental Therapeutics from 1989 to 1995. He then returned to Europe to become vice-president of research and development and director of discovery research at the Institute de Recherche Internationale Servier in Paris between 1992 and 2002. From 2003 to 2006, he was distinguished visiting professor and director/founder of the Biopharmaceutical Development Centre, at the Faculty of Medicine, University of Hong Kong. From 2006 to 2011, he was the head of the Department of Pharmacology and Pharmacy at the University of Hong Kong; from 2009 to 2015, he was a chair professor, and since 2015 until his death he was a permanent visiting professor in the same department. Since 2003, he held a part-time position of professor at the Faculty of Health Sciences at the University of Southern Denmark in Odense. He was a visiting professor at the National University of Rwanda (1967), the Polish Academy of Sciences (1979), Chonbuk National University in Jeonju in South-Korea 2013-2016 and King Saud University in Riyadh, Saudi Arabia 2013-2015. He was also an honorary professor at the Peking Union Medical College (Beijing), the Institute of Materia Medica of Beijing, the Ocean University of Qingdao, the Second Military Medical University in Shanghai and the Shanghai Institute of Materia Medica. At his death, he was still iconic visiting professor at the University of Malaya in Kuala Lumpur and a visiting professor at the University of Zurich. Paul was a member of the Academia Europea, the Académie Nationale de Pharmacie in Paris and the two Belgian Academies of Medicine and an honorary member of the Brazilian Academy of Medicine. He was a member of the American Association of Physicians, the American Society of Physiology, the American Heart Association (Fellow), the American Society for Clinical Investigation (Emeritus), the American College of Cardiology (Fellow), the American College of Angiology (Fellow), the American Society for Pharmacology and Experimental Therapeutics, the Belgian Society for Physiology and Pharmacology and the French Pharmacological Society. He was a member and past president of the Hong Kong Pharmacology Society. He was an honorary member or fellow of the Physiological Society in London, the British Pharmacological Society, the Chinese Pharmacological Society, the German Society of Angiology, the Société Française de Cardiologie and the European Society of Cardiology. He was the founder and past president of both the Serotonin Club (renamed as ‘International Society for Serotonin Research’) and of the Asian Society of Vascular Biology. From 1989 to 2007, he was the Editor-in-Chief of the Journal of Cardiovascular Pharmacology. He was Associate Editor of the American Journal of Physiology (Heart and Circulatory Physiology), of News in Physiological Sciences and of the Journal of Vascular Medicine and Biology. He was a member of the editorial board of many scientific journals (eg Circulation, Circulation Research, Cardiovascular Research, Hypertension, Journal of Hypertension, American Journal of Physiology, Acta Sinica Pharmacologica, Journal of Pharmacology and Experimental Therapeutics). He was a member, and the chairman, of the Program Project Review Committee of the National Heart Blood and Lung Institute of the NIH (Bethesda, MD, USA). He chaired the IUPHAR Committee for Receptor Nomenclature from 1989 to 1998. He was the secretary general of the International Union of Basic and Clinical Pharmacology (IUPHAR) from 1998 to 2002 and President of the Union from 2002 to 2006. Paul wrote three theses. Paul received the Doctor Honoris Causa degree of the University of Gent in 2001, and honorary degrees from the universities of Antwerp, Montreal and Zurich in 2003, from the Royal Melbourne Institute of Technology in 2005, from the University Louis Pasteur in Strasbourg in 2006, from the Gr T. Popa University of Medicine and Pharmacy in Iasi, Romania, in 2009, from Monash University in Melbourne in 2012 and from the University of Southern Denmark in Odense in 2016. Named lectures in his honour have been created by the American Society for Experimental Pharmacology and Therapeutics and by the International Society for Serotonin Research. His major scientific contribution has been to appreciate and analyse the importance of endothelial cells in the control of the underlying vascular smooth muscle in vascular health and disease and to highlight the complexity of that regulation. He co-authored or edited 36 books and published nearly 700 original research papers and nearly 600 editorials, reviews or chapters in books, the most recent one being in Basic & Clinical Pharmacology & Toxicology in July 2019!.1 According to Web of Science (August 2019), his scientific papers have been cited nearly 63 000 times and his h-index was 121. Thus, he was a Highly Cited Researcher in three categories: biology and chemistry, pharmacology and in clinical medicine. Paul was an enormous help and a great support of the Danish Society for Pharmacology when we planned and organized the 16th World Congress on Basic and Clinical Pharmacology in Copenhagen in 2010. Paul was a frequent guest at the summer meetings of the Danish Cardiovascular Research Academy, Sandbjerg, Denmark. Also, at these meetings, Paul was dedicated in a gentle and constructive way in order to help and encourage young scientists as well as to educate and inspire his colleagues. More than this, Paul worked with and mentored hundreds, if not thousands of young, now senior, researchers, providing guidance and inspiration. His contribution to the discussions at conferences, symposia, workshops and laboratory meetings showed always a sharp mind with constructive and supportive critique. His global influence at the personal level on the development of pharmacology was incalculable. Indeed, it was probably these personal interactions that he most valued. In April 1966, Paul married Jacqueline Vandenberghe, and they had four children: Valerie, Jacqueline Jr, Paul Robert and Alexis and seven grand-children: Elina, Evita, Claire, Elio, Remi, Natalie and Katherine Emma. They have all lost a highly beloved husband, father and grandfather. We have lost a good friend, a very good colleague and a scientific role model. All honour to his memory.

Aim: Established essential hypertension (EH) is associated with increased arterial stiffness and peripheral resistance, but the extent of vascular changes in persons genetically predisposed for EH is uncertain. Methods: Participants from the Danish Hypertension Prevention Project (DHyPP) (having two hypertensive parents) (n = 95, 41±1 years, 53% males) were compared to available spouses (n = 45, age 41±1 years, 43% males). The subjects had measurements of ambulatory blood pressure (BP), left ventricular mass (LVM), pulse wave velocity (PWV), central BP and augmentation index (AIx) in addition to forearm resting and minimal resistance (Rrest and Rmin). Results: DHyPP subjects with and without spouses were comparable and the DHyPP cohort, as compared to spouses, had higher 24-hour mean BP (94±1 vs. 88±1 mmHg, P < 0.01), LVM (90±2 vs. 80±2 g/m2, P < 0.01), central systolic BP (119±2 vs. 111±2 mmHg, P < 0.01) and AIx (15.1±1.2 vs. 10.5±1.7%, P < 0.01), but similar values of carotid-femoral PWV (7.3±0.1 vs. 7.1±0.2 m/s), Rrest (51±2 vs. 51±3 mmHg/ml/min/100 ml) and log Rmin (0.57±0.02 vs. 0.55±0.02 mmHg/ml/min/100 ml). AIx, Rrest and Rmin were higher in female as compared to male DHyPP participants (P < 0.01 for all) and the same was true for AIx and Rmin among spouses (P < 0.05). Using multiple linear regression analysis adjusting for gender, age, body mass index, 24-hour BP, 24-hour sodium excretion and creatinine clearance, AIx remained elevated in DHyPP subjects (3.4% [0.18; 6.60], P = 0.039). Furthermore, AIx was linearly associated with Rrest and Rmin. Conclusion: Young to middle-aged individuals genetically predisposed for EH display increased AIx, while vascular stiffness and peripheral resistance are still normal.

The PhD degree was established in Berlin 200 years ago and has since spread across the whole world. While there is general agreement that the degree is awarded in recognition of successfully completed research training, there have been significant differences in the way doctoral training programs have developed in particular countries. There is, however, a clear global tendency to follow the programs currently used either in the United States or in Europe. To determine more clearly how US and European PhD programs are both similar and different, we have used a validated questionnaire to analyze biomedical PhD programs in four representative institutions at Vanderbilt University, University of Manitoba, Karolinska Institutet, and Graz Medical University. The analysis is based on 63 detailed questions concerning the research environment, outcomes, admission criteria, content of programs, mentoring (or supervising), the PhD thesis, assessment of the thesis, and PhD school structure. The results reveal that while there is considerable overlap in the aims and content of PhD programs, there are also considerable differences regarding the structure of PhD programs, mentoring and assessment of PhD theses. These differences are analyzed in detail in order to provide a foundation for discussion of their relative advantages and disadvantages, with a view to providing a platform for discussion of best practices. The results will be of importance in the continued development of global discussion about development of doctoral training.

Biomedical research is increasingly based on the efforts of PhD students. This talk will trace the development of the author’s research, and show how this experience can be used to optimize PhD training. The basis of the research has been that essential hypertension is associated with increased peripheral resistance due to narrowing of the small arteries and arterioles. The author’s PhD training ended in 1978 with development of a technique that enabled accurate measurement of the structure and function of small arteries. The technique was adopted by many laboratories world-wide, and also formed the basis for the author to establish a research group (with 22 PhD students over the years) that elucidated excitation-contraction properties and the morphology of small arteries, and how these were altered in essential hypertension. Vessels showed increased media:lumen ratio with inward eutrophic remodelling and limited functional changes. The remodelling was found to have prognostic consequences. The inward remodelling was found to be due to the vasoconstriction itself, mediated through multiple cellular pathways. The remodelling can be prevented by vasodilators and the results have had clinical effect. While this career path points to some success, it would unlikely happen in today’s academic environment in that the author’s PhD training took about 10 years. Through being head of the faculty graduate school and vice-president of the organization ORPHEUS (Organization for PhD education in Biomedicine and Health Sciences in the European System), the author has sought to establish procedures to ensure that today’s PhD students are able to prepare for successful careers – within or outside of academia – even within the normal 3–4 year time constraints.

Aim: Young individuals genetically predisposed for essential hypertension have increased renal vascular resistance. We evaluated whether 1 year of angiotensin II receptor blockade decreases afferent arteriolar resistance (RA) and induces a sustained blood pressure (BP) reduction during a 10-year follow-up period in offspring of parents both diagnosed with essential hypertension.Methods: Based on renal plasma flow (p-aminohippurate clearance) and glomerular filtration rate (Cr-51-EDTA clearance) RA was calculated according to the model originally established by Gomez. Following baseline measurements, the participants (n = 110, mean age 30 years) were randomly allocated to 12 months of treatment with either candesartan or placebo followed by repetition of measurements and withdrawal of medication. Four-hour ambulatory BP (ABP) was recorded at baseline, by end of active treatment and after 6 months, 1, 2, 3, 5, and 10 years. ABP was analyzed according to RA achieved at the end of active treatment.Results: Candesartan reduced RA by 14% (P<0.01). Ten years posttreatment systolic ABP increased by 2.1 mmHg (P = 0.04) and diastolic by 4.2 mmHg (P<0.01) compared with baseline, without any difference between treatment arms. A high posttreatment RA was associated with higher BP levels during follow-up, but long-term alterations in 24-h BP were similar in participants with low and high RA and not different between treatment arms.Conclusion: RA is associated with 24-h BP levels, but temporary lowering of BP and RA by candesartan does not prevent BP from increasing further. Prevention of hypertension appears not feasible by short-term inhibition of the rennin-angiotensin system in young adults.

Background and PurposeVasodilatation may contribute to the neuroprotective and vascular anti-remodelling effect of the tissue transglutaminase 2 (TG2) inhibitor cystamine. Here, we hypothesized that inhibition of TG2 followed by blockade of smooth muscle calcium entry and/or inhibition of Rho kinase underlies cystamine vasodilatation.Experimental ApproachWe used rat mesenteric small arteries and RT-PCR, immunoblotting, and measurements of isometric wall tension, intracellular Ca2+ ([Ca2+](i)), K+ currents (patch clamp), and phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1) and myosin regulatory light chain, in our experiments.Key ResultsRT-PCR and immunoblotting revealed expression of TG2 in mesenteric small arteries. Cystamine concentration-dependently inhibited responses to phenylephrine, 5-HT and U46619 and for extracellular potassium. Selective inhibitors of TG2, LDN 27129 and T101, also inhibited phenylephrine contraction. An inhibitor of PLC suppressed cystamine relaxation. Cystamine relaxed and reduced [Ca2+](i) in phenylephrine-contracted arteries. In potassium-contracted arteries, cystamine induced less relaxation without changing [Ca2+](i), and these relaxations were blocked by mitochondrial complex inhibitors. Blockers of K(v)7 channels, XE991 and linopirdine, inhibited cystamine relaxation and increases in voltage-dependent smooth muscle currents. Cystamine and the Rho kinase inhibitor Y27632 reduced basal MYPT1-Thr(855) phosphorylation, but only Y27632 reduced phenylephrine-induced increases in MYPT1-Thr(855) and myosin regulatory light chain phosphorylation.Conclusions and ImplicationsCystamine induced vasodilatation by inhibition of receptor-coupled TG2, leading to opening of K-v channels and reduction of intracellular calcium, and by activation of a pathway sensitive to inhibitors of the mitochondrial complexes I and III. Both pathways may contribute to the antihypertensive and neuroprotective effect of cystamine.

OBJECTIVE:Structural changes of small resistance arteries occur early in the disease process of essential hypertension and predict cardiovascular events in previously untreated patients. We investigated whether on-treatment small artery structure also identifies patients at elevated risk despite normalization of blood pressure (BP).METHODS:We conducted a long-term follow-up survey of cardiovascular events in 134 moderate-risk patients with 9-12 months of well treated essential hypertension. All participants underwent subcutaneous biopsies with determination of small artery structure in terms of media to lumen ratio (M : L) before and during treatment.RESULTS:After 9-12 months of treatment SBP was lowered from 164 ± 15 to 134 ± 14 mmHg (P < 0.01) and M : L reduced from 0.084 ± 0.028 to 0.075 ± 0.024 (P < 0.01). Mean follow-up hereafter was 15 years representing a total of 2035 years for the entire cohort. During this period 47 patients suffered a predefined cardiovascular event. For patients with on-treatment M : L above the mean value of the cohort (≥0.075), the hazard ratio was 2.14 [95% confidence interval (CI) 1.19-3.84, P = 0.01] and also those with M : L above mean +2SD of a normotensive population (≥0.098) had an elevated risk (hazard ratio 2.99, 95% CI 1.60-5.58, P < 0.01). Both results were adjusted for heart score (a 10-year mortality risk estimate integrating age, sex, smoking status, cholesterol level and SBP). Analysis of changes in M : L during treatment showed significantly higher event rates among patients with increased M : L and vice versa (hazard ratio 1.36 per 25% change, 95% CI 1.07-1.73, P = 0.013).CONCLUSION:On-treatment small artery structure identifies individuals still at increased cardiovascular risk despite long-term BP normalization and may be an additional target for therapy to prevent cardiovascular events.

The PhD, otherwise known as the doctor of philosophy or Dr. Phil., is an internationally recognized degree, indicating that the PhD graduate has received training in research under supervision. Traditionally, the PhD was the route to an academic career, with most successful PhD graduates receiving tenured university positions. However, over the past 2030years, and particularly the past 10years, the situation has changed dramatically. Governments in many countries have invested massively in PhD education, believing that trained researchers will contribute to the knowledge society', and thus increase the competitiveness of their countries in the future economies of the world. Thus, only a small fraction of PhD graduates now end up in academic research. Yet, the PhD remains a research degree, and indeed, institutions have become heavily dependent on PhD students for their research output. The situation has thus created a paradox. On the one hand, it has become essential for institutions to have many PhD students and for the research performed to be of the highest level. On the other hand, the careers of PhD students are not necessarily going to be directly related to the research performed during their PhD studies. The purpose of this article is to explore how this seeming paradox is being addressed in biomedicine and to show that far from being inconsistent that the two aspects are in fact complementary. The article is based on the author's experience as Head of Aarhus Graduate School of Health Sciences 20022011 and his work with graduate schools across Europe and internationally through the organization ORPHEUS.

Ethnopharmacological relevance: Tinospora crispa has been used in folkloric medicine for the control of blood pressure. We previously found that an extract of Tinospora crispa and its constituents effect the heart rate and blood pressure in anesthetized rats.Aim of the study: The aim was to investigate the effects and mechanisms of the Tinospora crispa extract and bioactive components on the rat isolated left atria.Materials and methods: Air-dried stems of Tinospora crispa were extracted with water, followed by partitioning with chloroform, ethyl acetate, and finally by n-butanol. The n-butanol soluble material was concentrated and dried under reduced pressure and lyophilized to obtain a crude powder (Tinospora crispa extract). The active components of Tinospora crispa extract were separated by column chromatography and preparative HPLC. The effects and mechanisms of the n-butanol extract and the bioactive purified components (adenine, uridine, adenosine, salsolinol, tyramine, higenamine, syringin, (-)-litcubinine, borapetoside A, borapetoside B, borapetoside D and borapetoside E) were studied in isolated left atria from normal and reserpinized rats.Results: Tinospora crispa extract caused an increase in the force of contraction of the electrical field stimulated left atrium. This effect was inhibited by propranolol, atenolol, ICI-118,551, phentolamine and atropine. The positive inotropic effect on the reserpenized isolated left atrium of the Tinospora crispa extract was significantly inhibited by propranolol, atenolol and ICI-118,551. Phentolamine, on the other hand, caused potentiation and the effect was inhibited when propranolol was also added. Higenamine caused an increase in the force of contraction of the electrical field stimulated left atrium and this effect was significantly inhibited by ICI-118,551 and atenolol but not by phentolamine. Reserpine did not significantly shift the concentration response curve (C R curve) of the inotropic effect of the higenamine. ICI-118,551 and atenolol caused a parallel shift of the C R curve to the right of about 8 and 33 fold, respectively. At low concentrations salsolinol caused a slight increase in the force of contraction of the left atrium, but at higher concentrations a decrease was observed. The negative inotropic effect of salsolinol was significantly inhibited by propranolol and atropine. In the reserpinized isolated left atrium, the negative inotropic effect of salsolinol was potentiated and again this effect was significantly inhibited by propranolol and atropine. Tyramine caused a positive inotropic effect, and this effect was inhibited by propranolol or by pretreatment of the rat with reserpine. Adenosine caused a negative inotropic effect, while uridine caused a slight positive inotropic effect on the left atrium. This effect was significantly inhibited by DPCPX.Conclusions: Crude extracs of Tinospora crispa exert a positive inotropic effect on the electrical field stimulated isolated left atria that results from the concerted action of 5 bioactive compounds: higenamine, salsolinol, tyramine, adenosine and uridine. Higenamine, salsolinol (at low concentration) and tyramine acted via the adrenergic receptors to increase the force of the atrial contraction, whereas a high concentration of salsolinol acted indirectly by stimulating the release of acetylcholine. Adenosine and uridine acted via the purinergic pathways to cause negative inotropic effects on the isolated left atria. (C) 2013 Elsevier Ireland Ltd. All rights reserved.

Background: Essential hypertension is characterized by small artery remodeling and increased systemic vascular resistance (SVR). We hypothesized that changes in SVR index (SVRI) were associated with measures of small artery structure as reflected by minimum coronary and forearm vascular resistance (C-Rmin and F-Rmin, respectively). Also, we investigated how F-Rmin is related to C-Rmin, coronary flow reserve (CFR), left ventricular mass index (LVMI) and blood pressure (BP). Method: Sixty-six never-treated patients with uncomplicated mild essential hypertension had the following measured at baseline: 24-h blood BP, LVMI, CFR and C-Rmin (echocardiography), F-Rmin (forearm plethysmography) and SVRI determined by a gas re-breathing method. After 6 months of antihypertensive therapy administered by the general practitioner, the patients returned for follow-up measurements. Results: Changes in SVRI did not correlate to changes in F-Rmin (r = 0.001, P = 0.98) or C-Rmin (r = 0.13, P = 0.39) but did correlate to changes in CFR (r = 0.30, P = 0.04). Further analysis was performed by assigning the patients into two groups according to the median of drop in F-Rmin. When adjusted in a multivariate model, changes in F-Rmin (−8.1 ± 3.2%) were significantly associated with changes in C-Rmin (−9.3 ± 4.9%) and LVMI (−6.9 ± 1.7%) (P < 0.01), but not to either 24-h BP, SVRI or CFR. Conclusion: The results show that changes in neither BP nor SVRI reflected changes in minimum vascular resistance. However, changes in the forearm and coronary microcirculation occurred in parallel. Moreover, we demonstrated that neither BP nor SVRI reduction can predict changes in microvascular structure in hypertension. Thus, direct measurements of microvascular structure are needed to determine whether improvement is obtained.

We have investigated effects and mechanisms responsible for the activity of 3, 5, 7, 3′, 4′-pentamethoxyflavone (PMF) on isolated human cavernosum. PMF is the major flavone isolated from Kaempferia parviflora claimed to act as an aphrodisiac. PMF caused relaxation of phenylephrine precontracted human cavernosal strips, and this effect was slightly inhibited by NG-nitro-l-arginine, a nitric oxide synthase inhibitor, but not by ODQ (soluble guanylate cyclase inhibitor), TEA (tetraethylammonium, blocker of voltage-dependent K+ channels) or glybenclamide (blocker of ATP-dependent K+ channels). PMF did not significantly inhibit the relaxant activity of glyceryltrinitrate or acetylcholine on human cavernosal strips precontracted with phenylephrine. In contrast, sildenafil (phosphodiesterase inhibitor) potentiated the relaxant activity of glyceryl trinitrate but not of acetylcholine. In normal Krebs solution with nifedipine (blocker of l-type Ca2+ channels), or in Ca2+-free Krebs solution, PMF caused a further inhibition of human cavernosum contracted with phenylephrine. In human cavernosum treated with thapsigargin (inhibitor of sarcoplasmic reticulum Ca2+-ATPase) in Ca2+-free medium, PMF suppressed the concentration–response curve of human cavernosum to phenylephrine and a further suppression was found when SKF-96365 (a blocker of store-operated Ca2+ channels and Y-27632 (inhibitor of Rho-kinase)), but not nifedipine, were added sequentially. Thus, PMF had only a weak effect on the release of nitric oxide, and had no effect as a KATP- or KCa channel opener, a phosphodiesterase inhibitor, a store-operated Ca2+ channel blocker or a Rho-kinase inhibitor. Therefore, these studies suggest that PMF causes relaxation of human cavernosum through voltage-dependent Ca2+ channels and other mechanisms associated with calcium mobilization.

Ethnopharmacological relevance: Tinospora crispa has been used in folkloric medicine for the control of blood pressure. We previously found that an extract of Tinospora crispa stems decreased the mean arterial blood pressure (MAP) with a transient decrease, followed by an increase in the heart rate (HR) in rats.Aim of the study: To identify the active components of the Tinospora crispa extract and investigate the mechanisms of action on blood pressure and heart rate in anesthetized rats.Materials and methods: The active components of Tinospora crispa extract were separated by column chromatography and a preparative HPLC. The effects and mechanisms of the active compounds on blood pressure and heart rate were studied in anesthetized, normal and reserpinized rats in vivo.Results: 5 active compounds: adenosine, uridine, salsolinol, higenamine and tyramine were isolated. Adenosine decreased MAP and HR and this effect was inhibited by DMPX (A(2A) adenosine receptor antagonist). Uridine increased MAP and decreased HR and this was inhibited by suramin but not by DMPX. Salsolinol decreased the MAP and HR and this was inhibited by phentolamine but not by ICI-118,551 (beta(2)-adrenoceptor antagonist) or atropine. In reserpinized rats, salsolinol had a hypertensive effect that was inhibited by prazosin and phentolamine, but not by atenolol, and caused an increase in HR that was inhibited by atenolol, but not by prazosin or phentolamine. Higenamine decreased the MAP with an increase in HR. The hypotensive effect was inhibited by ICI-118,551 or atenolol, whereas the increase in HR was not inhibited by ICI-118,551. Atenolol inhibited the increase in HR at a small dosage of higenamine but potentiated it at a higher dosage. In reserpinized rats, a small dosage of higenamine tended to potentiate the effect but at a higher dosage it caused inhibition. ICI-118,551 significantly inhibited this hypotensive effect. Tyramine caused an increase in MAP and HR and these effects almost disappeared in reserpinized rats.Conclusions: The results demonstrate that these 5 compounds from Tinospora crispa acted in concert on the cardiovascular system of anesthetized rats. Salsolinol, tyramine and higenamine acted via the adrenoreceptors, whereas uridine and adenosine acted via the purinergic adenosine A(2) and P-2 receptors to decrease blood pressure with a transient decrease of HR followed by an increase. (C) 2012 Elsevier Ireland Ltd. All rights reserved.