Objectives: Taraxasterol is the active ingredient of Taraxacum officinale which has been used in traditional medicine for its several therapeutic effects. This study aims first to evaluate the potential spinal/supraspinal and peripheral/visceral antinociceptive effect of taraxasterol and then to investigate the contribution of GABAergic, opioidergic systems, and KATP channels to its antinociceptive effect. Methods: The antinociceptive activity of taraxasterol (2.5, 5, and 10 mg/kg i.p.) was investigated with hot-plate, tail-immersion, and acetic acid-induced abdominal writhing tests (for supraspinal, spinal, peripheral/visceral pain evaluation, respectively) in BALB/c male mice, and percentage of possible maximum effect (MPE%) values were calculated. Mechanism of action studies were performed by pre-administering bicuculline, naloxone, and glibenclamide. Results: Taraxasterol increased the MPE% values in hot-plate and tail-immersion tests at 2.5, 5, and 10 mg/kg doses (P < 0.001) and decreased the mean number of writhes at 10 mg/kg in the abdominal writhing test (P < 0.05). Naloxone and bicuculline pre-administration reversed the antinociceptive effect of taraxasterol in hotplate and tail-immersion tests and it had no effect in the abdominal writhing test. Pre-administration of glibenclamide reversed the antinociceptive effect of taraxasterol in all tests. Conclusion: Our study is the first to show the involvement of GABAergic and opioidergic systems in the antinociceptive effect of taraxasterol in supraspinal and spinal pain tests, and KATP channels in tests evaluating supraspinal, spinal, and peripheral pain pathways. Taraxasterol is a potential new herbal medicine that can be used for pain control.

Placebo is a term to define physiologically inactive compounds used in treatment that causes physical and emotional changes. The placebo effect, driven by expectation and conditioning, plays a significant role in various conditions like pain, depression, and Parkinson’s disease, while the nocebo effect can hinder treatment outcomes. Understanding mechanisms such as neuromodulation and genetics has gained importance in modern medicine. This review aims to explore the clinical relevance of placebo responses, particularly in neuropsychiatric disorders, and their potential in personalized medicine. By integrating placebo research into healthcare, it highlights opportunities to enhance treatment efficacy, improve patient well-being, and reduce reliance on pharmacological interventions. A comprehensive literature search was conducted in PubMed, Scopus, and Google Scholar databases. Recent studies were reviewed to evaluate placebo effects, and the variability of the placebo response in neuropsychiatric disorders was summarized. Placebo effects significantly impact treatment outcomes across various conditions, including Parkinson’s disease, depression, pain syndromes, and epilepsy. The mechanisms involve neurobiological and psychological factors, with evidence suggesting that placebo interventions can modulate neurotransmitter activity and improve patient well-being. Integrating placebo research into clinical practice may enhance treatment outcomes, reduce drug dependency, and support personalized medicine by tailoring interventions to individual placebo responsiveness. Understanding placebo and nocebo mechanisms can optimize therapeutic strategies while minimizing unnecessary pharmacological treatments.

BackgroundThe endocannabinoid system plays important roles in various systems, including the genitourinary system; however, its mechanism of action is not fully understood.ObjectivesThis study aimed to investigate the direct relaxant effects of anandamide and its possible mechanisms in isolated rat bladder and vas deferens tissues.MethodsTwenty-one adult male Wistar albino rats were used. Bladder and vas deferens (prostatic and epididymal portions) tissues were mounted in 10 mL of organ baths. Relaxation responses to anandamide were recorded at 3 and 10 mu M concentrations. After the rest period, the procedures were repeated in the presence of cannabinoid (CB) and vanilloid receptor antagonists, various potassium channel blockers, cyclo-oxygenase, and nitric oxide synthase inhibitors. In different tissues to investigate the Ca2+-channel antagonistic effect of anandamide, concentration-response curves to CaCl2 were obtained in the absence and presence of anandamide.ResultsAnandamide caused a significant relaxation response in the bladder and epididymal vas deferens tissues, but not in the prostatic portion. The effect of anandamide was antagonized in the presence of the CB1 antagonist AM251 or the non-selective potassium channel blocker tetraethylammonium in bladder tissue. In the epididymal vas deferens, anandamide significantly inhibited the calcium contraction responses, especially at high concentrations. The CB2 antagonist AM630 reversed this inhibition.ConclusionsThe results show that anandamide has a direct relaxant effect on the isolated rat bladder and epididymal vas deferens. Anandamide triggers different mechanisms in different types of tissues, and further studies are needed to elucidate the mechanism of action of anandamide.

Amaç: Farmakovijilans, advers ilaç reaksiyonları (AİR) başta olmak üzere ilaçla ilgili sorunların tespit edilmesi, yorumlanması ve önlenmesi ile ilgili bilimsel çalışmalardır. AİR bir ilaca karşı gelişen zararlı ve beklenmeyen cevap olarak tanımlanır ve artan mortalite ve morbidite oranları, iş gücü kaybı gibi ekonomik sonuçlar nedeniyle AİR’in saptanması ve takibi önemlidir. Bu çalışmada tıp fakültesi 4. 5. ve 6. sınıf öğrencilerinin; farmakovijilans ve AİR konusundaki farkındalığını, bilgi ve görüşlerini belirleyerek farmakovijilans uygulamalarına ilişkin görevlerine yeterince hazırlıklı olup olmadıklarının incelenmesi amaçlanmıştır. Yöntem ve Gereçler: Bu çalışma gözlemsel, kesitsel ve tanımlayıcı tipte 2022-23 tarihleri arasında Sağlık Bilimleri Üniversitesi Gülhane Tıp Fakültesinde yapılmıştır. Öğrencilere, çalışma hakkında bilgi verilerek, Microsoft Forms uygulaması üzerinden anketi doldurulmaları sağlanmıştır. Kullanılan anket ile tıp fakültesi öğrencilerinin demografik özelliklerini, farmakovijilans ve AİR’ye yönelik bilgilerini, tutumlarını ve uygulamalarını değerlendirilmiştir. Bulgular: Çalışmaya katılan öğrenci sayısı 338’dir. Öğrencilerin %70’i farmakovijilansın tanımına doğru cevap verirken, %38’i Türkiye’de bir Farmakovijilans Merkezi’nin (TÜFAM) olduğunu ve %58’i Türkiye’de AİR izlenmesinden sorumlu kurumunun TÜFAM olduğunu bilmiştir. Öğrencilerinin %87,2’si AİR bildiriminin gerekli olduğunu düşünürken %26’sı hastanede farmakovijilans irtibat noktasının olduğunu bilmektedir. Öğrencilerin %81.6’sı AİR bildiriminin profesyonel bir yükümlülük olduğunun farkındadır. Öğrencilerin %53,5’i farmakovijilansın tıp fakültesi eğitiminde ayrıntılı olarak ele alınması gerektiğini belirtirken yalnızca %14’ü farmakovijilansın tıp fakültesi eğitimi müfredatında yeterli şekilde yer aldığını belirtmektedir. Sonuç: Çalışmamızda tıp fakültesi öğrencilerinin farmakovijilansa yönelik bilgi, tutum ve uygulamalarında eksiklikler olduğu gösterilmiştir. Bu eksikliklerin giderilmesi için tıp fakültesi eğitim müfredatında farmakovijilans ve AİR bildirimi ile ilgili düzenlemelerin yapılması ve ilgili üniversitelerin farmakovijilans irtibat noktaları ve TÜFAM’ın bu konuda aktif rol oynaması önemlidir.

This study was designed to evaluate the box sale trends of insulin preparations and glucagon-like peptide-1 (Glp-1) analogs by their therapeutic categories in Turkey. Also, we aimed to project sale trends of these pharmaceuticals in next years. We analyzed the data before the covid-19 pandemic and made predictions based on these data. This study analyzed retail and hospital box sales of insulin preparations from 4 therapeutic categories (fast/short-acting, intermediate-acting, premix, long-acting) and Glp-1 analogs. Total box sales of the insulin preparations were increased by %13,30 in the period examined. While fast/short-acting and long-acting insulin box sales increased with a decreasing upward trend, intermediate-acting and premix insulin box sales decreased. Glp-1 analog sales increased rapidly in this period. Currently, newer pharmaceuticals have been entering Turkish market for diabetes treatment. Less insulin might be required if newer pharmaceuticals are more widely available in diabetes treatment. Also it will be useful to evaluate the effect of the pandemic on access to pharmaceuticals used in the treatment of chronic diseases in future studies.

Taurine is widely distributed at high concentrations in mammalian tissues, and it plays an important role in a wide range of biological effects including modulation of cardiovascular functions. This review summarizes the role of taurine in vascular tone and blood pressure modulation based on experimental and human studies. It is well established that supplementation of taurine prevents development of hypertension in several animal models and p.o. taurine administration reduces blood pressure in hypertensive patients. Both central and peripheral actions of taurine may be involved in its hypotensive effects. In isolated animal arteries, taurine exerts vasodilation through endothelium-dependent and independent mechanisms. Several studies showed that taurine relaxed various animal arteries through opening potassium channels. We have recently shown that taurine relaxes human internal mammary and radial arteries by opening large conductance Ca2+-activated K+ channels. To date, the molecular mechanism(s) involved in the vascular effects of taurine are largely unknown and require further investigation. Clarifying the mechanisms in which taurine affects the vascular system may facilitate the development of therapeutic and/or diet-based strategies to reduce the burden of vascular diseases.

AMAC: Gebelikte ilac kullanimi hem anne hem de fetus icin olumsuz etkiler olusturabilir. Ilac kullanimina bagli teratojenite risk degerlendirmesi bu etkileri azaltmak icin onemlidir. Bu calismada amacimiz klinigimize basvuran gebelerde en sik kullanilan ilaclari ve bunlara ait guncel bilgileri degerlendirmektir. GEREC VE YONTEMLER: Bu calismada 1 Ocak 2011- 31 Aralik 2016 tarihleri arasinda Tibbi Farmakoloji Anabilim dalina ilac kullanim oykusuyle basvuran gebeler retrospektif olarak degerlendirilmistir. Tum gebelerin bir kadin hastaliklari ve dogum uzmanin tarafindan gebeligi tibbi olarak kanitlanmistir. Gebelikte kullanilan ilaclar ‘Anatomic Therapeutic Chemical’ (ATC) siniflandirilmasi kodlarina gore siniflandirilmis, risk kategorisi olarak Amerika Birlesik Devletleri’nin Gida ve Ilac Dairesi ( FDA ) kategorileri kullanilmistir. BULGULAR: Calismada 109 gebe degerlendirilmistir. Gebelerin ortalama yasi 32 olup, %37,61’i 30-34 yas araligindadir. Gebelik sirasinda en sik kullanilan ilaclar kemoterapotikler (%13,02), antiinflamatuvar ve romatizmal ilaclar (%12,67), solunum sistemi ilaclari (%8,80), seks hormonlari ve modulatorleri (%8,45) ve gastrointestinal sistem ilaclaridir (%7,04). FDA kategorilerine gore ise kullanilan ilaclarin %49,3’u ‘C’ kategorisinde, %22,5’i ‘B’ kategorisinde, %14,4’u ‘X’ kategorisinde, %10,2’si ‘D’ kategorisinde ve %3,5’i ‘A’ kategorisinde yer almaktadir. Ayrica gebelerin %64’u birden fazla ilac kullanmis ve ortalama ilac kullanim sayisi 2,60’dir. SONUC: Gebeler teratojenite riski olan ilaclara yuksek ortanda maruz kalabilmektedir ve gerek ilac recete eden hekimlerin, gerekse ilaci kullanan dogurganlik cagindaki kadinlarin, kullanim oncesi mutlaka gebelik durumunu sorgulamasi gerekmektedir. Gebelik durumunda ise ilac seciminin mumkun olan en az risk tasiyan gruptan yapilmasi onem arz etmektedir. Daha uygun bir risk degerlendirmesi icin de mevcut siniflandirma yeterli gozukmemektedir.

Aims: The present study was designed to detect the phytochemical components of herbs and herbal teas that are used to improve maternal milk production by gas chromatography/mass spectrometry (GC/MS). Methods: The methanolic extracts were extracted by maceration method using rotary evaporator. The essential oils of herbs were obtained by Clevenger method.Results: The GC/MS analysis of the essential oils or the methanol extracts of the mix of herbal teas or herbs including Foeniculum vulgare, Pimpinella anisum, Trigonella foenum graceum, Urtica dioica, Nigella sativa were listed as several compounds in this article. Furthermore, the possible pharmacological effects of these components have been discussed according to the literature. Conclusions: The findings of this study will guide researchers about the pharmacological active ingredients of these herbs and herbal teas that may be used in the future for milk enhancing or other medical purposes.

Potassium (K+) ion channel activity is an important determinant of vascular tone by regulating cell membrane potential (MP). Activation of K+ channels leads to membrane hyperpolarization and subsequently vasodilatation, while inhibition of the channels causes membrane depolarization and then vasoconstriction. So far five distinct types of K+ channels have been identified in vascular smooth muscle cells (VSMCs): Ca+2-activated K+ channels (BKCa), voltage-dependent K+ channels (K-V), ATP-sensitive K+ channels (K-ATP), inward rectifier K+ channels (K-ir), and tandem two-pore K+ channels (K2P). The activity and expression of vascular K+ channels are changed during major vascular diseases such as hypertension, pulmonary hypertension, hypercholesterolemia, atherosclerosis, and diabetes mellitus. The defective function of K+ channels is commonly associated with impaired vascular responses and is likely to become as a result of changes in K+ channels during vascular diseases. Increased K+ channel function and expression may also help to compensate for increased abnormal vascular tone. There are many pharmacological and genotypic studies which were carried out on the subtypes of K+ channels expressed in variable amounts in different vascular beds. Modulation of K+ channel activity by molecular approaches and selective drug development may be a novel treatment modality for vascular dysfunction in the future. This review presents the basic properties, physiological functions, pathophysiological, and pharmacological roles of the five major classes of K+ channels that have been determined in VSMCs.

BACKGROUND:Propofol is an intravenous anesthetic that can be used for the induction and maintenance of anesthesia. In the present study, it was aimed to investigate the mechanism of vasodilator action of propofol in the rat aorta (RA). METHODS:The RA rings were suspended in isolated organ baths and tension was recorded isometrically. First, potassium chloride (KCl) and phenylephrine (PE) were added to organ baths to form precontraction. When the precontractions were stable, propofol (1, 10, and 100 μM) was added cumulatively to the baths. The antagonistic effect of propofol on KCl (45 mM), PE (1 μM), 5-hydroxytryptamine (5-HT) (30 μM), and calcium chloride (CaCl2) (10 μM to 10 mM) induced contractions in the vascular rings were investigated. Propofol-induced relaxations were also tested in the presence of the K+ channel inhibitors tetraethylammonium (TEA, 1 mM), glibenclamide (GLI, 10 μM), 4-aminopyridine (4-AP, 1 mM), and barium chloride (BaCl2, 30 μM). RESULTS:Preincubation with propofol (1, 10, and 100 μM) did not affect the basal tone but inhibited the contraction induced by KCl, PE, 5-HT, and CaCl2-induced contractions. Propofol-induced relaxation was not effected by 4-AP, GLI, and BaCl2. However, TEA inhibited propofol-induced relaxations significantly. CONCLUSIONS:The propofol induces relaxation in contracted RA and inhibits KCl, PE, 5-HT, and CaCl2-induced contractions. The results demonstrate that the mechanism of action of propofol-induced vasodilation in the RA may be related to large conductance Ca2+-activated K+ channel activation.

Dental resin curing blue light (BL) is frequently used during treatments in dental clinics. However, little is known about the influence of BL irradiation on pulpal blood vessels. The aim of the present study was to investigate the mechanism of effect of BL irradiation on vascular tone. Rat aorta (RA) rings were irradiated with a BL source in organ baths, and the responses were recorded isometrically. Effect of BL irradiation on phenylephrine (PE) -precontraction and acetylcholine (ACh) -induced relaxation after PE -precontraction were obtained and compared in BL -irradiated and control RA rings. Effect of 20 min preincubation with catalase (enzyme that breaks down hydrogene peroxide, 1200 u/ml) on PE -precontraced and BL-irradiated rings was also evaluated. Total oxidative stress (TOS) and total antioxidant capacity (TAC) in BL-irradiated and control RA preparations were measured with special assay kits and spectrophotometry. BL slightly decreased ACh -induced endothelium -dependent relaxations in PE (1 μM) -precontracted RA rings (n = 6, p > 0.05 vs. control). BL induced marked contraction 23.88 + 3.10% of PE (maximum contraction) in isolated RA ring segments precontracted with PE (p < 0.05 vs. control). The contractile effect of BL was inhibited by 1200 u/ml catalase (n = 6, p < 0.05 vs. control). BL irradiation increased the level of TOS in RA rings (n = 6, p < 0.05 vs. control). TAC levels were similar in BL-irradiated and control preparations. These results suggest that BL induces contraction in RA, and the mechanism of this effect may to be through release of hydrogen peroxide.

The vascular actions and mechanisms of taurine were investigated in the isolated human radial artery (RA). RA rings were suspended in isolated organ baths and tension was recorded isometrically. First, a precontraction was achieved by adding potassium chloride (KCl, 45 mM) or serotonin (5-hydroxytryptamine, 5-HT, 30 µM) to organ baths. When the precontractions were stable, taurine (20, 40, 80 mM) was added cumulatively. Antagonistic effect of taurine on calcium chloride (10 µM to 10 mM)-induced contractions was investigated. Taurine-induced relaxations were also tested in the presence of the K+ channel inhibitors tetraethylammonium (1 mM), glibenclamide (10 µM) and 4-aminopyridine (1 mM). Taurine did not affect the basal tone but inhibited the contraction induced by 5-HT and KCl. Calcium chloride-induced contractions were significantly inhibited in the presence of taurine (20, 40, 80 mM) (p<0.05). The relaxation to taurine was inhibited by tetraethylammonium (p<0.05). However, glibenclamide and 4-aminopyridine did not affect taurine-induced relaxations. Present experiments show that taurine inhibits 5-HT and KCl-induced contractions in RA, and suggest that large conductance Ca2+-activated K+ channels may be involved in taurine-induced relaxation of RA.

Human users of synthetic cannabinoids (SCBs) JWH-018 and JWH-073 typically smoke these drugs, but preclinical studies usually rely on injection for drug delivery. We used the cannabinoid tetrad and drug discrimination to compare in vivo effects of inhaled drugs with injected doses of these two SCBs, as well as with the phytocannabinoid Δ9-tetrahydrocannabinol (Δ9-THC). Mice inhaled various doses of Δ9-THC, JWH-018 or JWH-073, or were injected intraperitoneally (IP) with these same compounds. Rectal temperature, tail flick latency in response to radiant heat, horizontal bar catalepsy, and suppression of locomotor activity were assessed in each animal. In separate studies, mice were trained to discriminate Δ9-THC (IP) from saline, and tests were performed with inhaled or injected doses of the SCBs. Both SCBs elicited Δ9-THC-like effects across both routes of administration, and effects following inhalation were attenuated by pretreatment with the CB1 antagonist/inverse agonist rimonabant. No cataleptic effects were observed following inhalation, but all compounds induced catalepsy following injection. Injected JWH-018 and JWH-073 fully substituted for Δ9-THC, but substitution was partial (JWH-073) or required relatively higher doses (JWH-018) when drugs were inhaled. These studies demonstrate that the SCBs JWH-018 and JWH-073 elicit dose-dependent, CB1 receptor-mediated Δ9-THC-like effects in mice when delivered via inhalation or via injection. Across these routes of administration, differences in cataleptic effects and, perhaps, discriminative stimulus effects, may implicate the involvement of active metabolites of these compounds.

The cold binary fission of even–even 244–258Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. The favorable fragment combinations are obtained from the cold valley plot (plot of driving potential vs. mass number of fragments) and by calculating the yield for charge minimized fragments. It is found that for 244,246,248Cf isotopes highest yield is for the fragments with isotope of Pb (Z=82) as one fragment, whereas for 250Cf and 252Cf isotopes the highest yield is for the fragments with isotope of Hg (Z=80) as one fragment. In the case of 254,256,258Cf isotopes the highest yield is for the fragments with Sn (Z=50) as one fragment. Thus, the fragment combinations with maximum yield reveal the role of doubly magic and near doubly magic nuclei in binary fission. It is found that asymmetric splitting is favored for Cf isotopes with mass number A≤250 and symmetric splitting is favored for Cf isotopes with A>252. In the case of Cf isotope with A=252, there is an equal probability for asymmetric and symmetric splitting. The individual yields obtained for the cold fission of 252Cf isotope are compared with the experimental data taken from the γ-γ-γ coincidences technique using Gammasphere.

To evaluate whether or not the bladder function can be protected by supporting the detrusor with decorin levels during the fibrotic process.

Background and Aim: Bone marrow-derived mesenchymal stem cells (BM-MSCs) are one of the sources of adult stem cells being explored for potential use in repairing neurodegenerative disorders. In this study, it was aimed to investigate the useful effects of BM-MSCs therapy on the streptozotocin-induced neurodegeneration in rats. Materials and Methods: Adult female Wistar rats were bilaterally injected intra-cerebroventricularly with streptozotocin (3 mg/kg) for neurodegeneration. Water maze tests were used to monitor spatial learning and memory. One or two intravenous injections of BM-MSCs were administrated to rat via the tail veins. At the end of the study, all rats were sacrificed for histological evaluation and immunohistochemistry. Results: Streptozotocin group demonstrated a significant increase in escape latency in comparison with both control groups (Sham and Saline), whereas rats treated with BM-MSCs exhibited a decrease in escape latency in comparison with streptozotocin group. The percentage of time spent in the target quadrant and the mean number of platform crossings did not change in all the groups. BM-MSCs administration improved spatial learning but not memory. However, improvement in neuronal cells in hippocampal CA1 region was only observed in the rats treated with BM-MSCs twice as opposed to the rats treated with BM-MSCs once or with saline. Conclusions: In this study, mesenchymal stem cells therapy failed to improve the streptozotocin-induced neurodegeneration like Alzheimer’s disease in rats.

The use of polymers has revolutionized the biomedical industry ever since their discovery. Dental polymers, commonly known as “Dental Resins,” were first used in dentistry in 1839, and since then they are widely used especially in restorative dentistry for both cosmetic and functional purposes. A variety of different polymer materials – vinyl acrylics, epoxy resins, polyether, polysulfide, silicone, polycarbonates, polyacrylic acid, polystyrene, polyethylene, polyvinyl acetate – are used in dentistry. Typical applications of polymers in dentistry are impression materials, relining materials, temporary crown materials, denture base materials, obturation materials (endodontic treatment), and filling materials (composites, cements, adhesives). Many prostheses and implants made from polymers have been in use for the last three decades and there is a continuous search for more biologically inert and stronger polymer dental materials. Biocompatibility of dental polymers is an important clinical issue. The dental polymers that is to be used in the oral cavity should be harmless to all oral tissues—gingiva, mucosa, pulp, and bone. Furthermore, it should contain no toxic, leachable, or diffusible substance that can be absorbed into the circulatory system, causing systemic toxic responses, including teratogenic or carcinogenic effects. The material also should be free of agents that could elicit sensitization or an allergic response in a sensitized patient. Rarely, unintended side effects of dental polymers may occur as a result of toxic, irritative, or allergic reactions. These reactions may be local and/or systemic. Local reactions involve the gingiva, mucosal tissues, pulp, and hard tooth tissues, including excessive wear on opposing teeth from restorative materials. Systemic reactions are expressed generally as allergic skin reactions. The quantity of unconverted resinous monomers that remain after polymerization determines the cytotoxic effects of polymeric dental materials, such as light-cured methacrylate polymers. These monomers may alter the lipid layer of the cell membrane, which affects membrane permeability. They may also undergo hydrolysis, producing a water-soluble cytotoxic substance, methacrylic acid. Some monomers may also displace water in dentin and they are capable of diffusing rapidly through the dentin. Furthermore, they may reduce the rate of cellular proliferation and result in apoptosis, possibly as a response to DNA damage. Additionally, because the oral cavity is highly vascularized, the effect of dental polymers on vascular function can be relevant to clinical practice. Several experimental studies provided evidence for the marked vasodilating effect of dental polymers, which might impair pulpal healing by promoting hemorrhage. In accordance with existing standards, all dental polymers should pass primary tests (screening to indicate cellular response), secondary tests (evaluating tissue responses), and usage tests in animals before being evaluated clinically in humans. After a material has successfully passed the primary and secondary tests, it should be tested in humans to evaluate its performance and the favorable or unfavorable reactions that may present under normal clinical conditions. The aim of the current paper is to provide an overview of the current literature on toxicology of dental polymers and to give implications for possible improvements concerning their biocompatibility.

OBJECTIVE Taurine is an abundant amino acid that is widely distributed in human and animal tissues. Pharmacodynamic studies show that taurine has hypotensive and myocardial protective effects. Studies in isolated tissue baths show that taurine relaxes precontracted arteries. This study aimed to show the effects of taurine on human internal mammary artery (IMA) in vitro and to explain the mechanisms of its effects. METHODS The response in the IMA was recorded isometrically by a force displacement transducer in isolated organ baths. Taurine (20, 40, 80 mM) was added to organ baths after precontraction with KCl (45 mM) or serotonin (5-HT, 30 µM). Taurine-induced relaxations were also tested in the presence of the cyclooxygenase inhibitor indomethacin (10 µM), the nitric oxide synthase inhibitor L-NAME (100 µM), the large conductance Ca2+-activated K+ channel inhibitor tetraethylammonium (TEA, 1 mM), the ATP-sensitive K+ channel inhibitor glibenclamide (GLI, 10 µM), the voltage-sensitive K+ channel inhibitor 4-aminopyridine (4-AP, 1 mM) and the inward rectifier K+ channel inhibitor barium chloride (BaCl2, 30 µM). RESULTS Taurine did not affect the resting tone of IMA. However, it produced relaxation in the 5-HT and KCl -precontracted preparations. The relaxation to IMA was not affected by GLI, 4-AP, BaCl2, indomethacin and L-NAME. But, TEA inhibited taurine -induced relaxations significantly (p < 0.05). CONCLUSIONS The preincubation of IMA with taurine antagonized KCl and 5-HT induced contractions in a concentration dependent manner, while it did not affect the resting tone. The relaxations to taurine were significantly antagonized by pretreatment with TEA. These results suggest that mechanism of vasodilator effect of taurine in IMA may be the activation of large conductance Ca2+-activated K+ channels.