A great number of milk-derived peptides have been shown to exhibit angiotensin converting enzyme (ACE) inhibitory properties and thus potential utility in the regulation of blood pressure. The present work aimed to investigate the effects of 2 milk trypsin hydrolysates from alpha(S1)- and alpha(S2)-casein (CH1 and CH2, respectively) on ACE activity evaluated in human umbilical vein endothelial cells (HUVEC) in vitro, rat aortic tissues ex vivo, and renovascular hypertensive rat in vivo. Incubation of HUVEC and rat aortic tissues with CH1 or CH2 induced a concentration-dependent inhibition of hydrolysis of the ACE substrate hippuryl-histidyl-leucine (HHL), the hydrolysates being much less potent than perindopril (an ACE inhibitor). However, in contrast to perindopril, CH1 and CH2 failed to modify angiotensin I-induced aortic ring vasoconstriction. The HPLC profiles of rat plasma after intragastric administration were variable among individuals but none of the observed peaks corresponded to peptides comprising CH1 or CH2 or to fragments of these peptides. During 4 wk of cardiovascular monitoring, in hydrolysate-fed renovascular hypertensive rats, systolic blood pressure weakly decreased compared with the control group. However, the CH1-fed hypertensive rats exhibited a decrease of heart rate during the nocturnal period of activity. To conclude, our results show that CH1 and CH2 inhibited ACE activity in HUVEC and rat aortic tissue but failed to antagonize the aortic-constricting effects of the natural agonist angiotensin I. Moreover, we demonstrated that CH1, to a greater extent than CH2, can slightly affect cardiovascular parameters although the ingested bioactive peptides could not be detected in the blood.

Nous avons montré précédemment qu'il existait une relation entre le développement du risque cardiométabolique (RCM) et le profil en acides gras (AG) des tissus insulino-sensibles. Nous avons également montré qu'un apport alimentaire d'AG polyinsaturés n-3 à longue chaîne (AGPI-LC, acides eicosapentaénoïque, EPA, et docosahexaénoïque, DHA), permet de limiter le RCM dans un modèle à bas bruit cardiovasculaire (rat fructose, Robbez Masson et al, J Nutr 2008). La présente étude vise à tester l'effet protecteur des AGPI-LC n-3 chez des animaux à plus fort bruit cardiovasculaire ; les rats spontanément hypertendus (SHR) également décrits comme modèle d'insulino-résistance (IR), permettent de modéliser le syndrome métabolique, en dehors du contexte d'obésité. Comparés à des rats WKY sous régime STD, des SHR répartis en 3 lots (n = 10) recevant soit un régime riche en AGPI-LC n-3 (LC3) ou en acide alpha-linolénique (ALA), ou ne contenant pas de n-3 (STD), ont été nourris pendant 10 semaines. L'IR a été évaluée par des tests de tolérance au glucose et à l'insuline, et la pression artérielle a été suivie par télémétrie. Les rats ont été sacrifiés après 10 semaines et les tissus collectés pour des analyses lipidiques membranaires. Nos résultats montrent que les SHR présentent une hyperinsulinémie à jeun par rapport au WKY et qu'ils secrètent plus d'insuline en réponse à un bolus de glucose pour revenir à une glycémie normale. Les SHR développent une IR (baisse de sensibilité à l'insuline). Les rats SHR présentent une hypertension artérielle (∼180mmHg), mais pas d'hypertriglycéridémie (TG). Les SHR présentent un profil en AG cardiaque spécifique de l'hypertrophie non corrélé à l'IR. Les régimes ALA et DHA améliorent le statut membranaire en n-3 (augmentation du DHA membranaire) et réduisent les TG circulants (FRCV). Toutefois seuls les LC3 ont permis de prévenir significativement le RCM en restaurant partiellement la sensibilité à l'insuline et en abaissant le niveau de pression systolique. Dans leur ensemble, ces résultats soulignent l'importance de la nutrition dans le syndrome métabolique en démontrant le rôle préventif d'une consommation régulière d'AGPI-LC n-3 sur le RCM.

Over the last decade, acute drug intoxications have been known to be a serious threat to the public health field. Nevertheless, only a few means of imperfect detoxication treatments have, unfortunately, been applied to date. This paper presents water-in-oil-in-water (w/o/w) reactive multiple emulsions (ME) as an efficient method of in vitro detoxication against Nivaquine, a drug widely accused of being used in suicide attempts. The detoxication efficiency of these emulsions is attributed to the use of an adequate extractant-trapping agent couple giving a good extraction yield. Interestingly, some prepared emulsions showed a Nivaquine extraction yield of about 85%. A series of studies was conducted to recognize the effect of the preparation protocol, the emulsion ingredients, especially the extractant-trapping agent couple, and the experimental conditions on the extraction output. The extraction yield increases with the concentration of the extractant and with the alcalinization of the extraction medium. Globally, these reactive multiple emulsions have shown to be stable and highly detoxifying against Nivaquine taken as a toxic molecule model. Moreover, the process of Nivaquine extraction by the extractant in the oily phase and its trapping in the internal aqueous phase has been elucidated and validated.

PURPOSEP-glycoprotein (P-gp) and cytochrome P450 (P450) affect drug disposition. Efavirenz (EFV) is an anti-HIV drug used in combination. Since most anti-HIV medications are substrate and modulators of P-gp and/or P450, we investigated the effects of EFV on intestinal P-gp and hepatic P450 function to predict drug interactions.METHODS(i) The effect of EFV on rat intestinal P-gp function was studied on everted gut sacs and in situ intestinal perfusion. EFV was orally administered (150 mg/kg) for 6 days. Then, rhodamine 123 was used as a P-gp substrate and verapamil as an inhibitor. P-gp function was evaluated by the difference between rhodamine 123 transport with and without verapamil. (ii) The effect of EFV on rat hepatic P450 metabolism was investigated using hepatic microsomes, prepared from rats pretreated or not with EFV.RESULTSIn everted gut sacs, P-gp function was not modified and in the in situ intestinal perfusion, rhodamine 123 clearance was not affected by EFV. Concentrations of the metabolites, 1-OH midazolam and 4-OH midazolam were higher in EFV pretreated rats than those in the control group.CONCLUSIONEFV should not modify intestinal absorption of co-administered substrates of P-gp, but could decrease plasma concentrations of co-administered drugs metabolized by P450.

Background. Lanthanum (La) carbonate has recently been proposed as an alternative, calcium- and aluminum-free phosphate binder for the treatment of hyperphosphatemia of chronic renal failure (CRF). However, the extent to which CRF enhances tissue La accumulation induced by oral La overload above that observed under conditions of normal renal function remains a matter of debate. In the present study, we examined this issue in two different rat models of CRFMethods. In a first series of experiments, adult male Sprague-Dawley rats received either a diet to which 0.3% adenine (wt% in feed) was added to induce CRF ("chemical CRF," N = 20), or a diet free of adenine (control, N = 16). In a second series of experiments, adult male Sprague-Dawley rats underwent 5/6 nephrectomy in a two-step procedure ("surgical CRF," N = 24). Half of all CRF and control rats were exposed to dietary La (3% lanthanum carbonate, wt% in feed) for four weeks (La[+] rats), whereas the other half received a placebo (La[-] rats).Results. At the end of this tinge period, creatinine clearance was 1.51 +/- 0.1.5 (mean +/- SEM) and 1.45 +/- 0.11 mL/min in La[-] control and La[+] control rats, and declined to 0.22 +/- 0.03 and 0.31 +/- 0.03 mL/min in La[+]-adenine-CRF and La[+]-Nx-CRF rats, respectively. Urinary La excretion was 0.025 +/- 0.010 mug/24 hr in La[-] control rats. It increased to 4.9 +/- 1.2, 17 +/- 3.8, and 77 +/- 18 mug/24 hr in La[+] control, La[+]-adenine-CRF, and La[+]-Nx-CRF rats, respectively. However, only the last value was significantly different from control value. Tissue La concentration was increased in La[+] control rats compared with La[-] control rats. More importantly, tissue La concentration was strikingly higher in La[+]-CRF rats than in La[+] control rats. Thus, liver La (ng/g dry wt) was 1173 +/- 148 in La[+]-adenine-CRF and 1742 158 in La[+]-Nx-CRF rats, respectively, compared with 385 +/- 29 in La[+] control rats (P < 0.001), and 7.0 +/- 1.4 in La[-] control rats; similarly, bone La was 230 +/- 14 and 288 26 compared with 81 8, respectively (P < 0.001), versus 27 4 in La[-] control rats. Comparable differences were observed in the kidney, skeletal muscle, myocardium, lung, and brain, although to different extents in La[+]-adenine-CRF compared with La[+]-Nx-CRF rats. Finally, liver and kidney weight was significantly reduced in La[+]-adenine-CRF rats compared with La[-]-adenine-CRF rats.Conclusion. The oral administration of lanthanum carbonate to normal rats leads to a more than 10-fold increase of tissue La content in at least some organs, including the liver, lung, and kidney. This increase is further enhanced by the uremic state, per se. Plasma levels are a poor indicator of tissue burden. Given the dramatic tissue levels obtained with this rare earth metal given by the oral route, particularly in liver for absolute values, it is probable that the stimulation by CRF is at least partially explained by an increase in intestinal La absorption. The absorptive pathways involved in intestinal La absorption require further study, including possibly enhancing conditions.

1. Mefloquine is a chiral neurotoxic antimalarial agent showing stereoselective brain uptake in humans and rats. It is a substrate and an inhibitor of the efflux protein P-glycoprotein. 2. We investigated the stereoselective uptake and efflux of mefloquine in mice, and the consequences of the combination with an efflux protein inhibitor, elacridar (GF120918) on its brain transport. 3. Racemic mefloquine (25 mg kg(-1)) was administered intraperitoneally with or without elacridar (10 mg kg(-1)). Six to seven mice were killed at each of 11 time-points between 30 min and 168 h after administration. Blood and brain concentrations of mefloquine enantiomers were determined using liquid chromatography. 4. A three-compartment model with zero-order absorption from the injection site was found to best represent the pharmacokinetics of both enantiomers in blood and brain. (-)Mefloquine had a lower blood and brain apparent volume of distribution and a lower efflux clearance from the brain, resulting in a larger brain/blood ratio compared to (+)mefloquine. Elacridar did not modify blood concentrations or the elimination rate from blood for either enantiomers. However, cerebral AUC(inf) of both enantiomers were increased, with a stronger effect on (+)mefloquine. The efflux clearance from the brain decreased for both enantiomers, with a larger decrease for (+)mefloquine. 5. After administration of racemic mefloquine in mice, blood and brain pharmacokinetics are stereoselective, (+)mefloquine being excreted from brain more rapidly than its antipode, showing that mefloquine is a substrate of efflux proteins and that mefloquine enantiomers undergo efflux in a stereoselective manner. Moreover, pretreatment with elacridar reduced the brain efflux clearances with a more pronounced effect on (+)mefloquine.

Poly(isobutylcyanoacrylate) nanocapsules have been shown to decrease the blood glucose level after oral administration to streptozotocin-induced diabetic fasted rats after 2 days [Diabetes 37 (1988) 246]. Yet, the absorption of insulin in the blood of rats has not been characterised. The aim of this work was to evaluate the biological activity of insulin given orally as nanocapsules. Humalog®-loaded nanocapsules (50 IU/kg) were administered by gavage to streptozotocin-induced diabetic rats. Thirty minutes to 1 h after oral administration, significant levels of human insulin were detected in rat plasma. However, the concentrations were very heterogenous from one rat to another and no decrease of glycemia could be observed. In addition, parenteral injection of insulin in solution showed that high levels of the protein are necessary to decrease blood glucose concentration in diabetic rats. These concentrations were not reached after oral administration. The same dose of insulin decreased glycemia by 50% in normal rats and by only 25% in diabetics. This suggested that an insulino-resistance was developed by streptozotocin-induced diabetic rats.

Inhibitors of P-glycoprotein (P-gp) (verapamil) or cytochrome P-450 (ketoconazole) may reduce IL2 production and T lymphocyte proliferation in vitro. We have examined the effects of chronic oral administration of these drugs and of the cytochrome P450 inductor, carbamazepine, on the hematological and immunological parameters of mice. We found no changes after giving the mice 0.12 mg verapamil, 0.85 mg ketoconazole, or 0.514 mg carbamazepine per mouse for 4 weeks (5 days/week). But giving the drugs for an additional 7 weeks at 0.6 mg (verapamil), 4.25 mg (ketoconazole) or 2.57 mg/mouse (carbamazepine), resulted in significant decreases in monocytes in the verapamil treated group (-51%) and in CD4+ cells in the carbamazepine group (-35%). Chronic oral administration of these drugs reduced the lymphocyte counts of mice by 10-18% and their NK counts by 10-16%. These changes could be due to changes in P-gp function in the transport of IL2, with decreases caused by verapamil and ketoconazole.

BACKGROUND:In chronic renal failure, the renal excretion of certain drugs is dramatically reduced. To determine whether other routes of drug elimination, such as secretion through the intestinal barrier by intestinal P-glycoprotein can be altered, we compared P-glycoprotein activity, P-glycoprotein protein content, and P-glycoprotein mRNA levels in intestine of control and chronic renal failure rats.METHODS:Chronic renal failure was surgically induced in rats by partial (7/8) nephrectomy. After 5 weeks, intestinal transport of rhodamine 123, a P-glycoprotein substrate, was carried out using an in vitro model of everted gut sacs. P-glycoprotein protein content was quantified by enzyme-linked immunosorbent assay and P-glycoprotein mRNA expression was evaluated by semi-quantitative reverse transcriptase polymerase chain reaction.RESULTS:A decrease of intestinal rhodamine 123 transport was observed in chronic renal failure rats, pointing to an inhibition of P-glycoprotein activity. Transport was inhibited in both sham-operated rats and rats with chronic renal failure by verapamil and cyclosporin A, but relative inhibition vs baseline was less marked in chronic renal failure than in sham-operated rats. In contrast, no significant differences in levels of P-glycoprotein protein or mRNA were observed between the two groups.CONCLUSIONS:Intestinal secretion of rhodamine 123 is mainly mediated by P-glycoprotein. It was reduced in rats with chronic renal failure, reflecting reduced intestinal drug elimination via a decrease in P-glycoprotein transport activity rather than via protein underexpression.

The present study was performed to determine the respective involvement of the cellular and paracellular routes in ileal Ca2+ transport. Two groups of rats were either fed a normal Ca2+ diet (1.0%) or a Ca2+-deficient diet (0.02%) for 14 days. Ileal Ca2+ absorption was determined using both an in situ method of continuous luminal perfusion and an in vitro method (Ussing chamber model). The low-Ca2+ diet stimulated net Ca2+ flux in the ileum twofold, associated with a twofold increase of the mucosal-to-serosal Ca2+ flux in both models. This effect was observed in the absence of concomitant changes in Na+ or water flux in the in situ model or mannitol flux in the in vitro model, excluding the participation of the paracellular pathway in Ca2+ transport. Thus only cellular Ca2+ flux was stimulated. These data suggest that the ileum plays a major role in the adaptation to low dietary Ca2+. Whereas under physiological conditions with usual Ca2+ intakes the transcellular pathway of Ca2+ transport is negligible, it becomes of major importance in the case of Ca2+ deficiency, at least under the present conditions of severe Ca2+ deprivation.

OBJECTIVES:The aim of this study was to study the effect of sorbitol on sodium, water and calcium fluxes in rat ileum in situ perfused loop.METHODS:Net water, sodium and calcium fluxes, and one-way calcium fluxes were measured in situ in a perfused rat ileal loop in the presence of varying concentrations of sorbital.RESULTS:High concentrations of sorbitol in perfused ileal solution induced a decrease of sodium and water fluxes and a concomitant increase of lumen to mucosa calcium flux associated with an increase of net calcium flux, using a solution containing either 8.0 or 1.25 mM calcium. These effects were independent of absolute initial values of water and sodium fluxes. They were observed in the presence of 25 mM glucose, 10 mM theophyllin or after treatment of rats with dexamethasone.CONCLUSION:These effects of sorbitol on calcium flux are not compatible with a stimulation of paracellular pathway. By contrast, they can be explained by a stimulation of transcellular calcium pathway in ileum associated with the hyperpolarisation of the cells induced by the decrease of luminal sodium concentration necessary in the presence of sorbitol to maintain unchanged osmolarity of perfusate.

Objectives. - The aim of this study was to study the effect of sorbitol on sodium, water and calcium fluxes in rat ileum in situ perfused loop.Methods. - Net water; sodium and calcium fluxes, and one-way calcium fluxes were measured in situ in a perfused rat ileal loop in the presence of varying concentrations of sorbital.Results. - High concentrations of sorbitol in perfused ileal solution induced a decrease of sodium and water fluxes and a concomitant increase of lumen to mucosa calcium flux associated with an increase of net calcium flux, using a solution containing either 8.0 or 1.25 mM calcium. These effects were independent of absolute initial values of water and sodium fluxes. They were observed in the presence of 25 mM glucose, 10 mM theophyllin or after treatment of rats with dexamethasone.Conclusion. - These effects of sorbitol on calcium flux are not compatible with a stimulation of paracellular pathway. By contrast, they can be explained by a stimulation of transcellular calcium pathway in ileum associated with the hyperpolarisation of the cells induced by the decrease of luminal sodium concentration necessary in the presence of sorbitol to maintain unchanged osmolarity of perfusate.

Blood was obtained by heart puncture from 19-day-old Black Sex link chicken embryos and from Black Sex link chickens at 1.5, 6, or 24 h post-hatching. Plasma testosterone was determined by gas chromatography-mass spectrometry associated with stable isotope dilution. At 19 days the plasma of male and female chick embryos contains measurable amounts of testosterone and levels do not differ between sexes. After hatching plasma testosterone gradually declines from pre-hatch concentrations in males and females, but in all the post-hatch ages studied, plasma testosterone was significantly higher in male than in female chicks. These results indicate that in male chickens, contrary to mammals at birth, there is no surge in plasma testosterone at hatching.

A technique for the extraction, purification and concentration of folates, followed by high performance liquid chromatography assay with fluorometric detection of the three principal derivatives (tetrahydrofolic, 5-methyl-tetrahydrofolic and formyl-tetrahydrofolic acids) has been applied to the determination of tissue folates in rats. The levels found are compared to those of the microbiological assay using Lactobacillus casei. When rats were fed a diet containing 1 mg of folic acid per kg of food, levels in the intestinal mucosae, liver, whole blood and brain were 0.59, 14.87, 0.28 and 0.83 nmol/g of tissue. An exogenous supply of 200 mg of folic acid/kg of food significantly increased folate levels in all tissues studied, except for the brain: 1.51, 28.93, 0.52 and 0.99 nmol/g, respectively in the above four tissues. The separation of the various derivatives and a variable supply of folic acid have enabled the conversions of these metabolites to be studied.

La diphénylhydantoïne (DPH), anticonvulsivant classique utilisé en clinique, est connue pour agir secondairement sur le métabolisme de certaines vitamines et sur différents mécanismes endocriniens, par l'inhibition possible de la libération d'hormones telles que l'ADH, l'insuline, l'ACTH ou la calcitonine (Gharib et Munoz, 1974 ;Pento et al., 1973).Les travaux concernant les effets de la DPH sur le métabolisme de l'acide ascorbique sont peu nombreux.Nous en avons repris l'étude au niveau du foie et des testicules chez le Rat, avant et après le sevrage.La technique colorimétrique choisie utilise la ferrozine comme chélateur du fer réduit par l'acide ascorbique (McGown et al., 1982).