Drugs online research references
Eur J Pharmacol. 1990 Jun 8;181(3):225-34.
Effect of an angiotensin-converting enzyme inhibitor on blood pressure and erythropoiesis in rats.
Gould AB, Goodman SA.
Department of Medicine, Hahnemann University, Philadelphia, PA 19102.
Positive correlation between systolic blood pressure and plasma renin substrate was demonstrated in Wistar-Kyoto rats when plasma renin substrate was reduced to within a range of 18 and 88% of control values with varying amounts of ramipril. When ramipril was given in amounts that had a maximum effect on systolic blood pressure, marked changes in erythropoietin, reticulocyte count and hematocrit % were observed. Consistent blood pressure-lowering effect was evident for several weeks after ramipril withdrawal. Furthermore, blood pressure obtained 3 days after the rats were taken off ramipril correlated positively with the hematocrit % measured while the rats were still on ramipril (r = 0.83; P less than 0.001). Mean blood volume of 17 rats receiving ramipril was similar to that of the 10 control rats. Plasma and renal renin substrate were highly and positively correlated (r = 0.86; P less than 0.001). Inasmuch as plasma renin substrate is rate-limiting for angiotensin I, it may reflect intrarenal AII and prove to be a useful clinical assessment of converting enzyme inhibition. The increased levels of renin, renin substrate and packed cell volume seen in rats fed Purina basal diet (10% fat) as compared with rats fed Purina lab chow (4.5% fat), support the working hypothesis that intrarenal angiotensin II controls both blood pressure and erythropoiesis.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2143478&dopt=Abstract
Exp Nephrol. 1995 Jul-Aug;3(4):240-8.
Glomerular mRNA expression of angiotensinase A after renal ablation.
Wolf G, Thaiss F, Mueller E, Disser M, Pooth R, Zahner G, Stahl RA.
Department of Medicine, University of Hamburg, Germany.
The local concentration of angiotensin II (ANG II) in the renal microenvironment is not only controlled by the generation of this peptide but also by its enzymatic degradation. Angiotensinase A (ATA; aminopeptidase A, A.C.3.4.11.7) is a major exopeptidase of the glomerulus involvement in the metabolism of ANG II. We studied the glomerular mRNA levels of ATA in a remnant kidney model 1-12 weeks after 1 1/3 nephrectomy. Functional parameters (systolic blood pressure and albuminuria) demonstrated the progression of renal disease in this model. Glomerular ATA enzyme activity significantly increased 1-5 weeks after nephrectomy and returned to control levels 12 weeks after ablation. In general, changes in steady-state mRNA expression for ATA were rather small. mRNA expression for ATA in isolated glomeruli as evaluated by northern blots was slightly increased 1 and 3 weeks after 1 1/3 nephrectomy but was suppressed 5 and 12 weeks after renal ablation compared to age-matched 2-kidney controls. Treatment of animals with the ACE inhibitor ramipril for 5 and 12 weeks partly inhibited the decrease in ATA transcripts after 1 1/3 nephrectomy and stimulated expression in 2-kidney controls whereas the ACE inhibitor decreased glomerular ATA enzyme activity in nephrectomized rats at 5 weeks. Isolated glomeruli from normal controls superfused with 10(-6) M ANG II for 60 min demonstrated no change in ATA transcripts. Our results show that ATA steady-state mRNA levels are slightly elevated early (1-3 weeks) after renal ablation, and are subsequently suppressed (5-12 weeks). ATA enzyme activity is also increased early and returned (12 weeks) to levels measured in age-matched 2-kidney controls.(ABSTRACT TRUNCATED AT 250 WORDS)
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8590037&dopt=Abstract
Br J Pharmacol. 1997 Aug;121(7):1475-81.
ACE inhibitor potentiation of bradykinin-induced venoconstriction.
Hecker M, Blaukat A, Bara AT, Muller-Esterl W, Busse R.
Institute of Physiological Chemistry and Pathological Biochemistry, University of Mainz, Germany.
1. Angiotensin-converting enzyme (ACE) inhibitors exert their cardiovascular effects not only by preventing the formation of angiotensin II (AII), but also by promoting the accumulation of bradykinin in or at the vessel wall. In addition, certain ACE inhibitors have been shown to augment the vasodilator response to bradykinin, presumably by an interaction at the level of the B2 receptor. We have investigated whether this is a specific effect of the ACE inhibitor class of compounds in isolated endothelium-denuded segments of the rabbit jugular vein where bradykinin elicits a constrictor response which is exclusively mediated by activation of the B2 receptor. 2. Moexiprilat and ramiprilat (< or = 3 nM) enhanced the constrictor response to bradykinin three to four fold. Captopril and enalaprilat were less active by approximately one and quinaprilat by two orders of magnitude. Moexiprilat and ramiprilat, on the other hand, had no effect on the constrictor response to AII or the dilator response to acetylcholine. 3. The bradykinin-potentiating effect of the ACE inhibitors was not mimicked by inhibitors of amino-, carboxy-, metallo- or serine peptidases or the synthetic ACE substrate, hippuryl-L-histidyl-L-leucine, at a concentration which almost abolished the residual ACE activity in the vessel wall. In contrast, angiotensin-(1-7) (10 microM), an angiotensin I metabolite, significantly enhanced the constrictor response to bradykinin. 4. Ramiprilat did not alter the binding of [3H]-bradykinin to a membrane fraction prepared from endothelium-denuded rabbit jugular veins or to cultured fibroblasts, and there was no ACE inhibitor-sensitive, bradykinin-induced cleavage of the B2 receptor in cultured endothelial cells. 5. These findings demonstrate that ACE inhibitors selectively potentiate the B2 receptor-mediated vascular effects of bradykinin. Their relative efficacy appears to be independent of their ACE-inhibiting properties and might be related to differences in molecule structure. Moreover, the potentiation of the biological activity of bradykinin by this class of compounds does not seem to be mediated by a shift in affinity of the B2 receptor or a prevention of its desensitization, but may involve an increase in the intrinsic activity of unoccupied B2 receptor molecules.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9257930&dopt=Abstract
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