Deleterious effect of exogenous angiotensin-I on the extent of regional ischaemia and its inhibition by captopril |
| |
Authors: | RUMP, A. F. E. ROSEN, T. J. KORTH, A. KLAUS, W. |
| |
Affiliation: | Institut für Pharmakologie Universität Köln Germany |
| |
Abstract: | The endogenous activity of the local renin-angiotensin system(RAS) and the anti-ischaemic properties of captopril were investigatedin electrically driven rabbit Langendorff hearts (constant pressure:70 cmH2O, Tyrode solution, Ca2+ 1.8 mmol.l1). Cumulativeconcentration-response curves showed no significant difference(P>0.05) between the reduction of the global coronary flow(CF) by exogenous angiotensin-I or angiotensin-II (EC50 = 1010mol.l1). It is concluded that the local RAS in isolatedrabbit hearts is highly sensitive, whereas its endogenous activityis very low due to very low endogenous angiotensin-I content.Myocardial ischaemia (MI) was induced by the occlusion of aleft coronary artery branch and MI was quantified from NADHsurface fluorescence photography. MI was significantly enlarged(+35%) (P <0.05) by exogenous angiotensin-I (6x109mol.l1). The reduction in CF and the increment in MIby angiotensin-I could be completely prevented by adding captoprilat a low concentration (106 mol.l1) to the perfusionbuffer. In the absence of exogenous angiotensin-I, captoprilalone (106 mol.l1) neither significantly enhancedCF (P >0.05), nor diminished MI (P >0.05), supportingthe finding of very low endogenous activity of tile local RASin this model. We, moreover, conclude that at a low concentration(106 mol.l1) captopril does not possess directcardioprotective properties independent of its ACE inhibitingaction. |
| |
Keywords: | NADH fluorescence angiotensin angiotensin-converting enzyme myocardial ischaemia ACE inhibitors captopril cardioprotection |
本文献已被 Oxford 等数据库收录! |
|