Influence of sarmesin on the cardiac and vascular actions of angiotensin II |
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| Authors: | Stefan Mihailescu John M. Matsoukas Francis L. Abel Valeriu Nestianu Florin Romanescu Cristina Alecu-Parvu |
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| Affiliation: | (1) Department of Physiology, Faculty of Medicine, 4 Petru Rares Street, RO-1100 Craiova, Romania;(2) Department of Chemistry, University of Patras, 26500 Patras, Greece;(3) Department of Physiology, School of Medicine, University of South Carolina, 29208 Columbia, SC, U.S.A. |
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| Abstract: | Summary The angiotensin II (ANG II) receptor blocker properties of sarmesin and its influence on the homotropic cooperativity of ANG II receptors were studied in two experimental models: isolated rabbit aorta and isolated rabbit atria. The results show that: (i) sarmesin is a specific competitive antagonist of ANG II receptors, with high affinity (pA2=8.93 in the isolated aorta and 8.66 in the isolated atria); and (ii) the slope of the concentration-response curves to ANG II and the Hill coefficient increased in the presence of sarmesin, the latter suggesting an enhancement of the positive homotropic cooperativity of ANG II receptors. These results may be explained overall by the reciprocal negative modulation of receptor affinity between sarmesin and ANG II, due, possibly, to opposite effects on the binding of G-proteins to ANG II receptors. |
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| Keywords: | Homotropic cooperativity Angiotensin II Receptors Isolated rabbit aorta Isolated rabbit atria |
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