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- Title
Inhibition by (−)-Cicletanine of the Vascular Reactivity to Angiotensin II and Vasopressin in Isolated Rat Vessels.
- Authors
Vargas, Félix; Alvarez-Guerra, Miriam; Droy-Lefaix, Marie-Thérèse; Garay, Ricardo P
- Abstract
In pithed rats, the levorotatory (−)-enantiomer of cicletanine reduces the pressor responses to angiotensin II (AII) and also, to a lesser extent, those to arginine-vasopressin (AVP). Here we have attempted to characterize further these inhibitory effects by studies of isolated perfused rat kidney and mesenteric vascular beds. In the isolated rat kidney, (−)-cicletanine behaves as a noncompetitive antagonist of AII- and AVP-receptor stimulation, with Ki values of 9.6 and 208 μmol/L respectively. In the isolated mesenteric vascular bed, (−)-cicletanine antagonized both AII dependent contractions with an inhibitory concentration (IC50) of 54.0 ± 20.5 μmol/L (n = 6), and AVP dependent contractions with an IC50 of 31.6 ± 5.0 μmol/L (n = 8). In conclusion, (−)-cicletanine antagonizes AII more effectively in rat kidney than in mesenteric vascular beds. Moreover, in rat kidney vascular beds (−)-cicletanine is more potent in blocking the pressor responses to AII than in blocking those to AVP. A selective blockade of AII induced contractions in kidney vascular beds can be one factor explaining both the greater antagonistic potency of (−)-cicletanine against AII compared with AVP in pithed rats, and the renal protective properties of cicletanine in both hypertensive and aged rats.Am J Hypertens (1998) 11, 579-584; doi: S0895-7061(97)00407-X
- Publication
American Journal of Hypertension, 1998, Vol 11, Issue 5, p579
- ISSN
0895-7061
- Publication type
Article
- DOI
10.1016/S0895-7061(97)00407-X