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Contribution of the amiloride-sensitive component and the Na+/H+ exchanger to renal responsiveness to
Pablo Vargas1, Rosemary Wangensteen, Isabel Rodríguez-Gómez
1Departamento de Fisiología, Facultad de Medicina, Universidad de Granada, Granada, Spain. fvargas@ugr.es
Aims:
This study analyzed the role of the amiloride-sensitive component and the participation of the Na(+)/H(+) exchanger in renal responsiveness to vasoconstrictors in the isolated perfused rat kidney.
Methods:
The renal responses to vasoconstrictors (angiotensin II, phenylephrine, vasopressin and KCl) were studied under baseline conditions and after the administration of amiloride (10 and 100 μmol/l) or the specific Na(+)/H(+) exchange inhibitor ethylisopropylamiloride (EIPA, 10 μmol/l). The effects of amiloride and EIPA on renal responsiveness to vasoconstrictors were also analyzed in endothelium-denuded preparations.
Results:
Amiloride reduced renal responsiveness to all vasoconstrictors in a dose-related manner, whereas EIPA did not affect the renal pressor response to KCl. The inhibitory effects of amiloride and EIPA on renal responsiveness to vasoconstrictors persisted after endothelium removal.
Conclusion:
These results indicate that the amiloride-sensitive component and the Na(+)/H(+) exchanger play an important role in responsiveness to the main endogenous vasoconstrictors in the renal vasculature. These results also suggest that amiloride might be useful as an inhibitor of renal vasoconstriction, even in diseases with endothelial dysfunction.
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