Differential regulation of renal regional blood flow by endothelin
-1.
Gurbanov, Konstantin, Irith Rubinstein, Aaron Hoffman, Zaid Abassi,
Ori S. Better, and Joseph Winaver.
Department of Physiology and Biophysics and R. Chutick crush
research center, Faculty of Medicine, Technion-Israel Institute of
Technology, Haifa 31096, Israel
APStracts 3:0168F, 1996.
The present study evaluated the effects and mechanisms of action of
endothelin-1 (ET-1) on medullary and cortical blood flow (MBF and CBF
respectively). CBF and MBF were measured simultaneously by laser
-Doppler flowmetry in anesthetized male Wistar rats. Bolus injection
of ET-1 (1.0 nmol/kg, iv) produced a sustained decrease in CBF (_=
-30%) and a transient increase in MBF (_= +35%). The medullary
vasodilation induced by ET-1 was observed with doses lower than that
required to produce cortical vasoconstriction; was completely blocked
by bosentan, a mixed ETA/B receptor antagonist; and was mimicked by
IRL 1620, a specific ETB receptor agonist. In contrast, BQ-123, an
ETA receptor antagonist, failed to inhibit the ET-1-dependent
medullary vasodilation, but effectively blocked the cortical
vasoconstriction induced by the peptide. Finally, inhibition of
nitric oxide (NO) synthase completely abolished, whereas
cylooxygenase inhibition attenuated, the effect of ET-1 on MBF.
Received 28 February 1996; accepted in final form 27 August 1996.
APS Manuscript Number F71-6.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996