Renal responses to intra-arterial administration of adrenomedullin
in dogs.
Majid, Dewan S. A., Philip J. Kadowitz, David H. Coy, and L. Gabriel
Navar.
Departments of Physiology, Pharmacology & Medicine, Tulane
University School of Medicine, 1430 Tulane Avenue, New Orleans, LA
70112, 504-588-5251
APStracts 2:0133F, 1995.
The present study was undertaken to evaluate the renal responses to
intra-arterial infusion (12.5 pmol_Kg-1_min-1) for 30 min of
adrenomedullin (ADM) in denervated kidneys of anesthetized dogs
(n=8). Total Renal blood flow (RBF) was measured with an
electromagnetic flow-probe and two single-fiber laser-Doppler needle
flow-probes were used to measure relative changes in cortical (CBF)
and medullary blood flow (MBF). ADM administration resulted in
decreases in renal vascular resistance (32.3+/-4.9 to 22.3+/-3.0
mmHg_min-1_min-1_g-1) and increases in RBF (4.5+/-0.5 to 6.0+/-0.6
ml_min-1_g-1), CBF (33+/-1.3%, n=4) and MBF (32+/-5.7%, n=5) without
changes in glomerular filtration rate. There were also substantial
increases in urine flow (11.3+/-1.9 to 28+/-4.8 [mu]l_min-1_g-1), as
well as in sodium excretion (1.8+/-0.2 to 4.2+/-0.6 [mu]l_min-1_g-1).
After cessation of ADM infusion, a partial recovery of these
responses were observed within a 30 min period. Responses to ADM were
attenuated during inhibition of nitric oxide (NO) synthesis by nitro
-L-arginine (50 [mu]g_kg-1_min-1). These findings indicate that renal
vasodilator, diuretic and natriuretic responses to ADM may be
mediated by the release of endogenous NO and suggest that ADM could
play a role in regulating water and electrolyte excretion by the
kidney.
Received 3 May 1995; accepted in final form 31 July 1995.
APS Manuscript Number F145-5.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 August 1995.