AJP - Regulatory, Integrative and Comparative Physiology, Vol 259, Issue 3 585-R592, Copyright © 1990 by American Physiological Society
Intrarenal atrial natriuretic peptide infusion lowers arterial pressure chronically
D. A. Hildebrandt, H. L. Mizelle, M. W. Brands, C. A. Gaillard, M. J. Smith Jr and J. E. Hall
Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson 39216.
Chronic intravenous infusions of atrial natriuretic peptide (ANP) have been
shown to lower mean arterial pressure (MAP) in both normal and hypertensive
animals. However, the importance of the renal actions of ANP in mediating
this hypotension is unknown. This study was designed to determine whether
physiological or pathophysiological increases in intrarenal ANP levels
influence long-term control of arterial pressure. ANP was infused into the
renal artery of seven conscious, uninephrectomized, chronically
instrumented dogs at 1, 2, and 4 ng.kg-1.min-1 for 7 days at each dose,
followed by a recovery period. Then ANP was infused intravenously following
the same protocol. MAP decreased from 88 +/- 3 to 78 +/- 3 mmHg during
intrarenal infusion of 1 ng.kg-1.min-1 ANP; increasing the ANP infusion
rate did not result in a further reduction in MAP. Systemic arterial plasma
ANP concentration did not change from control (15 +/- 5 pg/ml) during 1 or
2 ng.kg-1.min-1 intrarenal ANP infusion but increased slightly during 4
ng.kg-1.min-1 intrarenal ANP infusion, averaging 53 +/- 11 pg/ml. Renal
arterial plasma ANP concentrations were calculated to increase to
approximately 120 +/- 5, 248 +/- 11, and 484 +/- 22 pg/ml during 1, 2, and
4 ng.kg-1.min-1 intrarenal ANP infusion, respectively. Intravenous ANP
infusion did not alter MAP at 1 ng.kg-1.min-1, but MAP was slightly lower
than control during 2 and 4 ng.kg-1.min-1 ANP infusion and remained below
control during the postinfusion period.(ABSTRACT TRUNCATED AT 250 WORDS)
