AJP - Regulatory, Integrative and Comparative Physiology, Vol 266, Issue 5 1503-R1509, Copyright © 1994 by American Physiological Society
Acute hypocapnia blunts natriuretic and diuretic effects of atrial natriuretic factor in rats
Y. Mimura, A. A. Khraibi, D. M. Heublein and F. G. Knox
Department of Physiology and Biophysics, Mayo Clinic and Foundation, Rochester, Minnesota 55905.
Recent studies suggest that the autonomic nervous system, when activated by
respiratory alkalosis, may attenuate the renal effects of atrial
natriuretic factor (ANF). We evaluated the renal responses to infusion of
ANF during acute exposure to hypocapnia in the presence or absence of the
renal nerves in anesthetized rats. In this study, renal function during
hypocapnia was assessed and was compared with renal function during
normocapnia produced by normal ventilation as well as by hyperventilation.
Rats were divided into three experimental groups (n = 8): 1) a normally
ventilated normocapnic (NV-N) (control) group; 2) a hyperventilated
normocapnic (HV-N) group; and 3) a hyperventilated hypocapnic (HV-H) group.
The innervated (Inn) right kidney served as a control for the contralateral
denervated (DNX) kidney. In Inn and DNX kidneys of HV-H rats, an infusion
of ANF (12 micrograms.kg-1.h-1) produced a smaller increase in urine flow
rate (delta V: 9.8 +/- 3.9 and 1.3 +/- 4.2 microliters/min) and in
fractional Na excretion (delta FENa: 1.35 +/- 0.52 and 0.73 +/- 0.58%)
compared with NV-N rats (delta V: 37.6 +/- 4.9 and 59.9 +/- 9.7
microliters/min; delta FENa: 3.24 +/- 0.37 and 3.88 +/- 0.65%). No
differences were observed in delta V and delta FENa in Inn kidney between
HV-H and HV-N groups; however, the attenuated natriuretic and diuretic
responses to ANF in DNX kidney of HV-H rats were also observed in
comparison with HV-N rats (delta V: 27.4 +/- 4.3 microliters/min; delta
FENa: 2.94 +/- 0.48%). ANF induced natriuresis in DNX kidney to the same
degree in NV-N and HV-N rats.(ABSTRACT TRUNCATED AT 250 WORDS)
