AJP - Regulatory, Integrative and Comparative Physiology, Vol 256, Issue 6 1245-R1249, Copyright © 1989 by American Physiological Society
Atrial natriuretic factor induces natriuresis during pacing tachycardia in dogs
G. Christensen, J. F. Bugge, A. Ilebekk and F. Kiil
Institute for Experimental Medical Research, University of Oslo, Ulleal Hospital, Norway.
To examine whether release of atrial natriuretic factor (ANF) can explain
the increase in sodium excretion during supraventricular tachycardia, we
compared the natriuretic responses with right atrial pacing tachycardia and
ANF infusion in six barbiturate-anesthetized dogs. When we raised the dogs'
heart rates from 148 +/- 12 to 263 +/- 12 beats/min for 30 min, plasma
immunoreactive (IR) ANF rose from 42.1 +/- 3.4 to 139.0 +/- 25.6 pg/ml.
Sodium excretion increased from 36.2 +/- 12.8 to 132.4 +/- 40.8 mumol/min
in the exposed denervated kidney. When we infused 12.5 ng.min-1.kg body
wt-1 of ANF at a spontaneous heart rate of 146 +/- 12 beats/min, plasma
IR-ANF rose from 46.0 +/- 5.1 to 121.7 +/- 17.5 pg/ml, which was similar to
that observed during pacing tachycardia. Sodium excretion increased from
40.6 +/- 11.3 to 193.6 +/- 46.0 mumol/min, which was higher than that
observed during pacing tachycardia. Renal blood flow was lower during
pacing tachycardia than during ANF infusion, but glomerular filtration rate
and aortic blood pressure were not significantly different during the two
procedures. Because sodium excretion was 30% lower during pacing
tachycardia, even though plasma IR-ANF was as high as during ANF infusion,
we conclude that ANF induces the acute rise in sodium excretion during
pacing tachycardia but that hemodynamic changes may attenuate the
natriuretic response.
