AJP - Heart and Circulatory Physiology, Vol 259, Issue 5 1595-H1600, Copyright © 1990 by American Physiological Society
Influence of atrial natriuretic factor on intravascular volume displacement in pigs
D. L. Rutlen, G. Christensen, K. G. Helgesen and A. Ilebekk
University of Oslo, Institute for Experimental Medical Research, Ullevaal Hospital, Norway.
The present study was undertaken to quantitate the influences of
transcapillary fluid loss, urine output, and the capacity vessels on volume
displacement toward and away from the right heart during atrial natriuretic
factor (ANF) administration. In eight anesthetized pigs undergoing carotid
denervation, cervical vagotomy, and splenectomy, blood was drained from the
venae cavae to an extracorporeal reservoir and returned to the right atrium
at a constant rate so that volume displacement toward and away from the
heart could be recorded as change in reservoir volume. Human ANF-(99-126)
(0.1 micrograms.kg-1.min-1) for 15 min was associated with a decrease in
reservoir volume of 2.7 +/- 0.4 ml/kg (P less than 0.05), which resulted
from a decrease in total blood volume of 8.6 +/- 1.0 ml/kg (P less than
0.05) and a displacement from the capacitance vasculature of 5.9 +/- 1.3
ml/kg (P less than 0.05). Since urine output increased only slightly,
virtually all of the total blood volume decrement was due to a displacement
of fluid into the extravascular space. Thus ANF acts to displace volume
away from the right heart. The displacement is due almost entirely to an
increase in transcapillary fluid loss; however, volume displacement from
the capacity vessels to the right heart partially counteracts this
transcapillary influence.
