AJP - Heart and Circulatory Physiology, Vol 256, Issue 3 852-H858, Copyright © 1989 by American Physiological Society
Influence of volume expansion on hemodynamic effects of atrial natriuretic factor in rabbits
M. Volpe, A. Cuocolo, F. Vecchione, G. Lembo, S. Pignalosa, M. Condorelli and B. Trimarco
Istituto di Clinica Medica, Facolta di Medicina, Universita di Napoli, Naples, Italy.
We investigated the influence of acute volume expansion on the hemodynamic
and renal responses to the constant infusion of atrial natriuretic factor
(ANF) (alpha-human ANP, 2 micrograms/kg bolus, 0.2 microgram.kg-1.min-1) in
rabbits anesthetized with ketamine and acepromazine. The effects of the
peptide were evaluated in 12 euvolemic rabbits and in 15 rabbits during the
steady-state phase of volume expansion (0.9% NaCl 4.5 ml/min for 60 min).
In the euvolemic animals, ANF caused an increase in natriuresis and a
reduction in blood pressure (BP), which was associated with a decrease in
cardiac output (CO), stroke volume (SV), and no significant changes in
central venous pressure (CVP), peripheral hematocrit (Hct), and heart rate
(HR). When the peptide was infused in the volume-expanded animals, the
effects of ANF on BP and HR were comparable with those observed in the
euvolemic animals. However, in these animals the ANF-induced changes in CO,
SV, CVP, and Hct were significantly greater than those observed in the
euvolemic group. In addition, the percent increases in diuresis and
natriuresis were significantly smaller than those obtained in the euvolemic
animals. In conclusion, volume expansion with saline potentiates the
effects of ANF on systemic hemodynamics and blood volume.
