AJP - Heart and Circulatory Physiology, Vol 249, Issue 2 265-H271, Copyright © 1985 by American Physiological Society
Atrial extract: hemodynamics in Wistar-Kyoto and spontaneously hypertensive rats
B. L. Pegram, M. B. Kardon, N. C. Trippodo, F. E. Cole and A. A. MacPhee
Partially purified low (LMW) and high-(HMW) molecular-weight atrial
natriuretic extracts were administered intravenously (540 micrograms
protein/kg) to conscious Wistar-Kyoto (WKY) and spontaneously hypertensive
(SHR) rats. Both LMW and HMW atrial natriuretic extracts produced an
immediate decrease in mean arterial pressure that reached maximum within 5
min and returned to control levels within 30 min. In both strains, cardiac
output decreased approximately 14% following administration of LMW. Total
peripheral resistance increased only in SHR. Organ blood flow was
significantly decreased to skin, brain, heart, kidneys, and splanchnic
organs of WKY and to skin, muscle, heart, and splanchnic organs of SHR
following administration of LMW. Corresponding increases in organ vascular
resistance index were observed in brain, heart, and splanchnic organs of
WKY and in skin, heart, and splanchnic organs of SHR. To some extent, the
changes in organ blood flow may be a reflection of the decrease in cardiac
output induced by LMW. After administration of HMW, no significant changes
were observed in cardiac output or total peripheral resistance, although
they tended to decrease. Organ vascular resistance was decreased to skin,
muscle, brain, and splanchnic organs of SHR. Little difference was observed
between WKY and SHR responses to atrial natriuretic extracts. These data
indicate that atrial natriuretic extracts have an effect on systemic and
regional hemodynamics in conscious rats that differs markedly from those of
vasodilators such as nitroglycerin or hydralazine.
