AJP - Regulatory, Integrative and Comparative Physiology, Vol 240, Issue 3 166-R174, Copyright © 1981 by American Physiological Society
Prostaglandins, catecholamines, and cardiovascular responses to hemorrhage
G. Feuerstein, D. C. Jimerson and I. J. Kopin
The effects of prostaglandins (PGE2 and 16,16-dimethyl-PGE1) on epinephrine
(E) and norepinephrine (NE) release, in response to a hypotensive stimulus
(bleeding 5 ml/300 g), were studied in relation to blood pressure and heart
rate responses in the rat. PGE2 (10 micrograms/kg-1 . min-1) and
16,16-dimethyl-PGE1 (1 microgram . kg-1 . min-1) accelerated blood pressure
and heart rate recovery rate following acute hemorrhage and increased
plasma E and NE levels. Plasma levels of 3-methoxy-4-hydroxyphenylglycol
(MHPG) and 3,4-dihydroxyphenylglycol (DHPG) were not affected by PG
infusion. In bilaterally nephrectomized rats, PGE2 increased plasma levels
of E, NE, and DHPG but failed to enhance the blood pressure and had only a
mild effect on heart rate recovery following bleeding. In
hexamethonium-treated rats, infusion of PGE2 had a small and transient
effect on blood pressure recovery, but its effect on the heart rate was not
affected; NE and E levels in the plasma of the hexamethonium-treated rats
were still higher in the PGE2-infused rats. These studies indicate that in
the intact rat, administered PGE potentiate the release of E and NE and
facilitate blood pressure and heart rate recovery following acute
hemorrhage. The hemodynamic effects of the PGE appear to be mediated by a
renal factor whereas the effects of PGE on E and NE response to hemorrhage
are independent of the presence of intact kidneys.
