AJP - Heart and Circulatory Physiology, Vol 256, Issue 1 233-H239, Copyright © 1989 by American Physiological Society
Adrenergic receptors of adrenal medullary vasculature
D. A. Jordan, M. J. Breslow, K. L. Kubos and R. J. Traystman
Department of Anesthesiology, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205.
The present study evaluates possible effects of adrenal catecholamines,
released by splanchnic nerve stimulation, on adrenal medullary blood flow
(MQ) and adrenal catecholamine secretion (CS). Twelve
pentobarbital-anesthetized mongrel dogs were subjected to three identical
splanchnic nerve stimulations (5 V, 20 Hz, for 3 min) at 30-min intervals,
and MQ (radiolabeled microsphere technique) and CS (high-performance liquid
chromatography) were measured before and during each nerve stimulation.
Animals were assigned to one of three groups and administered either
saline, pindolol (1 and 4 mg/kg), or prazosin (1 and 4 mg/kg) before the
second and third nerve stimulation, respectively. In the saline control
group, each nerve stimulation resulted in similar increases in MQ and CS.
Pindolol attenuated nerve stimulation-induced increases in MQ and CS by
50%, but had no effect on medullary catecholamine concentration. Prazosin
augmented nerve stimulation-induced MQ, CS, and medullary catecholamine
concentration by 35%. These data suggest that adrenal adrenergic receptors
modulate elicited CS and mediate changes in adrenal medullary vascular
tone.
