AJP - Endocrinology and Metabolism, Vol 267, Issue 3 E447-E453, Copyright © 1994 by American Physiological Society
Effects of substance P on adrenal responses to acetylcholine in conscious calves
A. V. Edwards and C. T. Jones
Physiological Laboratory, University of Cambridge, United Kingdom.
The effect of intra-aortic infusions of substance P (SP; 10 or 20
pmol.min-1.kg-1) on adrenal responses to acetylcholine (4.5 nmol.min-1.kg-1
ia) have been investigated in functionally hypophysectomized calves given
exogenous adrenocorticotropic hormone (0.7 pmol.min-1.kg-1). At the lower
dose, SP had no effect on cortisol output. In contrast, SP inhibited the
output of both catecholamines and enkephalins in response to acetylcholine,
without affecting the output of corticotropin-releasing factor (CRF).
Increasing the dose of SP to 20 pmol.min-1.kg-1 ia significantly reduced
the outputs of both cortisol and CRF (P < 0.025 and 0.01 respectively).
It is concluded that SP is capable of modulating both adrenal cortical and
medullary responses to acetylcholine and that the latter are more sensitive
to this influence than the former.
