Further cholinergic aspects of carotid body chemotransduction of
hypoxia in the cat.
Fitzgerald, Robert S., Machiko Shirahata, Tohru Ide.
Departments of Environmental Health Sciences, Physiology, Medicine,
Anesthesiology/Critical Care Medicine, The Johns Hopkins Medical
Institutions, Baltimore, Maryland 21205
APStracts 3:0544A, 1996.
From the 1930's into the 1970's the role of acetylcholine (ACh) in the
carotid body's chemotransduction of hypoxia was debated. Since the
late 1970's the issue has been pursued only intermittently or not at
all. The purpose of this study was to test again with a new
preparation the hypothesis that ACh is an excitatory neurotransmitter
in the cat carotid body's chemotransduction of hypoxia. We tested the
effect of the specific nicotinic blocker, mecamylamine, and the
muscarinic blocker of all five muscarinic receptors, atropine. We
further tested the effects of M1 and M2 muscarinic receptor blockers.
The carotid body region was selectively perfused with hypoxic Krebs
Ringer bicarbonate solutions (KRB) which were blocker-free or
contained varying doses of the blockers. Both mecamylamine and
atropine reduced the response to hypoxic KRB in a dose-related
manner. The M2 muscarinic receptor blockers, gallamine and AFDX 116,
increased the response to hypoxic KRB, while the M1 muscarinic
receptor blocker, pirenzepine, reduced the response to hypoxic KRB.
These data are consistent with an excitatory role for ACh in the
carotid body chemotransduction of hypoxia in the cat.
Received 21 August 1995; accepted in final form 27 November 1996.
APS Manuscript Number A913-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996