Effects of hypoxia on carotid body dopamine content and release in
developing rabbits.
A., Bairam, H. Basson, F. Marchal, J. M. Cottet-Emard, J. M.
Pequignot, J. M. Hascoet, and S. Lahiri.
Laboratoire de Physiologie, Facult[acute]e de M[acute]edecine de
Nancy, Vand_uvre l[grave]es Nancy, CNRS URA 1195, Laboratoire de
Physiologie de l'Environnement, Lyon, INSERM U272, Nancy, France,
Centre de Recherche HSFA, Universit[acute]e Laval, Qu[acute]ebec,
Canada, Department of Physiology, University of Pennsylvania,
Philadelphia, USA
APStracts 2:0391A, 1995.
Hypoxia induces dopamine (DA) release from the carotid body (CB), but
the role of DA during hypoxia in the postnatal maturation of carotid
chemosensory discharge remains controversial. The aim of this study
was to evaluate changes in carotid body DA content and release evoked
by hypoxia at different stages of development in the rabbit. Five
groups of rabbits aged respectively /= 1 year (n = 11) were
studied. CB's were surgically removed and immediatly incubated at 37
C for one hour in a surviving medium equilibrated with 100% O2 or 8%
O2 in N2. The content of DA in the CB ([DA]CB) and the DA released in
the surviving medium ([DA]r) were measured by HPLC. [DA]CB was
significantly larger in adults than in all pup groups in both 100% O2
(mean +/-?SEM: 385.5 +/- 74.1 pmol/CB in adults and 43.6 +/-?6.0
pmol/CB* in pups) and hypoxia (518.1 +/- 99.9 pmol/CB in adults and
24.7 +/- 3.2 pmol/CB* in pups), presumably because of the larger CB
mass. [DA]r was significantly larger in hypoxia than in 100% O2 only
in 25 day olds (respectively 19.8 +/- 4.2 pmol/h and 3.6 +/- 1.1
pmol/h*) and adults (respectively, 183.9 +/- 57.7 pmol/h and 7.9 +/-
1.7 pmol/h*). The average ratio of [DA]r in hypoxia to [DA]r in 100%
O2 ranged from 1.3 to 2.2 in the three younger age groups, and 5.5
and 23.3 in respectively 25 day olds and adults. It is concluded that
the release of DA evoked by hypoxia is weak at birth and develops
during the first weeks of life in the rabbit.
Received 12 April 1994; accepted in final form 17 August 1995.
APS Manuscript Number A333-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.