Cortisol disposition and production rate in horse during rest and
exercise.
Lassourd, V., V. Gayrard, V. Laroute, M. Alvinerie*, P. Benard, D.
Courtot, P. L. Toutain.
Ecole Nationale V[umlaut]at[umlaut]arinaire de Toulouse,
D[umlaut]apartement de Physiopathologie et Unit[umlaut]a
associ[umlaut]ae INRA de Physiopathologie et Toxicologie
Exp[umlaut]arimentales, 23, chemin des Capelles F-31076 Toulouse
cedex, INRA, Station de Pharmacologie, B.P. 3, 31931 Toulouse cedex,
Unit[umlaut]a associ[umlaut]ae INRA de Toxicologie
M[umlaut]atabolique et Ecotoxicologie, 1, avenue Bourgelat, B.P. 83,
69280 Marcy-l'Etoile
APStracts 2:0336R, 1995.
The influence of a 56 km-endurance exercise on cortisol kinetics and
production rate was evaluated in six horses administered with
[3H]cortisol. Exercise resulted in an immediate two to threefold
increase in plasma cortisol, with values returning very rapidly to
preexercise levels. During exercise, clearance and steady-state
volume of distribution of total cortisol were largely increased : 338
95 ml/kg/h versus 137 34 ml/kg/h for clearance and 359 82 ml/kg
versus 229 18 ml/kg for the volume of distribution whereas the
terminal half-life decreased significantly (0.97 0.16 h versus 1.55
0.33 h). The estimated cortisol production rate was 4.41 1.06 g/kg/h
at rest and 26.75 5.11 g/kg/h during exercise. It is concluded that
exercise triggers a large increase (x 6) in the adrenal secretion
rate which is not accurately reflected by the more limited increase
(x 2-3) in plasma cortisol concentration, the actual measurement of
plasma cortisol clearance being a prerequisite to the assessment of
adrenal gland function during exercise.
Received 17 July 1995; accepted in final form 20 November 1995.
APS Manuscript Number R447-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95