Environmental versus functional hypoxia/anoxia in sole (solea
solea): the lactate paradox revisited.
Via, Josef Dalla, Guido Van Den Thillart, Otello Cattani, and Paolo
Cortesi.
Department of Zoology and Limnology, Section of Ecophysiology,
University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck,
Austria, Department of Biology, University of Leiden, Gorlaeus
Laboratoria, POB 9502, NL-2300-RA Leiden, The Netherlands, Department
of Biochemistry, University of Bologna, Via Tolara di Sopra 50, I
-40064 Ozzano Emilia (Bologna), Italy
APStracts 3:0406R, 1996.
The effects of hypoxia (12% and 6% air saturation), anoxia, forced
exercise and the first four hours of recovery after exhaustive
exercise on intermediary metabolism were compared in common sole
(Solea solea). Intermediates of energy metabolism and lactate
production were analyzed in white muscle, liver and blood. The ATP
produced by anaerobic metabolism was calculated for the 4 different
conditions, i.e. for 12% hypoxia, 6% hypoxia, anoxia, and forced
exercise and the rates were 52, 150, 1777, and 6834 [mu]mol.100g-1.h
-1, respectively. The total anaerobic ATP yield was 625, 1799, 3074,
and 3132 [mu]mol ATP.100g-1. While under hypoxia the energy
consumption of the animals appeared to be depressed (i.e. below
standard metabolic rate), the rate under anoxia was at routine
metabolic rate, and under forced exercise at two times active
metabolic rate. The muscle/blood lactate ratio after forced exercise
was comparable to those found previously for other flatfish species,
however, hypoxia exposure resulted in a complete inverse picture with
blood lactate levels up to 20 mM, whereas anoxia resulted in an
intermediate situation. The results challenge the present concept of
lactate "releasers" and "non-releasers"
describing the transfer of lactate from muscle tissue into the blood.
It is concluded that the distinction between lacate
"releasers" and "non-releasers" can no longer be
applied on a species basis but must be related to type and intensity
of the induced stress situation.
Received 14 February 1996; accepted in final form 16 October
1996.
APS Manuscript Number R94-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996