Cardiac force and high-energy phosphates under metabolic inhibition
in four ectothermic vertebrates..
Hartmund, T., and H. Gesser.
Institute of Biological Sciences, University of Aarhus, DK-8000
[angstrom]arhus C, Denmark, FAX:(45)86194186 Tel:(45)89422588
APStracts 3:0129R, 1996.
Isometric twitch tension of ventricular preparations stimulated at 0.2
Hz fell over 30 min of anoxia by a fraction decreasing in the order
rainbow trout, cod, eel, and freshwater turtle. Drops in the
estimated cytoplasmic energy state were related to larger tension
losses for trout than for the other species, possibly due to larger
changes in free phosphate. Anoxic energy degradation was slower for
turtle than for the other species. Anoxia combined with glycolytic
inhibition (1 mmol.l-1 iodoacetate) enhanced the decrease in twitch
tension for a drop in energy state and enlarged the increase in
ADP/ATP relative to that in creatine/phosphocreatine to an extent
inversely related to the creatine kinase activity. Furthermore, it
increased resting tension to an extent possibly related to myosin
-ATPase activity and lowered the content of phosphorylated adenylates
in trout and turtle myocardium. The results indicate that species
-differences in performance of the metabolically challenged myocardium
depend on energy degrading processes e.g. myosin-ATPase activity,
phosphate release, creatine kinase activity, and efflux/degradation
of ADP and amp; and that glycolysis offers protection due to its
cytoplasmic localisation
Received 26 October 1995; accepted in final form 27 March 1996.
APS Manuscript Number R812-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96