Running performance and cardiovascular capacity are not impaired in
creatine depleted rats.
Adams, Gregory R., Paul W. Bodell, and Kenneth M. Baldwin.
Department of Physiology and Biophysics, University of California,
Irvine, CA 92717
APStracts 2:0190A, 1995.
Several published reports have indicated that derangement of the
phosphocreatine (PCr) / creatine (Cr) energy buffering system via Cr
analogue feeding results in cardio myopathy when cardiac performance
is assessed in vitro. The present study was designed to examine
indices of cardiac performance in rats which have been chronically Cr
depleted. Adult (1804 g) rats were assigned to a normal diet (ND) (
n=8) or a Cr depletion diet (CD) group (n=10). Following 611 days of
ad libitium feeding, measurements of steady state exercise oxygen
consumption (VO2) were made. Hemodynamic indices were then assessed
during incremental running to peak sustained levels. Rats were then
euthanized and the left ventricle (LV) excised. In the CD group Cr
was depleted 82% and V1 isomyosin decreased while V2 increased. VO2
during steady state running was not different in CD rats. The
respiratory exchange ratios (RER) of CD rats reflected a bias toward
fat utilization during the latter stages of prolonged exercise. The
exercise heart rates and peak systolic blood pressures of CD rats
were slightly lower than those of NDs. Both - and + dP/dt were
significantly reduced at all running speeds in the CD rats. CD rats
were capable of exercise performance equal to that of the ND animals.
The hemodynamic and metabolic data suggest that the adap tations seen
in the CD animals may be similar to those reported following
endurance training. These results indicate that chronic creatine
depletion does not impair either the circulatory or exercise capacity
of rodents.
Received 17 January 1995; accepted in final form 27 April 1995.
APS Manuscript Number A53-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 9 May 1995.