AJP - Cell Physiology, Vol 251, Issue 5 737-C747, Copyright © 1986 by American Physiological Society
Lysosomal changes during thyroxine-induced left ventricular hypertrophy in rabbits
M. S. Parmacek, M. L. Decker, M. Lesch, A. M. Samarel and R. S. Decker
By use of a combined morphologic, immunocytochemical, and biochemical
approach, this study demonstrates the changes in the lysosomal vacuolar
apparatus that accompany thyroxine-induced cardiac hypertrophy. During the
1st wk of thyroxine administration, immunocytochemical studies revealed a
decline in cathepsin D within many myocytes, but an increase within
interstitial cells. These events transpired with only a modest rise in
cathepsin D activity. During the 2nd wk, cathepsin D reappeared within most
myocytes and continued to increase within the interstitial population and
was associated with a general rise in lysosomal enzyme activity. These data
demonstrate the importance of employing both immunocytochemical and
biochemical approaches to evaluate the status of the lysosomal vacuolar
apparatus, and suggests that the lysosomal vacuolar apparatus may be
involved in the apparent remodeling that attends rapid cardiac growth,
which may represent one component of the enhanced rates of proteolysis
documented in this model of cardiac hypertrophy.
