AJP - Regulatory, Integrative and Comparative Physiology, Vol 273, Issue 1 252-R258, Copyright © 1997 by American Physiological Society

ARTICLES

Structural and biochemical analyses of cardiac ventricular enlargement in cold-acclimated striped bass

K. J. Rodnick and B. D. Sidell
Department of Biological Sciences, Idaho State University, Pocatello 83209-8007, USA.

We examined effects of temperature acclimation on ultrastructural characteristics of cardiac myocytes and maximal activities of metabolic enzymes in cardiac tissue of striped bass (Morone saxatilis). Ventricular mass and ventricular mass divided by body weight were significantly increased (29% and 40%, respectively) in animals acclimated to cold (5 degrees C) vs. warm temperatures (25 degrees C). Mean myocyte diameter was increased at cold temperature (3.47 +/- 0.14 vs. 2.98 +/- 0.08 microns), which is sufficient to explain the increase in ventricular mass. Ventricular enlargement did not alter volume densities of mitochondria, myofibrils, protein concentration, or citrate synthase activity. Thus total volume of mitochondria and myofibrils increased proportionately with cardiac mass in cold animals. Activities of hexokinase (34%) and carnitine palmitoyltransferase (42%) increased in cold animals, suggesting positive compensation and increased aerobic capacity for utilization of glucose and fatty acids for energy production. Enlargement of the ventricle and an increased capacity for ATP production in striped bass may help compensate for kinetic constraints at cold temperatures and maintain circulatory support to oxidative axial musculature for swimming activity.

This article has been cited by other articles:

				M. Vornanen, M. Hassinen, H. Koskinen, and A. Krasnov Steady-state effects of temperature acclimation on the transcriptome of the rainbow trout heart Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2005; 289(4): R1177 - R1184. [Abstract] [Full Text] [PDF]