Exercise and hypertension-induced collagen changes are related to
left ventricular function in rat hearts.
Burgess, Maria Lonnett, James Buggy, Robert L. Price, Francis L. Abel,
Louis Terracio, Allen M. Samarel and Thomas K. Borg.
Departments of Developmental Biology & Anatomy and Physiology,
School of Medicine, University of South Carolina, Columbia, SC 29208,
Loyola University of Chicago, Stritch School of Medicine, Maywood, IL
60153
APStracts 2:0402H, 1995.
Chronic hypertension, known to affect the collagen profile of the
heart, and exercise result in impaired or improved heart function,
respectively. Collagen types I [[alpha]1(I)2 and [alpha] 2(I)] and
III [[alpha] 1(III)3] are the predominant interstitial collagens
thought to influence cardiac function, and the ratio of type III/I is
thought to be a significant factor in the altered relaxation observed
in hypertrophy. The present study tested the hypothesis that the
myocardial structure and function are different in chronically
exercise-trained verses hypertensive rat hearts. Male rats were
either chronically exercised (XTr) or submitted to experimental
hypertension by coarctation of the abdominal aorta (HYP) for 10 wks.
Heart rate, blood pressure and left ventricular dP/dt were recorded
during isoproterenol stimulation. Results showed that both HYP and
XTr had higher heart weight and left ventricular weight to body
weight ratios (p<0.05). Mean arterial pressure (MAP) was higher
in HYP and lower in XTr (p<0.05), whereas -dP/dt/MAP was
diminished in HYP but enhanced in XTr. Left ventricular collagen was
higher in HYP than XTr whereas collagen type III/I ratio was reduced
in HYP compared to XTr (p<0.05). SEM and TEM also supported an
accumulation of left ventricular collagen in HYP compared to XTr. A
negative correlation was observed between the collagen III/I ratio
and -dP/dt/MAP (r=-0.91; p<0.05). These results suggest an
important relationship between adaptations in left ventricular
collagen and the changes in diastolic function observed in both
chronic hypertension and exercise cardiac stress.
Received 11 October 1994; accepted in final form 10 July 1995.
APS Manuscript Number H903-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.