Exercise- and hypertension-induced collagen changes are related to left ventricular function in rat hearts

Maria Lonnett Burgess, James Buggy, Robert L. Price, Francis L. Abel, Louis Terracio, Allen M. Samarel, Thomas K. Borg

Research output: Contribution to journalArticle

Abstract

Chronic hypertension, known to affect the collagen profile of the heart, and exercise result in impaired or improved heart function, respectively. Collagen types I [α1(I)2 and α2(I)] and III [α1(III)3] are the predominant interstitial collagens thought to influence cardiac function, and the ratio of type III to I (collagen 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 vs. 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 maximal rate of fall of the left ventricular pressure (-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 III/I was reduced in Hyp compared with XTr (P < 0.05). Scanning and transmission electron microscopy also supported an accumulation of left ventricular collagen in Hyp compared with XTr. A negative correlation was observed between collagen III/I 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.

Original languageEnglish (US)
Pages (from-to)H151-H159
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume270
Issue number1 39-1
DOIs
StatePublished - 1996

Keywords

  • diastolic function
  • electron microscopy

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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