AJP - Heart and Circulatory Physiology, Vol 251, Issue 5 915-H919, Copyright © 1986 by American Physiological Society
Collagen metabolism during right ventricular hypertrophy following induced lung injury
J. E. Turner, M. H. Oliver, D. Guerreiro and G. J. Laurent
Collagen synthesis and degradation rates were estimated in ventricles of
normal rabbits and in those with right ventricular hypertrophy resulting
from bleomycin-induced lung injury. Synthesis rates were estimated from the
radioactivity in tissue [14C]hydroxyproline following a single intravenous
injection of [14C]proline with a "flooding" dose of unlabeled proline
(Biochem. J. 206: 535-544, 1982). The rate in the left ventricle was 5.8
+/- 1.0 compared with 2.9 +/- 0.4%/day in the right (P less than 0.02).
Degradation rates, based on [14C]hydroxyproline levels in the tissue-free
pool, indicated that in both normal ventricles about one-third of newly
produced collagen was degraded rapidly following its synthesis. Six days
after bleomycin, right ventricular collagen content fell by 35%, associated
with a marked increase in tissue-free hydroxyproline levels. After 14 days
the right ventricular weight and collagen content had increased by 49.4 +/-
3.7% (P less than 0.001) and 31.7 +/- 4.4% (P less than 0.05),
respectively, and collagen synthesis rates increased to 9.7 +/- 1.8%/day (P
less than 0.001). It is concluded that collagen is synthesized and degraded
quite rapidly in normal heart tissue but that fractional rates differ
between ventricles. The evidence also suggests that increased collagen
synthesis and breakdown of mature collagen occurs as the connective tissue
matrix is remodeled during adaptive cardiac growth.
