M. Honda et al., BIOCHEMICAL REMODELING OF COLLAGEN IN THE HEART OF SPONTANEOUSLY HYPERTENSIVE RATS - PROMINENT INCREASE IN TYPE-V COLLAGEN, Japanese Circulation Journal, 57(5), 1993, pp. 434-441
To determine how collagen is remodeled in the heart during the develop
ment of cardiac hypertrophy, the collagen concentration and the propor
tions of types I, III, and V collagen were analyzed in the hearts of 1
0-, 20-, 32-, and 40-week-old spontaneously hypertensive (SHR) and Wis
tar-Kyoto (WKY) rats. The collagen concentration was calculated after
the hydroxyproline content was measured and the proportions of types I
, III, and V collagen were determined by non-interrupted SDS-polyacryl
amide gel electrophoresis (SDS-PAGE). There was no significant differe
nce between the collagen concentrations in 10-week-old SHR and WKY. At
20 weeks, the collagen concentration in the hearts of the SHR had-dec
reased significantly (p<0.01) when compared to that in the WKY, at 40
weeks, this concentration in SHR had increased significantly (p<0.05)
when compared to that in the WKY. Type V collagen in WKY increased wit
h age and type I collagen in the 20- and 40-week-old WKY decreased sig
nificantly (p<0.05) when compared to that in the 10-week-old WKY. Howe
ver, the proportion of type I collagen in the 20-week-old WKY did not
differ from that of the 40-week-old WKY. There was no significant diff
erence between the proportions of the various types of collagen in 10-
week-old SHR and those in age- and sex-matched WKY. However, the propo
rtion of type V collagen in the 20- and 40-week-old SHR was significan
tly (p<0.01) higher than that in age- and sex-matched WKY. Moreover, t
he proportion of type I collagen in the 40-week-old SHR was significan
tly (p<0.01) lower than that in age- and sex-matched WKY. The III/I ra
tio of the 40-week-old SHR was significantly higher than that of age-m
atched WKY (p<0.05). These results show qualitatively and quantitative
ly that collagen is remodeled as cardiac hypertrophy develops and that
there is a prominent increase in type V collagen. This suggests that
type V collagen is involved in the pathogenesis of cardiac hypertrophy
in SHR.