OBJECTIVETo investigate the effects of spironolactone on the concentration of collagen type I, III in the myocardium of spontaneous hypertension rats (SHR).

METHODSTwenty 8-week male SHR were assigned randomly into spironolactone (SHR-SPIRO, n=10) and control groups (SHR-CON, n=10), sex-age matched Wistar Kyoto rats (WKY group, n=7) were also served as controls. The rats of SHR-SPIRO group were given 20 mg/(kg*d) of spironolactone, the rats of SHR-CON and WKY groups were given the same volume of distilled water. After 16 weeks, the concentration of collagen type I was analyzed with Western blot. The areas of collagen type I and III were observed under polarized light microscopy and the ratio of type I/III collagen was calculated through accumulation score.

RESULTSCompared with WKY group,the concentration of collagen type I in SHR-CON group was significantly higher (1.87 ±0.2 Compared with 1.21 ±0.7, P<0.05). After 16 weeks of treatment the concentration of collagen type I (1.42 ±0.05 Compared with 1.87 ±0.2, P<0.05) and I/III ratio in SHR-SPIRO group were significantly reduced (15.64 ±1.34 Compared with 20.8 ±3.04, P<0.05) compared with SHR-CON group; but there were no differences in accumulation area scores of collagen type III among three groups (368.3 ±30.2 Compared with 481.6 ±32.4 Compared with 406.2 ±45.3, P>0.05).

CONCLUSIONThe deposition of collagen type I in myocardium may be involved in myocardial fibrosis of SHR, and spironolactone can decrease the concentration of collagen type I, which may be one of the mechanisms for its therapeutic effects.