SARCOPLASMIC-RETICULUM CA2- EFFECTS OF PERINDOPRIL( PUMPS IN HEART AND DIAPHRAGM OF CARDIOMYOPATHIC HAMSTER )

The polymyopathy of the Syrian hamster is associated with alterations of cellular calcium regulation and contractile performance of cardiac and skeletal muscles and, in particular, the diaphragm. Angiotensin-co nverting enzyme (ACE) inhibitors have been shown to preserve contracti le performance. Therefore we analyzed the expression of the genes codi ng for the sarco(endo)plasmic reticulum Ca2+-adenosinetriphosphatase ( SERCA) in heart and diaphragm of the cardiomyopathic Syrian hamster (C SH) from the dilated strain Bio 53-58, and we tested the influence of ACE inhibition on accumulation of the different SERCA mRNAs. In the di aphragm of healthy hamsters, two SERCA mRNA isoforms were present: SER CA 1 and SERCA 2. At 6 mo of age, the myopathic process resulted in de creased levels of SERCA 1, whereas the level of SERCA 2 was unchanged. The ACE inhibitor perindopril (1 mg . kg(-1) . day(-1)), administered by force feeding from 1 to 6 mo of age, had no effect on the SERCA 1 mRNA level. In heart, the myopathy was associated with a depressed lev el of SERCA 2 mRNA in 9- but not in B-mo-old animals. Perindopril trea tment from 6 to 9 mo reversed cardiac hypertrophy and the relative dec rease in SERCA 2 mRNA level. Preventive treatment with perindopril fro m 1 to 9 mo tended to prevent (not significantly) the development of c ardiac hypertrophy and reduction in SERCA gene expression. In conclusi on, the myopathic process affects SERCA gene expression in the diaphra gm and subsequently in the heart. Perindopril treatment can prevent SE RCA mRNA loss in heart but not in diaphragm.