[Signal transductional mechanism of calpain involved in the regulation of rat hypertrophy myocardium mediated by overloaded pressure].

OBJECTIVE

To investigate the signal regulation of angiotensin I receptor on calpain system in rat hypertrophy myocardium mediated by overloaded pressure.

METHODS

The rat model of hypertrophy myocardium mediated by overloaded pressure was established by abdominal aorta constriction. Forty male wistar rats were randomly divided into four groups: namely sham-operated group, banding group, valsartan group (banding group and valsartan administration 1 mg/kg x d), and PD123319 group (banding group and PD123319 administration 30 mg/kg x d). Concentrations of Ang II in serum and left ventricular septum were measured by radioimmunoassays. The immunoprecipitation method was used to assay the protein expression of calpain system, the phosphorylation and expression of calcineurin, the protein expression of cain/cabinl in myocardial tissues of left ventricular septum. The message RNA (mRNA) expression of beta-myosin heavy chain (beta-MHC) in myocardial tissue was analyzed using reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The Ang II concentration in serum and left ventricular septum tissue of banding group was higher than that of sham-operated group, valsartan group or PD123319 group (P < 0.01) respectively; the Ang I concentration in serum of valsartan group was lower than that of banding and PD123319 groups (P < 0.05), but higher in left ventricular septum tissues (P < 0.05). The expression of u-calpain protein, phosphorylation of calcineurin, mRNA expression of beta-MHC in left ventricular septum tissue of banding group was higher than that of sham-operation group (P < 0.01), the expression of cain/cabin1 was lower than that of sham-operation group (P < 0.01); the protein expression of u-calpain, phosphorylation of calcineurin and mRNA expression of beta-MHC were lower (P < 0.05), and cain/cabin1 protein expression in valsartan group was higher than that in banding and PD123319 groups (P < 0.05), but there was no expressibly big differences between banding and PD123319 group (P > 0.05).

CONCLUSION

The cain/cabin1, an inhibiting protein factor of calcineurin, degraded by u-calpain with AT1 involves the calcineurin signaling pathway activated and the rat myocardium going to hypertrophy processed under overloaded pressure.