BACKGROUNDChronic heart failure (CHF) is associated with calcium transients and calcium handling proteins. Angiotensin converting enzyme (ACE) inhibitor has been demonstrated to have beneficial effect on CHF. Yet studies addressed to the relationship between ACE inhibitor and calcium transients in CHF are rare. The aim of this study was to investigate the influence of ACE inhibitor (perindopril) on the contractility and calcium transients and calcium handling proteins in ventricular myocytes from rats with experimental heart failure.

METHODSMale Wistar rats were randomized to heart failure group treated with perindopril [CHF-T, 3 mg.kg(-1).d(-1)], heart failure group without treatment (CHF-C) and sham-operated group (PS). Heart failure was induced by abdominal aortic constriction. All groups were further followed up for 12 weeks. Left ventricular myocytes were then isolated. Single cell shortening fraction and [Ca(2+)]i were simultaneously measured by laser scanning confocal microscope under the field stimulation (1.0 Hz). Reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot were performed to evaluate the changes of mRNA and protein of Na(+)-Ca(2+) exchanger (NCX1), sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2) and phospholamban (PLB).

RESULTSThe fraction of cell shortening (FS%) and [Ca(2+)]imax (nmol/L) were significantly reduced in group CHF-C compared with group PS (FS%: 7.51 +/- 1.15 vs 13.21 +/- 1.49; [Ca(2+)]i max: 330.85 +/- 50.05 vs 498.16 +/- 14.07; both P < 0.01), and restored at least partially in CHF-T group. In CHF-C group, the left ventricular mRNA of NCX1 and PLB were significantly upregulated in comparing with PS group (RNCX1/beta-Actin: 0.51 +/- 0.12 vs 0.19 +/- 0.06, P < 0.01; RPLB/beta-Actin: 0.26 +/- 0.12 vs 0.20 +/- 0.08, P < 0.05), while SERCA2 mRNA was downregulated (0.48 +/- 0.10 vs 0.80 +/- 0.11, P < 0.01). The mRNA levels of NCX1 and SERCA2 in CHF-T group were between the CHF-C and PS group, and the differences of the latter two groups were significant (all P < 0.05). In CHF-C and CHF-T groups, the protein expression of NCX1 were 1.141 +/- 0.047 and 1.074 +/- 0.081 times of that in PS group respectively (both P < 0.05), and SERCA2 protein levels were 0.803 +/- 0.100 and 0.893 +/- 0.084 times of that in PS group respectively (both P < 0.05). The protein expression of NCX1 and SERCA2 in the CHF-C and CHF-T groups is significantly different (both P < 0.05).

CONCLUSIONACE inhibitor could improve cardiac function of failing heart through directly enhancing the contractility of single cardiomyocyte, and these effects are probably mediated by its roles in preventing the deleterious changes of calcium transients and calcium handling proteins in CHF.