ABSTRACT
BACKGROUND AND OBJECTIVES: Cardiac ankyrin repeat protein (CARP) is an embryonic nuclear protein, and its expression is increased under conditions of pressure or volume overload and also in the failing heart. Adriamycin is a cardiotoxic chemotherapeutic agent, and it suppresses the expression of CARP. We compared the expressions of CARP in the myocardium of normotensive rats and spontaneously hypertensive rats (SHRs) that suffered with adriamycin-induced cardiomyopathy. MATERIALS AND METHODS: 36 Wistar-Kyoto rats (WKYs) and 36 SHRs were divided into the adriamycin-administered and saline-administered groups. Adriamycin (2.5 mg/kg) and saline were injected intraperitoneally twice a week for 3 weeks. All the animals were sacrificed 3 weeks after the last injection. Immunohistochemical staining was performed on the left ventricles with using synthesized polyclonal CARP antibody. The positively stained areas were measured by using an image analysis program, and the CARP volume fractions (CaVF) were calculated. RESULTS: CARP was diffusely expressed in the cytoplasm of the myocytes in all the groups. The number of CARP expressing cells was increased in the SHRs. The CaVFs was 5.96+/-5.11% in the WKYs and it was 9.04+/-6.26% in the SHRs (p=0.014). The CaVF was 2.26+/-4.74% in the adriamycin-administered WKYs and it was 1.24+/-4.32% in the adriamycin-administered SHRs (p=0.32). The adriamycin-administered WKYs and SHRs showed significantly decreased CARP expressions, as compared to the saline-administered groups (p<0.001 and p<0.001, respectively). CONCLUSION: These results suggest that CARP is closely related to the pathogenesis of adriamycin-induced cardiomyopathy and it probably plays a pivotal role for the adriamycin cardiac toxicity observed in hypertensive rats.