Background:Relation between CARP expression and myocardial fibrosis has not been clearly defined yet. We compared expression of CARP and pattern of fibrosis in cardiac tissues of both normotensive and spontaneously hypertensive rats(SHR) that suffered with AD-induced cardiomyopathy. Methods:36 Wistar-Kyoto rats(WKY) and 36 SHR were divided into AD-treated and saline-treated groups. Immunohistochemical staining using synthesized CARP antibody and picrosirius staining was performed on left ventricular tissues. Positively stained areas were measured by using image analysis program(Image Pro-Plus 4.5) and CARP volume fractions(CARP-VF) and collagen volume fractions(CVF) were calculated. The expression of CARP and pattern of fibrosis was compared in the serial tissue sections of each groups.(Fig. Black rectangle shows CARP expressed region and black circle shows CARP unexpressed region) Results:1.The CARP-VF was 5.96짹5.11% in WKY and 9.04짹6.26% in SHR(P<0.05). The CARP-VF was 2.26짹4.74% in AD-treated WKY rats and 1.24짹4.32% in AD-treated SHR(P=0.32). 2.The CVF was 1.97짹1.28% in WKY and 4.32짹1.51% in SHR(P<0.05). The CVF was 3.41짹1.98% in AD-treated WKY and 8.77짹3.42% in AD-treated SHR(P<0.05). 3.AD treated SHR shows decreased CARP expression and increased myocardial fibrosis.(Fig. lower panel) Conclusion:These results suggest that CARP is closely related to myocardial fibrosis in pressure overloaded condition. Decreased CARP expression might be related to increased myocardial fibrosis in the pathogenesis of AD induced cardiomyopathy.