Forskolin inhibits tension development in detergent-treated cardiac muscle fibers

Summary In detergent-treated cardiac muscle fibers, forskolin, a potent activator of adenylate cyclases, inhibits tension development elicited with submaximal Ca²⁺] and increases incorporation of³²P into troponin-I. A similar reduced tension development has been observed after treatment with cAMP or the catalytic subunit of the cAMP-dependent protein kinase. It is concluded that these fibers still contain much of the enzyme cascade involved in evoking a contractile response to \-adrenergic stimulation.Acknowledgment. The authors thank Dr H. Metzger, Hoechst AG, Frankfurt (FRG) for the gift of forskolin. The excellent technical assistance of Mrs Doris Eubler and the support by the Deutsche Forschungsgemeinschaft (SFB 90) are gratefully acknowledged.