Forskolin inhibits tension development in detergent-treated cardiac muscle fibers.

In detergent-treated cardiac muscle fibers, forskolin, a potent activator of adenylate cyclases, inhibits tension development elicited with submaximal [Ca2+] and increases incorporation of 32P 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 beta-adrenergic stimulation.