The accumulation of diacylglycerol and activation of protein kinase C induced by high K⁺ exposure in the frog skeletal muscle

The effects of high K⁺ exposure on the accumulation, of diacylglycerol (DAG) and on the activation of protein kinase C (PKC) have been studied in frog skeletal muscle. The endogenous DAG increased by treatment with 80mM K⁺ for different lengths of time. Correspondingly, high K⁺ exposure could induce a translocation of PKC. For instance, the membrane-associatad PKC activity (pmol/min·g muscle) was increased from the control value of 523±87 to 725±33 and 858±59 after 80mM K⁺ exposure for 2 and 60 minutes, while the cytosolic PKC activity was reduced from 548±35 to 307±20 and 254±46, respectively. The accumulation of DAG and the activation of PKC induced by high K⁺ exposure suggest a possible role of the pathway of DAG/PKC in the regulation of the excitation-contraction coupling in skeletal muscle fibres.