Carbamoylcholine-induced accumulation of inositol mono-, bis-, tris- and tetrakisphosphates in isolated cardiac myocytes from adult rats.

The effect of carbamoylcholine on the phosphoinositide cycle in isolated ventricular myocytes from adult rats was studied. Separation of the phosphoinositides by high-performance thin-layer chromatography showed a constant ratio of incorporation of myo-[2-3H]inositol into phosphatidylinositol, phosphatidylinositol 4-monophosphate and phosphatidylinositol 4,5-bisphosphate of cultured cardiac myocytes after at least 2 h. Carbamoylcholine caused a dose-dependent and time-dependent accumulation of inositol mono-, bis- and trisphosphates, which was antagonized by atropine. Using anion-exchange HPLC the existence of inositol 1,4,5-trisphosphate, inositol 1,3,4-triphosphate and inositol 1,3,4,5-tetrakisphosphate was confirmed in rat ventricular myocytes. Inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate accumulated within 20 s, while inositol 1,3,4-trisphosphate, inositol 1,4-bisphosphate and inositol monophosphate increased within 5 min.