Alpha-1-adrenergic stimulation of phosphoinositide breakdown in cultured neonatal rat ventricular myocytes

Summary The regulation of and the intracellular events following a,-adrenergic receptor stimulation in the myocardium still remain to be disclosed. The effect of ₁- adrenergic stimulation on phosphoinositide breakdown was studied in cultured neonatal rat ventricular myocytes. Phenylephrine (30 M) stimulated inositolphosphates formation, but only in the presence of 10 mM LiCl this could be measured. The increase was antagonized by prazosin (1 M) but not by propranolol (1 M). The variability in proportional distribution of the three inositolphosphates is discussed.Abbreviations PIP₂ Phosphatidylinositol 4,5-bisphosphate - PI Phosphatidylinositol - IP₃ Inositol 1,4,5,-bisphosphate - IP₂ Inositol 1,4-bisphosphate - IP₁ Inositol 1-monophosphate - DG Diacylglycerol - PKC Calcium/phospholipid-dependent protein kinase - PhE Phenylephrine.