Dynamic of alpha-1-adrenoceptor mediated degradation of membrane phospholipids in cultured rat cardiomyocytes.
In many cell types, agonists can stimulate both phosphoinositide (PtdIns) and phosphatidylcholine (PC) hydrolysis by activating specific phospholipases. Using cultures of neonatal rat cardiomyocytes we have verified the existence of an alpha 1-adrenoceptor mediated hydrolysis of PtdIns and PC. PtdIns breakdown, evaluated as inositol phosphate production, occurred in the early phase of cell stimulation, while PC hydrolysis, evaluated as choline metabolite production, was evidenced at longer stimulation times. The appearance of a delayed peak of choline phosphate and the invariance of free choline in the intracellular water phase strongly suggest the involvement of a specific PC-phospholipase C, generating choline phosphate and diacylglycerol, the activator of protein kinase C. Since it is plausible that various metabolites of signal-induced degradation of membrane phospholipids may take part in long term physiological responses, PC breakdown could be involved in cellular mechanisms that require prolonged protein kinase C activation.
Bordoni
A
A
Department of Biochemistry G. Moruzzi, University of Bologna, Italy.
Biagi
P
P
Rossi
C A
CA
Hrelia
S
S
D000818:Animals; D000831:Animals, Newborn; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D006321:Heart / Q000187:drug effects; D007294:Inositol / Q000378:metabolism; D007295:Inositol Phosphates / Q000378:metabolism; D007700:Kinetics; D008563:Membrane Lipids / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology*; D010713:Phosphatidylcholines / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000502:physiology*; D015290:Second Messenger Systems / Q000502:physiology; D013997:Time Factors
D007295:Inositol Phosphates; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010716:Phosphatidylinositols; D010743:Phospholipids; D018340:Receptors, Adrenergic, alpha-1; D010656:Phenylephrine; D007294:Inositol