Second messengers involved in the muscarinic control of the heart: the role of the phosphoinositide response.
Two heart muscarinic responses are compared, the reduction of cyclic AMP concentration and the hydrolysis of phosphoinositides. It is suggested that the former is more important physiologically, since the latter is a slow response requiring much higher agonist concentrations. Inositol trisphosphate released from phosphoinositides is unlikely to produce a positive inotropic effect by releasing calcium from the sarcoplasmic reticulum. However, long term muscarinic effects may involve activation of protein kinase C by diacylglycerol released from phosphoinositides.
Hawthorne
J N
JN
Department of Biochemistry, University of Nottingham Medical School, Queen's Medical Centre, UK.
Simmonds
S H
SH
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D006868:Hydrolysis; D009200:Myocardial Contraction / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism*; D010277:Parasympathomimetics / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D015290:Second Messenger Systems
D010277:Parasympathomimetics; D010716:Phosphatidylinositols; D011976:Receptors, Muscarinic; D000242:Cyclic AMP