Arachidonic acid activates the noncapacitative entry of Ca2+ during [Ca2+]i oscillations.
Current models for agonist-activated Ca2+ entry in nonexcitable cells focus on the capacitative mechanism where entry is activated as a downstream result of the sustained depletion of agonist-sensitive stores without any direct requirement for inositol phosphates. This mechanism has been shown to be important for the sustained Ca2+ signals seen in a variety of nonexcitable cells under conditions of maximal stimulation. In contrast, relatively little attention has been given to Ca2+ entry under more physiological levels of agonist where, for example, oscillating Ca2+ responses are common. In recent studies using cells from the exocrine avian nasal gland, we have shown that agonist-activated Ca2+ entry under these conditions demonstrates properties that are inconsistent with current versions of the capacitative model. We now report that activation of this novel noncapacitative Ca2+ entry is via a distinct signaling pathway involving an agonist-induced, phospholipase A2-mediated generation of arachidonic acid.
Shuttleworth
T J
TJ
Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D044182:Benzylisoquinolines; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D004372:Ducks; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D015640:Ion Channel Gating; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000378:metabolism; D054467:Phospholipases A2; D011506:Proteins / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism
D000470:Alkaloids; D044182:Benzylisoquinolines; D002121:Calcium Channel Blockers; D011506:Proteins; D011976:Receptors, Muscarinic; C055324:phospholipase A2-activating protein; D016718:Arachidonic Acid; C009438:tetrandrine; D004533:Egtazic Acid; D015544:Inositol 1,4,5-Trisphosphate; D002217:Carbachol; D010741:Phospholipases A; D054467:Phospholipases A2; D010738:Type C Phospholipases; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium