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Stimulation of arachidonic acid release by vasopressin in A7r5 vascular smooth muscle cells mediated by Ca2+-stimulated phospholipase A2 |
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| Authors: | Liu Yingjie Taylor Colin W |
| Institution: | Department of Pharmacology, Tennis Court Road, Cambridge CB2 1PD, UK. |
| Abstract: | Arachidonic acid (AA) regulates many aspects of vascular smooth muscle behaviour, but the mechanisms linking receptors to AA release are unclear. In A7r5 vascular smooth muscle cells pre-labelled with (3)H-AA, vasopressin caused a concentration-dependent stimulation of 3H-AA release that required phospholipase C and an increase in cytosolic Ca2+]. Ca2+ release from intracellular stores and Ca2+ entry via L-type channels or the capacitative Ca2+ entry pathway were each effective to varying degrees. Selective inhibitors of PLA2 inhibited the 3H-AA release evoked by vasopressin, though not the underlying Ca2+ signals, and established that cPLA2 mediates the release of AA. We conclude that in A7r5 cells vasopressin stimulates AA release via a Ca2+-dependent activation of cPLA2. |
| Keywords: | AA arachidonic acid 2-APB 2-aminoethoxydiphenyl borane AVP Arg8-vasopressin BAPTA 1 2-bis(2-aminophenoxy)ethane-N N N′N′-tetraacetic acid [Ca2+]i intracellular free [Ca2+] CCE capacitative Ca2+ entry cPLA2 cytosolic PLA2 DAG diacylglycerol EC50 concentration causing 50% of the maximal response IC50 concentration causing 50% of maximal inhibition iPLA2 Ca2+-independent PLA2 IP3 inositol 1 4 5-trisphosphate NCCE non-capacitative Ca2+ entry PA phosphatidic acid PC phosphatidylcholine PE phosphatidylethanolamine PKC protein kinase C PLA2 phospholipase A2 PLC phospholipase C PLD phospholipase D |
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