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 |
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| Affiliation: | Department of Pharmacology, Tennis Court Road, Cambridge CB2 1PD, UK. |
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| 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. |
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| 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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