Activation of multiple mechanisms including phospholipase D by endothelin-1 in rat aorta.
This study investigated the cellular mechanisms underlying the endothelin-1 (ET-1)-induced contraction of rat aorta with focus on the involvement of phospholipase D (PLD). Preincubating rat aorta in Ca(2+)-free solution reduced the contraction by 80%, whereas diltiazem (10 microM), a voltage-operated Ca2+ channel blocker, caused only a small reduction (27%, P less than 0.05) of the contraction. In myo-[3H]inositol-labeled aorta, ET-1 stimulated the formation of [3H]inositol bisphosphate and [3H]inositol trisphosphate, indicating the activation of phospholipase C (PLC). In aorta labeled with 32PO4, [3H] myristic acid or [32P]lyso-platelet-activating factor followed by exposure to ethanol (0.5%), ET-1 stimulated phosphatidylethanol (PEt) production, suggesting that ET-1 activates PLD. The PEt response was not attenuated by staurosporine (ST, 0.1 microM), an inhibitor of protein kinase C (PKC) but was inhibited by removal of Ca2+. The ET-1-induced PEt response was at least additive to that induced by phorbol 12-myristate 13-acetate (1 microM). ET-1 also stimulated the release of 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) into the tissue medium. Unlike the PEt responses, the 6-keto-PGF1 alpha response could be inhibited by ST. Removal of Ca2+ abolished the response. These results suggest that 1) ET-1 activates multiple cellular mechanisms including PLC, PLD, and the arachidonate cascade; 2) PKC activation may not be essential for the ET-1 activation of PLD but may play an important role in the ET-1 stimulation of 6-keto-PGF1 alpha release; and 3) Ca2+ is an important factor in the ET-1-induced PLD activity and 6-keto-PGF1 alpha release.
Liu
Y
Y
Department of Physiology, School of Medicine, University of Missouri, Columbia 65212.
Geisbuhler
B
B
Jones
A W
AW
D015121:6-Ketoprostaglandin F1 alpha / Q000378:metabolism; D000818:Animals; D001011:Aorta / Q000201:enzymology*; D002118:Calcium / Q000502:physiology; D016232:Endothelins / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D020404:Glycerophospholipids; D006868:Hydrolysis; D008297:Male; D010712:Phosphatidic Acids / Q000096:biosynthesis; D010716:Phosphatidylinositols / Q000378:metabolism; D010739:Phospholipase D / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D014661:Vasoconstriction
D016232:Endothelins; D020404:Glycerophospholipids; D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; C051521:phosphatidylethanol; D015121:6-Ketoprostaglandin F1 alpha; D010739:Phospholipase D; D002118:Calcium