Activation of multiple mechanisms including phospholipase D by endothelin-1 in rat aorta

Abstract

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.

Sevoflurane reduces endothelium-dependent vasorelaxation: role of Superoxide anion and endothelin

“…9,17 ET-1 is a 21-aminoacid peptide that binds to ETA-type receptors expressed on smooth muscle cells inducing a vasoconstrictor response. 18,19 Interestingly, ET-1 is also capable of stimulating the production of superoxide anion by several types of cells. 20,21 In our study, a specific antagonist of the ETA-type receptors, BQ-123, normalized the endotheliumdependent vasorelaxing response impaired by sevoflurane suggesting that vasoconstriction related to ET-1 could be counterbalancing the NO-dependent vasorelaxing system in sevoflurane-incubated aortic segments.…”

Endothelin‐1 stimulated phospholipase D in A10 vascular smooth muscle derived cells is dependent on tyrosine kinase Evidence for involvement in stimulation of mitogenesis

“…This mitogenic activity has been associated with the stimulated expression of the protooncogenes c-fis and c-myc in both smooth muscle cells [2] and fibroblasts [4]. ET-l acting at ET, receptors is known to stimulate both phospholipase C (PLC) [3,4] and phospholipase D (PLD) [5] in vascular smooth muscle cells. Phosphatidic acid is the primary lipid product of PLD, and it (or its lyso derivative) may be mitogenic in its own right [6,7].…”

Effects of angiotensin II and endothelin-1 on platelet aggregation and cytosolic pH and free Ca2+ concentrations in essential hypertension.

“…Phospholipase D, which is known to be activated by endothelin-1 and which will generate diacylglycerol and thus activate protein kinase C independently of phospholipase C, could play a role in modulating platelet pH without significantly altering cytosolic calcium. 43 Intracellular alkalinization induced by Ang II and endothelin-1 are probably related to stimulation of the Na + -H + exchanger. We have shown that in the presence of a highly specific Na + -H + exchange blocker, the normal alkalinization responses to Ang II and endothelin-1 were abolished.…”