Vasopressin activates phospholipase D through pertussis toxin-insensitive GTP-binding protein in aortic smooth muscle cells: function of Ca²⁺/calmodulin

Abstract

In the present study, we examined the effect of vasopressin (AVP) on phosphatidylcholine-hydrolyzing phospholipase D activity in primary cultured rat aortic smooth muscle cells. AVP stimulation of choline formation was dose dependent. The time-course was quite different from those of inositol phosphates. The effect of AVP on the formation of inositol phosphates (EC50 was 3 nM) was more potent than that on the formation of choline (EC50 was 30 nM). 12-O-Tetradecanoylphorbol-13-acetate (TPA), an activator of protein kinase C (PKC), stimulated the formation of choline. However, 4 alpha-phorbol 12,13-didecanoate, which is inactive for PKC, had little effect. Staurosporine, an inhibitor of protein kinases, which inhibited the TPA-induced formation of choline, had little effect on the AVP-induced formation of choline. Neither calphostin C, a highly specific PKC inhibitor, nor PKC down-regulation with TPA affected AVP-induced formation of choline. A combination of AVP and TPA additively stimulated the formation of choline. The depletion of extracellular Ca2+ by (ethylenebis(oxyethylenenitrilo)tetraacetic acid significantly reduced the AVP-induced formation of choline. W-7, an antagonist of calmodulin, inhibited the AVP-induced formation of choline in a dose-dependent manner. NaF, an activator for GTP-binding protein (G-protein), stimulated the formation of choline. However, the formation of choline by a combination of AVP and NaF was not additive. Pertussis toxin had little effect on the AVP-induced formation of choline.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasopressin-stimulated Ca2+spiking in vascular smooth muscle cells involves phospholipase D

“…Similar methods were used by Ito and colleagues (11) who also found that the release of 3 H radioactivity was stimulated by very low concentrations of AVP (EC 50 ϳ 50 pM). However, reports that AVP stimulates PLD in VSM [including A7r5 cells (13,15,23)] led us to investigate whether some of the radioactivity may be in the form of PA (the product of PLD), which may contain the labeled fatty acyl moiety. We used TLC to separate the lipid products and then determined the radioactivity that comigrates with purified AA or PA standards.…”

Vasopressin Stimulates Na-dependent Phosphate Transport and Calcification in Rat Aortic Smooth Muscle Cells

“…V1a receptor is located mainly in the central nervous system and cardiovascular organs including VSMC, while V1b and V2 are located in the central nervous system and kidney, respectively. As for intracellular signaling mechanisms, it has been reported that AVP mobilizes intracellular Ca 2+ and stimulates protein kinase C (PKC) through the activation of phospholipase (PL) C and PLD in VSMC [15][16][17], which is involved in the mechanism of AVP-induced proliferation of these cells [18]. Other important signaling pathways to mediate the mitogenic and differentiation processes are tyrosine kinases.…”

Somatostatin Receptors Signal through EFA6A-ARF6 to Activate Phospholipase D in Clonal β-Cells

“…A plethora of GPCR agonists have been shown to stimulate PLD activity. Angiotensin II (24), bradykinin (25), carbachol (26), lysophosphatidic acid (27), gonadotropin-releasing hormone (28), vasopressin (29), endothelin (30), thyrotropin (31), and prostaglandin F 2␣ (32) are examples of the prevalent nature of GPCR-mediated stimulation of PLD. GPCRs can stimulate PLD through phospholipase C (PLC)-dependent signaling pathway.…”