Vasopressin activates phospholipase D through pertussis toxin-insensitive GTP-binding protein in aortic smooth muscle cells: function of Ca2+/calmodulin.
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)
Miwa
M
M
First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Kozawa
O
O
Suzuki
A
A
Watanabe
Y
Y
Shinoda
J
J
Oiso
Y
Y
D000818:Animals; D001011:Aorta / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D002478:Cells, Cultured; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D037342:Pertussis Toxin; D010739:Phospholipase D / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D014667:Vasopressins / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella
D002147:Calmodulin; D010566:Virulence Factors, Bordetella; D014667:Vasopressins; D037342:Pertussis Toxin; D010739:Phospholipase D; D019204:GTP-Binding Proteins; D002118:Calcium