Abstract
In rat myometrium labeled with [3H]myristic acid, endothelin (ET)-1 via ETA receptors stimulated, in the presence of 0.3% butanol, the formation of [3H]phosphatidylbutanol ([3H]PBut) as a result of phospholipase D activity. Fluoroaluminates increased [3H]PBut generation, which indicated that a heterotrimeric G protein was involved. The ET-1 effect was insensitive to pertussis toxin and was rapidly desensitized. The calcium ionophore ionomycin as well as 4β-phorbol 12-myristate-13-acetate and 4β-phorbol 12,13-dibutyrate also stimulated [3H]PBut production. Protein kinase C (PKC) inhibition, particularly with Ro-31–8220, and down-regulation of PKC by 4β-phorbol 12-myristate-13-acetate, abrogated 4β-phorbol 12,13-dibutyrate responses but partially reduced (50%) ET-1 and ionomycin stimulatory effects. [3H]PBut production induced by ionomycin depended on Ca++ influx, whereas that induced by 4β-phorbol 12,13-dibutyrate did not. Decrease of extracellular Ca++ partially reduced (60%) ET-1 stimulation that was additionally attenuated (75%) by chelerythrine, a PKC inhibitor. The data indicate that in myometrium, phospholipase D was activated by PKC and Ca++, which both contribute at least partially to ET-1-mediated phospholipase D activation.
Footnotes
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Send reprint requests to: Simone Harbon, Laboratoire d’Endocrinologie et Régulations Cellulaires, CNRS URA 1131, Bât 432, Université Paris Sud, 91405 Orsay Cedex, France.
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↵1 This work was supported by grants from the CNRS (URA 1131).
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↵2 These authors contributed equally to this work.
- Abbreviations:
- PLD
- phospholipase D
- ET
- endothelin
- PBut
- phosphatidylbutanol
- PMA
- 4β-phorbol 12 myristate-13-acetate
- PDBu
- 4β-phorbol 12,13-dibutyrate
- PKC
- protein kinase C
- OAG
- oleoyl-2-acetyl-sn-glycerol
- PLC
- phospholipase C
- PtdInsP2
- phosphatidylinositol 4,5-bisphosphate
- PA
- phosphatidic acid
- PC
- phosphatidylcholine
- PS
- phosphatidylserine
- PI
- phosphatidylinositol
- PE
- phosphatidylethanolamine
- InsP3
- inositol 1,4,5 trisphosphate
- EGTA
- ethyleneglycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid
- Received September 24, 1996.
- Accepted December 9, 1996.
- The American Society for Pharmacology and Experimental Therapeutics
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