Mechanism of the contractile response to platelet-activating factor (PAF) of the rat stomach fundus. II. PAF-induced phosphatidylinositol turnover and desensitization.
1. Accumulation of [3H]-inositol phosphates (IPs) was slightly enhanced by PAF in a concentration-dependent manner, but the accumulation was very small as compared with that induced by carbachol. 2. The levels of [32P]-phosphatidic acid which is transformed from diacylglycerol (DAG) were increased by treatment with PAF or with carbachol. 3. PAF-induced contraction was significantly reduced by treatment with phorbol 12-myristate 13-acetate (PMA). 4. These results suggest that while PAF slightly stimulates the turnover of phosphatidylinositol (PI) in the rat stomach fundus, this response may not be responsible for the PAF-induced contractile response, and that the desensitization induced by repeated application of PAF may be due to the activation of protein kinase C.
Kamata
K
K
Department of Pharmacology, School of Pharmaceutical Sciences, Hoshi University, Tokyo, Japan.
Arai
Y
Y
Kasuya
Y
Y
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D005748:Gastric Fundus / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D006868:Hydrolysis; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D010712:Phosphatidic Acids / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D010972:Platelet Activating Factor / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; D010972:Platelet Activating Factor; D002217:Carbachol; D013755:Tetradecanoylphorbol Acetate