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Journal of Korean Neurosurgical Society 1994;23(12): 1359-1368. |
Phorbol Ester Modulates th Action of Acetylcholine in Rabbit Carotid Artery. |
Yong Lae Nho, Sang Ho Lee, Young Woo Lee |
1Department of Neurosurgery, College of Medicine, Pusan National University, Pusan, Korea. 2Department of Physiology, College of Medicine, Pusan National University, Pusan, Korea. |
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ABSTRACT |
Authors studied the regulatory mechanism of protein kinase C on the action of acetylcholine in rabbit carotid artery. The arterial rings were myographied isometrically in an isolated organ bath. In this study, acetylcholine relaxed phenylephrine-induced contraction of rabbit carotid artery in the presence of endothelium. In the pretreatment of methylene blue or nitro-L-arginine, the action of acetylchioline was reduced. Pretreatment of phorbol 12-myristate 13-acetate(PMA) attenuated the action of acetylcholine, but PMA did not attenuated it in the presence of staurosporine, suggesting that protein kinase C suppressed the action of acetylcholine. The potency of phorbol ester on the action of acetylcholine was PMA>phorbol 12, 13-dibutyrate(PDBu)>phorbol 12,13-diacetate(PDA), but the direct effect of phorbol on the contraction of arterial rings was PDBu>PMA>PDA. This implied that protein kinase C involved in the contraction of smooth muscle and the attenuation of the action of acetylcholine were different.
PMA did not affect on A23187- and sodium nitroprusside-induced vasorelaxation. Acetylcholine increased tissue cGMP contents, which was reduced by PMA.
These results suggest that in rabbit carotid artery protein kinase C reduce acetylcholine-stimuated endothelium derived relaxing factor(EDRF) release by affecting membrane receptor, and do not affect on the function of EDRF and cGMP production in the smooth muscle. |
Key Words:
Phorbol ester; Acetylcholine; Protein kinase C; Contraction of smooth muscle; Endothelium derived relaxing factor(EDRF) |
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