Phorbol ester‐induced protein phosphorylation and contraction in sphincter smooth muscle of rabbit iris

[摘要]

Phorbol 12,13-dibutyrate (PDBu) was employed in studies designed to determine the role of C-kinase in muscle contraction in the iris sphincter. PDBu induced MLC phosphorylation and contraction in a dose- and time-dependent manner. Maximum responses exerted by PDBu were about 50–60% of that obtained with CCh, and were totally dependent on the presence of extracellular Ca²⁺. PDBu had no effect on basal IP₃ levels, however it blocked the CCh-stimulated accumulation of IP₃. PDBu-induced effects were potentiated by ionomycin, and inhibited by the C-kinase antagonist H-7. These results provide further evidence for the involvement of C-kinase in mediating the sustained phase of the contractile response in the iris sphincter.

[学科分类] 生物化学/生物物理

[关键词] Protein kinase;Phosphorylation;Myosin light chain;Muscle contraction;Phorbol ester;Ca2+;(Iris sphincter smooth muscle);PDBu;phorbol 12;13-dibutyrate;PMA;phorbol-12-myristate-13-acetate;PIP2;phosphatidylinositol 4;5-bisphosphate;DG;1;2-diacylglycerol;IP3;inositol trisphosphate;MLC;myosin light chain;CCh;carbachol;H-7;1-(5-isoquinolinesulfonyl)-2-methylpiperazine