Shimamoto Y, Shimamoto H, Kwan C Y, Daniel E E
Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
Am J Physiol. 1993 Apr;264(4 Pt 2):H1300-6. doi: 10.1152/ajpheart.1993.264.4.H1300.
We investigated effects of three kinds of putative protein kinase C (PKC) inhibitors, calphostin C, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), and stauro-sporine, on aortic muscle contractions induced by KCl, phenylephrine, 12-O-tetradecanoylphorbol-13-acetate (TPA), and phorbol 12, 13-dibutyrate (PDBu). Calphostin C noncompetitively inhibited TPA-induced contractions in a concentration-dependent manner. At 10(-6) M, calphostin C completely abolished responses to TPA and also effectively inhibited PDBu-induced contractions. Such a concentration of calphostin C had no effect on KCl-induced contractions but decreased the maximal tension of phenylephrine-induced response curve by 35.3 +/- 6.6% H-7 (10(-5) M had little effect on TPA-induced contraction but significantly inhibited contractile responses to phenylephrine and KCl. Staurosporine (10(-8) M, 3 x 10(-8) M) inhibited contractile responses to KCl, phenylephrine, and TPA. We suggest that staurosporine and H-7, which are known to act on the catalytic domain of PKC carrying high degree of sequence homology with other protein kinases, are relatively nonselective for PKC. On the other hand, calphostin C acting on the regulatory domain of PKC, which is distinct from other protein kinases, may serve as a relatively more selective PKC inhibitor.
我们研究了三种假定的蛋白激酶C（PKC）抑制剂，即钙泊三醇C、1-（5-异喹啉磺酰基）-2-甲基哌嗪（H-7）和星形孢菌素，对氯化钾、去氧肾上腺素、12-O-十四烷酰佛波醇-13-乙酸酯（TPA）和佛波醇12,13-二丁酸酯（PDBu）诱导的主动脉肌肉收缩的影响。钙泊三醇C以浓度依赖性方式非竞争性抑制TPA诱导的收缩。在10^(-6) M时，钙泊三醇C完全消除了对TPA的反应，并且还有效抑制了PDBu诱导的收缩。如此浓度的钙泊三醇C对氯化钾诱导的收缩没有影响，但使去氧肾上腺素诱导的反应曲线的最大张力降低了35.3±6.6%。H-7（10^(-5) M）对TPA诱导的收缩影响很小，但显著抑制了对去氧肾上腺素和氯化钾的收缩反应。星形孢菌素（10^(-8) M，3×10^(-8) M）抑制了对氯化钾、去氧肾上腺素和TPA的收缩反应。我们认为，已知作用于与其他蛋白激酶具有高度序列同源性的PKC催化结构域的星形孢菌素和H-7对PKC相对非选择性。另一方面，作用于与其他蛋白激酶不同的PKC调节结构域的钙泊三醇C可能作为一种相对更具选择性的PKC抑制剂。
