Patel A I, Diamond J
Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, B.C., Canada.
J Pharmacol Exp Ther. 1997 Nov;283(2):885-93.
It is generally accepted that cGMP mediates the vascular relaxant effects of nitrovasodilators such as sodium nitroprusside (SNP) and nitroglycerin (NTG). It has been suggested that the relaxant effects of cGMP are mediated via activation of a specific, cGMP-dependent protein kinase (PKG). The objective of this study was to determine whether PKG can be activated by SNP and by NTG in intact strips of rabbit aorta and, if so, whether a good correlation exists between activation of PKG and relaxation of the arteries by the nitrovasodilators. PKG activity was measured by means of a recently described assay using a peptide substrate, BPDEtide, that exhibits good sensitivity and specificity for PKG compared with other protein kinases. Verification of the specificity of the assay for PKG was obtained using MonoQ chromatography to resolve soluble extracts of the rabbit aorta and subsequent immunoblotting to identify the kinase by means of a PKG-specific antibody. The role of PKG in vascular relaxation was investigated by simultaneously monitoring the effects of SNP and NTG on cGMP levels, PKG activity ratios and tension in isolated strips of rabbit aorta exposed to varying concentrations of the nitrovasodilators for varying times. The results indicate that PKG can be activated in a concentration- and time-dependent manner by both SNP and NTG in intact vascular preparations and that reasonably good correlations exist between PKG activation and relaxation in these experiments. Although a causal relationship between the two parameters has not been definitely established, these results are consistent with the proposed role for PKG as a mediator of the vascular relaxant effects of cGMP-elevating agents such as SNP and NTG.
一般认为，环磷酸鸟苷（cGMP）介导硝血管扩张剂如硝普钠（SNP）和硝酸甘油（NTG）的血管舒张作用。有人提出，cGMP的舒张作用是通过激活一种特定的、依赖cGMP的蛋白激酶（PKG）介导的。本研究的目的是确定在兔主动脉完整条带中PKG是否能被SNP和NTG激活，如果可以，PKG的激活与硝血管扩张剂引起的动脉舒张之间是否存在良好的相关性。PKG活性通过最近描述的一种使用肽底物BPDEtide的测定方法来测量，与其他蛋白激酶相比，该底物对PKG具有良好的敏感性和特异性。使用MonoQ色谱法分离兔主动脉的可溶性提取物，随后进行免疫印迹，通过PKG特异性抗体鉴定激酶，从而验证该测定方法对PKG的特异性。通过同时监测SNP和NTG对暴露于不同浓度的硝血管扩张剂不同时间的兔主动脉分离条带中的cGMP水平、PKG活性比率和张力的影响，研究了PKG在血管舒张中的作用。结果表明，在完整的血管制剂中，PKG可被SNP和NTG以浓度和时间依赖性方式激活，并且在这些实验中PKG激活与舒张之间存在合理的良好相关性。尽管尚未明确确定这两个参数之间的因果关系，但这些结果与PKG作为cGMP升高剂如SNP和NTG的血管舒张作用介质的 proposed role一致。 （注：这里“proposed role”直译为“提出的作用”，结合语境可能是指前文提到的那种作用，可根据实际情况进一步优化表述）
