St Louis P J, Sulakhe P V
Recent Adv Stud Cardiac Struct Metab. 1976;11:235-40.
Sarcolemma was isolated by fractionation of salt-extracted particles on two consecutive sucrose density gradients. Salt extraction of homogenates, rather than of washed particles, was found to preserve the activities of adenylate cyclase and ouabain-sensitive (Na+,-K+)-ATPase in the isolated sarcolemmal membranes. Purified sarcolemma contained substantial adenylate cyclase and guanylate cyclase activities that were stimulable by beta-adrenergic and muscarinic agonists, respectively. Significant ouabain-sensitive (Na+, K+)-ATPase activity as well as putative digitalis receptor activity was also present in sarcolemma. Cyclic nucleotide phosphodiesterases of sarcolemma, both cAMP- and cGMP-dependent, displayed positive cooperativity of substrate interactions; Ca2+ ions were found to increase the activity of the GMP-dependent enzyme.
通过在两个连续的蔗糖密度梯度上对盐提取颗粒进行分级分离来分离肌膜。发现对匀浆而非洗涤颗粒进行盐提取可保留分离的肌膜中腺苷酸环化酶和哇巴因敏感的（Na⁺，K⁺）-ATP酶的活性。纯化的肌膜含有大量的腺苷酸环化酶和鸟苷酸环化酶活性，分别可被β-肾上腺素能激动剂和毒蕈碱激动剂刺激。肌膜中还存在显著的哇巴因敏感的（Na⁺，K⁺）-ATP酶活性以及假定的洋地黄受体活性。肌膜的环核苷酸磷酸二酯酶，包括依赖cAMP和cGMP的，均表现出底物相互作用的正协同性；发现Ca²⁺离子可增加依赖GMP的酶的活性。
