[Effect of Chinoin-103 on Na+, K+-activated adenosine triphosphatase of the rat heart].

Effect of a new beta-blocking agent, a cardioselective aryl oxybutanolamine derivative, the Chinoin-103 on basal and total ATP-aze activities has been studied in total homogenizatum of rat heart. The effect has been compared to previous results of propranolol and to effect of practolol, respectively. It has been established that DL-Chinoin-103-similarly to DL-propranolol but in a little higher concentration--has significantly impeted both basal and total ATP-aze activities. Since in the nase of practolol similar effect was not obsreved and furthermore the effect could not be suspended by isoproterenol, the authors suppose that impediment of sarcolemmal ATP-aze activities cannot primarily be attributed to beta-blocking effect of compounds. Study of effect of racemic Chinoin-103 on enzymatic kinetic parameters of basal and total ATP-aze acticities has shown that primarily the reaction rate had decreased, affinity to substratum had not changed in the case of total ATP-aze and it has moderately decreased in the case of basal ATP-aze. The results of this publication has drawn attention to the fact that some beta-receptor blocking compounds may have other specific membrane effects besides antagonism on beta-receptors.