| Autor: |
Hata, Tomoji, Makino, Naoki, Nakanishi, Hironobu, Yanaga, Takashi |
| Zdroj: |
Molecular & Cellular Biochemistry; Nov1988, Vol. 84 Issue 1, p65-76, 12p |
| Abstrakt: |
The purpose of this study was to examine the effect of three classes of Ca antagonists, diltiazem, verapamil and nifedipine on Na-Ca exchange mechanism in the sarcolemmal vesicles isolated from canine heart. Na-Ca exchange and Ca pump (ATP-dependent Ca uptake) activities were assessed using the Millipore filtration technique. sarcolemmal vesicles used in this study are estimated to consist of several subpopulations wherein 23% are inside-out and 55% are right side-out sealed vesicles in orientation. The affect of each Ca antagonist on the Na-dependent Ca uptake was studied in the total population of sarcolemmal vesicles, in which none of the agents depressed the initial rate of Ca uptake until concentrations of 10 μM were incubated in the incubation medium. However, when sarcolemmal vesicles were preloaded with Ca via ATP-dependent Ca uptake, cellular Ca influx was depressed only by verapamil (28%) at 1 μM in the efflux medium with 8 mM Na. Furthermore, inhibition of Ca efflux by verapamil was more pronounced in the presence of 16 mM Na in the efflux medium. The order of inhibition was; verapamil > diltiazem > nifedipine. These results indicate that same forms of Ca-antagonist drugs may affect the Na-Ca exchange mechanism in the cardiac sarcolemmal vesicles and therefore we suggest this site of action may contribute to their effects on the myocardium. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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