Effect of oxyphenamone on sodium and calcium channels of guinea pig myocardial cells / 药学学报

ABSTRACT

<p><b>AIM</b>To investigate the mechanism of the positive inotropic effect of oxyphenamone.</p><p><b>METHODS</b>With the patch clamp technique and whole cell recording, the sodium and L type calcium currents of myocytes isolated from ventricular myocardium of adult guinea pigs were studied.</p><p><b>RESULTS</b>5 - 50 micromol x L(-1)-oxyphenamone not only significantly inhibited Na+ current, but also promoted the process of inactivation and prolonged the recovery time of the inactivation. The action of oxyphenamone on L type calcium channel was dual. The inward calcium current was increased with 2 - 10 micromol x L(-1) oxyphenamone but decreased when the concentration of the drug was elevated to 20 - 50 micromol x L(-1).</p><p><b>CONCLUSION</b>The mechanism of the positive inotropic effect of oxyphenamone is neither due to the activation of sodium channel nor entirely depending upon the activation of L type calcium channel. The effects of inhibiting sodium current and, at a high concentration, blocking L type calcium current suggest that oxyphenamone may have an antiarrhythemia action.</p>