Effects of antiarrhythmic drugs on cardiac membrane conductances; a study using the Hodgkin and Huxley mathematical model.
A study in voltage clamp conditions of the modifications of the cardiac membrane conductances by quinidine sulfate has been carried out on frog atrial fibers by means of the double sucrose gap technique. The computation of the parameters related to the conductances has been done according to the Hodgkin and Huxley mathematical model proposed in 1952. The computed conductances concern the sodium conductance, the calcium conductance, and the total delayed conductance. A decrease of all of the studied conductances is observed in the presence of quinidine sulfate. This drug also mainly induced a slowing down of several activation, inactivation, and reactivation kinetics. The results obtained allow a more detailed explanation of the mechanism of action of quinidine sulfate in the membrane. Although quinidine is known to possess antiarrhythmic properties, the exact mechanisms of its action are not clear. The present study was therefore undertaken to provide some information on this point.
D000818:Animals; D001001:Anura; D002118:Calcium / Q000378:metabolism; D004553:Electric Conductivity; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects*; D008954:Models, Biological; D009206:Myocardium / Q000378:metabolism; D011802:Quinidine / Q000494:pharmacology*; D011893:Rana esculenta; D012964:Sodium / Q000378:metabolism
D012964:Sodium; D011802:Quinidine; D002118:Calcium