RESUMO
The effects of a frequently used sclerosing agent (Sotravarix 6%, main constituent polidocanol 60 mg/ml = 0.1 mol/l) on the electrical activity of the isolated perfused guinea pig heart and on transmembrane potential of isolated papillary muscle and sinus node were studied. Application of the sclerosing agent in a dilution of 1:40,000 (corresponding to polidocanol 2.6 x 10(-6) mol/l) caused a significant decrease in frequency (-27%) and (at constant frequency) a significant delay of the atrioventricular as well as of the intraventricular conduction (+105% or + 210%, resp. n = 4). These effects were only slightly reversible in a 30 min wash-out period. In the isolated papillary muscle, the sclerosing agent (dilution 1:10,000; polidocanol 1 x 10(-5) mol/l) decreased the maximum rate of rise of the action potential and shortened its duration, both by about 10%. In the isolated sinus node the same dilution decreased the spontaneous rate by about 8% mainly by reducing the diastolic depolarization rate (-18%). The effects of the sclerosing agent are attributable to the influence of polidocanol and consist in a blockade of the fast sodium channels (local anesthesia) and in additional inhibitory effects on calcium and/or potassium conductance.
