RESUMO
Index of accommodation of 32 frog sciatic nerves was studied with exponentially rising currents. Ethanol was mixed with normal Ringer's solution at the following concentrations: 42, 85, 171, and 513 mM. We found a significant increase in the accommodation index. The results were attributed to the sodium conductance change and to a drop in membrane potential elicited by ethanol. The loss of the breakdown in the nerve accommodation curve was interpreted as the ethanol acting mainly on the thinner nerve fibres rather than on the large fibres.
Assuntos
Etanol/farmacologia , Nervo Isquiático/efeitos dos fármacos , Potenciais de Ação/efeitos dos fármacos , Animais , Anuros , Condução Nervosa/efeitos dos fármacosRESUMO
The action of ethanol on compound action potential, refractory periods and chronaxia are analyzed in 28 isolated sciatic nerves of toads. 85 mM ethanol increases the compound action potential and decreases the refractory periods. 342 and 513 mM ehtanol decrease the compound action potential and increase the absolute and relative refractory periods. These biphasic effects are discussed in relation with changes in Na+ and K+ permeabilities and to the greater sensitivity of thin fibers to the chemicals.