| Abstrakt: |
Varying ionic composition of outher medium and applying specific agents the role of fast and slow systems of entering currents in the accommodation of cats ventricular fibres has been studied. In potential region close to the level of resting potential (membrane depolarization no larger than 20-30mv), accomodation mainly depends on fast sodium currents. It is inhibited with a rise of this current (akonitin 0.1--1 mg) and, on the contrary, it increases when it gets weaker (novacain 2--5 mM). In the region of more positive potentials (membrane depolarization more than by 30 mv) the accommodation is mainly determined by the slow NA--Ca-systems of channels. The agents which strengthen NA--Ca--current (Si2+--5mM, Ca2+--10mM, Ba2+--0.1 mM) reduce the accommodation in the activation region of the Na--Ca--system. The agents which weaken the slow current (Mn2+--3 mM, isoptin--2+5 mg/l, inderal--2 mg/l) produce an opposite effect. |
