ESTIMATION OF THE MEMBRANE TIME CONSTANT IN THE 2-DIMENSIONAL RC MEDIUM

For analysis of intercellular communication and excitation spread processes in the myocardium it is essential to know the cable parameters - the space constant of electrotonic decay in the longitudinal and transverse fiber orientations (lambda-x, lambda-y) and the time constant of the electrogenic membrane (tau-m). Evaluation of tau-m is possible by defining the dependence of time (t1/2), during which the electrotonic potential reaches half the stationary amplitude, upon the distance (r) from the registration point to the point of delivering the rectangular intracellular current. It has been revealed that the dependence of t1/2 on r in the one-dimensional and three-dimensional media is expressed by first order asymptotic equations. This study shows that the dependence of t1/2 on r in the two-dimensional medium is also linear: t1/2 = tau-m(r)/2-lambda.