Conduction between isolated rabbit Purkinje and ventricular myocytes coupled by a variable resistance.

Academic Article

Abstract

  • Conduction at the Purkinje-ventricular junction (PVJ) demonstrates unidirectional block under both physiological and pathophysiological conditions. Although this block is typically attributed to multidimensional electrotonic interactions, we examined possible membrane-level contributions using single, isolated rabbit Purkinje (P) and ventricular (V) myocytes coupled by an electronic circuit. When we varied the junctional resistance (Rj) between paired V myocytes, conduction block occurred at lower Rj values during conduction from the smaller to larger myocyte (115 +/- 59 M omega) than from the larger to smaller myocyte (201 +/- 51 M omega). In Purkinje-ventricular myocyte pairs, however, block occurred at lower Rj values during P-to-V conduction (85 +/- 39 M omega) than during V-to-P conduction (912 +/- 175 M omega), although there was little difference in the mean cell size. Companion computer simulations, performed to examine how the early platea currents affected conduction, showed that P-to-V block occurred at lower Rj values when the transient outward current was increased or the calcium current was decreased in the model P cell. These results suggest that intrinsic differences in phase 1 repolarization can contribute to unidirectional block at the PVJ.
  • Authors

    Published In

    Keywords

  • Animals, Calcium, Cell Size, Computer Simulation, Electric Conductivity, Electric Impedance, In Vitro Techniques, Male, Models, Cardiovascular, Myocardium, Neural Conduction, Purkinje Fibers, Rabbits, Ventricular Function
  • Digital Object Identifier (doi)

    Author List

  • Huelsing DJ; Spitzer KW; Cordeiro JM; Pollard AE
  • Start Page

  • H1163
  • End Page

  • H1173
  • Volume

  • 274
  • Issue

  • 4