Barium-induced blockade of the inward rectifier in calf Purkinje fibres

Pflugers Arch. 1984 Dec;402(4):446-53. doi: 10.1007/BF00583946.


The Ba-induced blockade of iK1 in calf Purkinje fibres was studied in the low concentration range (3-1,000 microM). The results showed that the blockade induced by hyperpolarizations was time-dependent, and that the rate of blockade increased with the Ba concentration and the negative pulse amplitude. At Ba concentrations higher than 1 mM the time course of iK1 blockade was not separable from the capacity transient. At these concentrations, and in a limited voltage range, the Ba-sensitive instantaneous current displayed a marked inward rectification and behaved with external K as expected for a pure K+ current, suggesting that under these conditions the only current affected by Ba was iK1. The Ba-sensitive current deceased with time during hyperpolarizations even when high external K was present, indicating that a voltage-dependent inactivation process could be at least in part responsible for the observed current decline.

MeSH terms

  • Animals
  • Barium / pharmacology*
  • Cattle
  • Heart Conduction System / drug effects*
  • Ion Channels / drug effects*
  • Potassium / metabolism
  • Purkinje Fibers / drug effects*
  • Purkinje Fibers / metabolism
  • Time Factors


  • Ion Channels
  • Barium
  • Potassium