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Pflügers Archiv

, Volume 371, Issue 1–2, pp 71–76 | Cite as

Cardiac Purkinje fibres

[Ca2+]i controls steady state potassium conductance
  • Gerrit Isenberg
Exitable Tissues and Central Nervous Physiology

Summary

The influence of intracellular calcium concentration [Ca2+] i on the steady state membrane currentsi was studied in a range of clamp potentials between −20 and −100 mV. Injection of CaCl2 or Ca-EGTA (pCa ≤6) increasedi whereas injection of K-EGTA diminished it. The changes Δi were attributed to a change in steady state potassium conductance, gK∞, by four arguments: Δi was restricted to potentials negative to −20 mV and depended on clamp potential in an inward rectifying manner. Δi displayed a reversal potential, Erev, which followed log [K+]0 with 60 mV for a tenfold change. Since Erev obtained during Ca injection agreed with Erev observed during EGTA injection the potassium driving force had to be constant. WhengK was blocked by superfusion with 20 mM Cesium neither CaCl2 nor K-EGTA injection modifiedi.

Key words

Purkinje fibre Steady state membrane current Microinjection [Ca2+]i Calcium activated potassium conductance 

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Copyright information

© Springer-Verlag 1977

Authors and Affiliations

  • Gerrit Isenberg
    • 1
  1. 1.II. Physiologisches InstitutUniversität des SaarlandesHomburg/SaarFederal Republic of Germany

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