Giant excised cardiac sarcolemmal membrane patches: sodium and sodium-calcium exchange currents

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Abstract

A tightly-sealed cardiac sarcolemmal patch preparation of large diameter (10-16 μm with 5-25 GΩ seals) has been developed to study regulation of selected electrogenic mechanisms. Formation of a large readily accessible membrane surface area is achieved by incubating freshly isolated myocytes in a high KCl/zero calcium solution, which promotes separation of sarcolemma from myofilaments. The formation of large-diameter, high resistance seals is facilitated by depositing a neutral hydrocarbon film on electrode tips. Sodium currents in excised patches are stable for patch life-times of 15-40 min with peak current densities of 120 to 350 μA/cm2. Outward sodium-calcium exchange current is identified by its specific dependence on external calcium and internal sodium, inhibition by cobalt and dichlorobenzamil, and activation by <0.1 μM internal free, calcium. Maximum exchange current density is >20 μA/cm2.

Original languageEnglish (US)
Pages (from-to)247-249
Number of pages3
JournalPflügers Archiv European Journal of Physiology
Volume415
Issue number2
DOIs
StatePublished - Nov 1989

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Sodium
Calcium
Membranes
Seals
Sarcolemma
Myofibrils
Hydrocarbons
Cobalt
Muscle Cells
Electrodes
Current density
Chemical activation
3',4'-dichlorobenzamil

Keywords

  • cardiac myocytes
  • Patch clamp
  • sodium current
  • sodium-calcium exchange current

ASJC Scopus subject areas

  • Physiology

Cite this

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