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Single cardiac sarcoplasmic reticulum Ca2+-release channel: activation by caffeine.

The American journal of physiology (1989-02-01)
E Rousseau, G Meissner
ABSTRACT

Caffeine is thought to affect excitation-contraction coupling in cardiac muscle by activating the sarcoplasmic reticulum (SR) Ca2+-release channel. The effect of caffeine at the single channel level was studied by incorporating canine cardiac SR vesicles into planar lipid bilayers. Cardiac Ca2+-release channels were activated in a steady-state manner by millimolar cis-caffeine and displayed a unitary conductance (77 pS in 50 mM Ca2+ trans) similar to that previously observed for the Ca2+-activated cardiac channel. The caffeine-activated channel was moderately sensitive to the voltage applied across the bilayer, was sensitive to further activation by ATP, and was inhibited by Mg2+ and ruthenium red. Kinetic analysis showed that at low Ca2+ concentration, caffeine activated the channel by increasing the frequency and the duration of open events.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Caffeine, anhydrous, tested according to Ph. Eur.