Coming full circle: membrane potential, sarcolemmal calcium influx and excitation-contraction coupling in heart muscle.
In heart muscle, strong evidence shows that excitation-contraction coupling involves Ca-induced Ca-release. However, under some conditions, single heart cells show Ca release and contraction which is not correlated with Ca entry via the Ca channel, suggesting a second Ca-independent release mechanism. Similar observations were made in early, pioneering studies using voltage-clamped multi-cellular preparations. We review the influence that experimental preparations and conditions have had on excitation-contraction coupling theory over the last 20 years.
Hobai
I A
IA
Bristol Heart Institute, Department of Physiology, School of Medical Sciences, University of Bristol, UK. ionhobai@welchlink.welch.jhu.edu
Levi
A J
AJ
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000378:metabolism; D002478:Cells, Cultured; D004558:Electric Stimulation; D006168:Guinea Pigs; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011817:Rabbits; D051381:Rats; D012107:Research Design; D012508:Sarcolemma / Q000378:metabolism*
D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D002104:Cadmium; D002118:Calcium