Coupled gating between individual cardiac ryanodine calcium release channels.
In order to study interactions between ryanodine receptor calcium release (RyR2) channels during excitation-contraction coupling in cardiac muscle, we used bilayer lipid membrane (BLM) and improved the method of cardiac sarcoplasmic vesicle fusion into BLM. We increased fusion gradient for the vesicles, used chloride ions for fusion up to concentration of 1.2 mol/l and fused the vesicles by adding them directly to the forming BLM. Under these conditions, increased probability of fusion of vesicles containing 2-7 ryanodine channels into BLM was observed. Interestingly about 10% of the channels did not gate into BLM independently, but their gating was coupled. At 53 mmol/l calcium solution, two coupled gating channels had double conductance (191 +/- 15 pS) in comparison with the noncoupled channels (93 +/- 10 pS). Activities of the coupled channels were decreased by 5 micromol/l ryanodine and inhibited by 10 micromol/l ruthenium red similarly as single RyR2 channels. We suppose that cardiac sarcoplasmic vesicles contain single as well as coupled RyR2 channels.
Ondrias
K
K
Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava. umfgonds@kramare.savba.sk
Mojzisová
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004553:Electric Conductivity; D004558:Electric Stimulation; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000502:physiology*; D008051:Lipid Bilayers / Q000378:metabolism*; D008564:Membrane Potentials / Q000502:physiology; D008567:Membranes, Artificial; D009206:Myocardium / Q000378:metabolism; D051381:Rats; D012433:Ryanodine / Q000378:metabolism* / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects / Q000502:physiology*; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000502:physiology*; D012680:Sensitivity and Specificity
D008051:Lipid Bilayers; D008567:Membranes, Artificial; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine; D002118:Calcium