DIDS modifies the conductance, gating, and inactivation mechanisms of the cardiac ryanodine receptor.
The effects of the covalent modifier of amino groups, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) on the single-channel properties of purified sheep cardiac ryanodine receptors (RyR) incorporated into planar phospholipid bilayers were investigated. DIDS increased single-channel conductance and open probability (P(o)) and induced unique modifications to the voltage-dependence of gating. The effects of DIDS on conduction and gating were irreversible within the time scale of the experiments, and both effects were dependent on the permeant ion. DIDS induced a greater increase in conductance with Ca(2+) (20%) compared with K(+) (8%) as the permeant ion. After modification by DIDS, all channels could be rapidly inactivated in a voltage-dependent manner. The open probability of the DIDS-modified channel decreased with increasing positive or negative transmembrane potentials; however, inactivation was only observed at negative potentials. Our results demonstrate that inactivation of RyR channels is dependent on the ligand activating the channel, and this will have consequences for the control and termination of sarcoplasmic reticulum Ca(2+) release in cardiac cells.
Hill
Adam Parker
AP
Imperial College of Science, Technology and Medicine, London SW3 6LY, United Kingdom.
Sitsapesan
Rebecca
R
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology*; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D002118:Calcium / Q000378:metabolism; D004553:Electric Conductivity; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects; D007700:Kinetics; D008024:Ligands; D008564:Membrane Potentials; D008954:Models, Biological; D009206:Myocardium / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects* / Q000378:metabolism*; D012756:Sheep
D008024:Ligands; D019837:Ryanodine Receptor Calcium Release Channel; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium; D002118:Calcium