Activation and blocking effects of divalent cations on the calcium-dependent potassium channel of high conductance.
Using the patch-clamp technique the action of internal barium- and magnesium-ions on the calcium-dependent potassium channel in the membrane of vascular smooth muscle cells from the media layer of the human aorta was studied. Under symmetrical potassium conditions in excised inside-out patches bathed in the standard solution containing EGTA, the addition of barium as well as magnesium led to a concentration-dependent shift of the activation-curves to negative values of the membrane potential compared with the control, a block of single channel activity by barium, whereas no inhibitory effects by magnesium were registered. Thus, these results suggest that the process of channel activation of the calcium-dependent potassium channel of high conductance depends not merely on calcium but also on other divalent earthalkali ions.
Institute of Experimental Cardiology, USSR Cardiology Research Center, Moscow.
V L
VL
Zamoyski
V N
VN
Serebryakov
R
R
Schubert
D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002413:Cations, Divalent / Q000494:pharmacology*; D002478:Cells, Cultured; D006801:Humans; D008274:Magnesium / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*
D002413:Cations, Divalent; D015221:Potassium Channels; D001464:Barium; D008274:Magnesium; D002118:Calcium