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Activation and blocking effects of divalent cations on the calcium-dependent potassium channel of high conductance
V L Zamoyski1, V N Serebryakov, R Schubert
1Institute of Experimental Cardiology, USSR Cardiology Research Center, Moscow.
Abstract:
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.
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