Fatty acid modifies Ca2+-dependent potassium channel activity in smooth muscle cells from the human aorta.
By using the patch-clamp technique the effect of 2-decenoic acid (DA) on Ca2+-activated potassium (K+) channels in the membrane of smooth muscle cells from the human aorta was studied. In the presence of 0.5 microM Ca2+ and 2 mM Mg2+ on the cytoplasmic side of the membrane, a more than tenfold elevation in the probability of the channels being open (po) was observed under the effect of DA. With divalent cation concentrations of less than 1 nM DA caused a more than twofold elevation in po. In the DA-treated membranes Mg2+ ions, which normally fail to activate the channels, brought about a nearly threefold increase in the channel activity when applied to the inner membrane surface. Channel sensitivity to the activating effect of cytoplasmic Ca2+ ions did not increase with the application of DA. Single-channel conductance was unchanged by DA exposure. We suggest that DA alters the Ca2+-binding mechanism of the channel, increasing its sensitivity to Mg2+ ions, presumably owing to membrane fluidization.
Bregestovski
P D
PD
Institute of Experimental Cardiology, Academy of Medical Sciences, Moscow, U.S.S.R.
Bolotina
V M
VM
Serebryakov
V N
VN
D001011:Aorta / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology* / Q000502:physiology; D003593:Cytoplasm / Q000502:physiology; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*
D005229:Fatty Acids, Monounsaturated; D015221:Potassium Channels; C052476:2-decenoic acid; D008274:Magnesium; D002118:Calcium