Journal of Neurophysiology, Vol 72, Issue 6 3023-3025, Copyright © 1994 by APS
Calcium-modulated inward rectification of a calcium-activated potassium channel in neurons
J. Kang, C. Sumners and P. Posner
Department of Physiology, University of Florida, College of Medicine, Gainesville 32610.
1. Inward rectification of a calcium-activated K+ channel in neurons
cultured from the hypothalamus and brain stem of 1-day-old rats was studied
by using patch-clamp techniques. A big conductance calcium-activated K+
channel with a slow gating rate was observed in inside-out patches. With
symmetrical K+ across patches, inward conductance of this calcium-activated
K+ channel was 216 +/- 14 (SE) pS (n = 4 patches), which changed little as
different [Ca2+] was included in the bath solution. Outward conductance of
this calcium-activated K+ channel was regulated by [Ca2+] in the bath
solution and was 74 +/- 15 pS with 500 microM Ca2+. The higher level of
Ca2+ on the intracellular side of the membrane caused the larger degree of
rectification. Mg2+ only had a minor effect on rectification of this
calcium-activated K+ channel.
