P. Sah et Js. Isaacson, CHANNELS UNDERLYING THE SLOW AFTERHYPERPOLARIZATION IN HIPPOCAMPAL PYRAMIDAL NEURONS - NEUROTRANSMITTERS MODULATE THE OPEN PROBABILITY, Neuron, 15(2), 1995, pp. 435-441
The slow afterhyperpolarization in hippocampal pyramidal neurons is me
diated by a calcium-activated potassium current (I-AHP) and is a targe
t for a variety of different neurotransmitters. The characteristics of
the channels underlying I-AHP and how they are modulated by neurotran
smitters are, however, unknown. In this study, we have examined the pr
operties of the channels underlying I-AHP using fluctuation analysis o
f the macroscopic current. Our results indicate that this channel has
a unitary conductance of 2-5 pS and a mean open time of about 2 ms. Wh
en the peak amplitude of I-AHP was maximal, these channels have an ope
n probability of 0.4. Noradrenaline and carbachol reduced I-AHP amplit
ude by lowering open channel probability. These results indicate that
a novel calcium-activated potassium channel underlies I-AHP. This chan
nel is modulated in a similar fashion by two different transmitter sys
tems that utilize distinct protein kinases.