The Journal of Neurophysiology Vol. 83 No. 3 March 2000, pp. 1253-1263
Copyright ©2000 by the American Physiological Society
Diverse Ionic Currents and Electrical Activity of Cultured
Myenteric Neurons From the Guinea Pig Proximal Colon
Fivos
Vogalis,
Kirk
Hillsley, and
Terence
K.
Smith
Department of Physiology and Cell Biology, University of Nevada
School of Medicine, Reno, Nevada 89557
Vogalis, Fivos,
Kirk Hillsley, and
Terence
K. Smith.
Diverse Ionic Currents and Electrical Activity of Cultured
Myenteric Neurons From the Guinea Pig Proximal Colon. J. Neurophysiol. 83: 1253-1263, 2000. The aim of this
study was to perform a patch-clamp analysis of myenteric neurons from
the guinea pig proximal colon. Neurons were enzymatically dispersed,
cultured for 2-7 days, and recorded from using whole cell patch clamp.
The majority of cells fired phasically, whereas about one-quarter of
the neurons fired in a tonic manner. Neurons were divided into three
types based on the currents activated. The majority of tonically firing
neurons lacked an A-type current, but generated a large fast transient outward current that was associated with the rapid repolarizing phase
of an action potential. The fast transient outward current was
dependent on calcium entry and was blocked by tetraethylammonium. Cells
that expressed both an A-type current and a fast transient outward
current were mostly phasic. Depolarization of these cells to
suprathreshold potentials from less than 
60 mV failed to trigger action potentials, or action potentials were only triggered after a
delay of >50 ms. However, depolarizations from more positive potentials triggered action potentials with minimal latency. Neurons that expressed neither the A-type current or the fast transient outward
current were all phasic. Sixteen percent of neurons were similar to
AH/type II neurons in that they generated a prolonged afterhyperpolarization following an action potential. The current underlying the prolonged afterhyperpolarization showed weak inward rectification and had a reversal potential near the potassium equilibrium potential. Thus cultured isolated myenteric neurons of the
guinea pig proximal colon retain many of the diverse properties of
intact neurons. This preparation is suitable for further biophysical and molecular characterization of channels expressed in colonic myenteric neurons.
