AJP - Gastrointestinal and Liver Physiology, Vol 255, Issue 2 184-G190, Copyright © 1988 by American Physiological Society

ARTICLES

Synaptic behavior of myenteric neurons in guinea pig distal colon

P. R. Wade and J. D. Wood
Department of Physiology, College of Medicine, Ohio State University, Columbus 43210.

Intracellular recording methods were used in vitro to analyze the synaptic behavior of neurons in myenteric ganglia of guinea pig distal colon. Fast excitatory postsynaptic potentials (EPSPs) were observed in a variety of types of colonic neurons. Both spontaneous and stimulus-evoked EPSPs were abolished or suppressed by addition of hexamethonium, tetrodotoxin, or elevation of Mg2+ and reduction of Ca2+ in the bathing medium. Individual neurons usually received inputs from several fiber tracts and multiple EPSPs were sometimes evoked by electrical stimulation of single-fiber tracts. Stimulus-evoked fast EPSPs were always of greater amplitude, longer duration, and longer decay time than were spontaneous fast EPSPs in the same neurons. No rundown of the fast EPSPs occurred during prolonged stimulation at frequencies up to 10 Hz. Repetitive stimulation evoked slow depolarizing potentials (slow EPSPs) in 25% of the neurons. Characteristics of the slow EPSPs were 1) slow rise times, 2) duration in the seconds time domain, 3) enhanced excitability, 4) increased input resistance, and 5) reduction of hyperpolarizing after-potentials. In general, the variety of synaptic potentials and the properties of the events were the same as found in myenteric neurons of the guinea pig small bowel. Compared with synaptic behavior of small intestinal myenteric neurons, the notable differences were absence of the rundown phenomenon for fast EPSPs in the colonic neurons and a greater incidence of spontaneously occurring fast EPSPs.

This article has been cited by other articles:

				E. M. Krauter, D. R. Linden, K. A. Sharkey, and G. M. Mawe Synaptic plasticity in myenteric neurons of the guinea-pig distal colon: presynaptic mechanisms of inflammation-induced synaptic facilitation J. Physiol., June 1, 2007; 581(2): 787 - 800. [Abstract] [Full Text] [PDF]

				S. K. Sarna Neuronal locus and cellular signaling for stimulation of ileal giant migrating and phasic contractions Am J Physiol Gastrointest Liver Physiol, May 1, 2003; 284(5): G789 - G797. [Abstract] [Full Text] [PDF]

				S. H. Kang, P. Vanden Berghe, and T. K. Smith Ca2+-activated Cl- current in cultured myenteric neurons from murine proximal colon Am J Physiol Cell Physiol, April 1, 2003; 284(4): C839 - C847. [Abstract] [Full Text] [PDF]