Electrophysiology of neurones of the inferior mesenteric ganglion of the cat.

Abstract

SUMMARY1. Intracellular recordings were obtained from cells in vitro in the inferior mesenteric ganglia of the cat.2. Neurones could be classified into three types: non-spontaneous, irregular discharging and regular discharging neurones.3. Non-spontaneous neurones had a stable resting membrane potential and responded with action potentials to indirect preganglionic nerve stimulation and to intracellular injection of depolarizing current.4. Irregular discharging neurones were characterized by a discharge of excitatory post-synaptic potentials (e.p.s.p.s) which sometimes gave rise to action potentials. This activity was abolished by hexamethonium bromide, chlorisondamine and d-tubocurarine chloride. Tetrodotoxin and a low Ca2+-high Mg2+ solution also blocked on-going activity in irregular discharging neurones.5. Regular discharging neurones were characterized by a rhythmic discharge of action potentials. Each action potential was preceded by a gradual depolarization of the intracellularly recorded membrane potential. Intracellular injection of hyperpolarizing current abolished the regular discharge of action potential. No synaptic potentials were observed during hyperpolarization of the membrane potential.6. Nicotinic, muscarinic and adrenergic receptor blocking drugs did not modify the discharge of action potentials in regular discharging neurones. A low Ca2+-high Mg2+ solution also had no effect on the regular discharge of action potentials.7. Interpolation of an action potential between spontaneous action potentials in regular discharging neurones reset the rhythm of discharge.8. It is suggested that regular discharging neurones were endogenously active and that these neurones provided synaptic input to irregular discharging neurones.

Venous mechanoreceptor input to neurones in the inferior mesenteric ganglion of the guinea‐pig.

“…This is opposed to the conclusions of Jule & Szurszewski (1983) (Crowcroft et al 1971;Szurszewski & Weems, 1976). In contrast, venous distension changed the frequency of continuous activity in only 23 % of neurones exhibiting continuous activity.…”

Different types of ganglion cell in the cardiac plexus of guinea‐pigs.

“…In a proportion of P cells a rhythmical discharge of action potentials was detected. Similar discharges of action potentials, which are abolished by membrane hyperpolarization, have been recorded from cells in rat cardiac ganglia (Selyanko, 1992) and from cells of the cat inferior mesenteric ganglion (Jule & Szurszewski, 1983). The most likely explanation for this behaviour in P cells is that spontaneous activity results from the presence of hyperpolarization-activated cation-selective channels.…”

Potassium currents in rat prevertebral and paravertebral sympathetic neurones: control of firing properties.

“…These ganglia act as relatively sophisticated integrative centres controlling sympathetic outflow to the vasculature and enteric nervous system of the gastrointestinal tract (Szurszewski, 1981;Simmons, 1985) and can directly mediate some gastrointestinal reflexes even when isolated from central sympathetic input (Kuntz & Saccomanno, 1944;Semba, 1954). In contrast, most paravertebral ganglia transmit information from the spinal cord to the target organ without integrating other sources of information, although there is considerable convergence of preganglionic inputs (Skok, 1973 (Weems & Szurszewski, 1978;Griffith, Gallagher & Shinnick-Gallagher, 1980;Decktor & Weems, 1981Jule & Szurszewski, 1983; King & Szurszewski, 1984& Szurszewski, , 1988Cassell, Clark & McLachlan, 1986). Neurones in paravertebral ganglia, at least in the superior cervical ganglia and caudal lumbar ganglia, are almost exclusively 3352 319 phasic, whereas those in the prevertebral ganglia are a mixture of phasic and tonic (Weems & Szurszewski, 1978;Galvan & Sedlmeir, 1984;).…”