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

Abstract

Venous distension was associated with a depolarization in 31 % of cells tested.The depolarization averaged 2-8 mV and in 89 % of these was associated with an increase in membrane resistance. 5. A further 14 % of cells exhibited an increase in membrane resistance in the absence of depolarization.6. Venous distension increased the amplitude of fast e.p.s.p.s generated by stimulation of the lumbar splanchnic nerve or the intermesenteric nerve in 38 % of cells tested. 7. The results of this study demonstrate the existence of a mechanosensory pathway from the venous bed of the distal mesenteric region to the i.m.g. of the guinea-pig and suggest that distension may enhance neural transmission by increasing the excitability of ganglionic cells.

Disordered central cardiovascular regulation in portal hypertensive and cirrhotic rats

“…In view of the present results and our previous studies with capsaicin, we believe that a more likely mechanism is via mesenteric venous congestion or distention, which is known to stimulate visceral afferent nervous activity (25). The increased afferent signals would then be processed and integrated in the NTS and VLM, and spinal efferent signals would induce vasoactive changes.…”

Characteristics of synaptic input to three classes of sympathetic neurone in the coeliac ganglion of the guinea‐pig.

“…10). Such responses have been described by others, particularly in the IMG where they can be evoked by colonic (Kreulen & Peters 1986), venous (Keef & Kreulen, 1986) or ureteric (Amann, Dray & Hankins, 1988) distension. We found slow responses small and difficult to elicit in coeliac neurones, although readily evoked and larger in five of six IMG neurones we tested (unpublished observations).…”

“…The importance of these small variable responses in coeliac neurones seems questionable because of the unphysiological voltages required to stimulate the axons from which they are derived. However, it has apparently proved relatively easy to evoke such responses in the IMG by natural stimuli (Keef & Kreulen, 1986;Kreulen & Peters, 1986;Amann et al 1988). Clearly an increase in cell resistance during the slow potential would potentiate the effectiveness of subthreshold ESPs in initiating action potentials (see Dun & Ma, 1984).…”

Blockage of the afferent sensitive pathway prevents sympathetic atrophy and hemodynamic alterations in rat portal hypertension

“…These data suggested that a local splanchnic adrenergic inhibition, in a context of generalized adrenergic over activity, might contribute to arterial splanchnic vasodilation.The neural pathway controlling the cardiovascular system includes the primary afferent innervation (sensory neurons), the brain cardiovascular-regulatory nuclei and the effector arm composed by sympathetic and parasympathetic efferent nerves (6, 7). The afferent stimulus originated from pressure increases during portal hypertension in portal or mesenteric vessels (8,9) should reach the central nuclei through the afferent nerves, and from there, an efferent response might Liver International (2012)…”

“…The neural pathway controlling the cardiovascular system includes the primary afferent innervation (sensory neurons), the brain cardiovascular‐regulatory nuclei and the effector arm composed by sympathetic and parasympathetic efferent nerves . The afferent stimulus originated from pressure increases during portal hypertension in portal or mesenteric vessels should reach the central nuclei through the afferent nerves, and from there, an efferent response might connect to sympathetic ganglia. The signal responsible for the post‐ganglionic sympathetic nerve regression suggested by our studies could come from preganglionic neurons with a synaptic connection to post‐ganglionic neurons.…”