<i>IN VITRO</i> SPONTANEOUS MOTILITY OF GASTRIC SMOOTH MUSCLES OF THE SHEEP

Wong, May; McLeay, L. M.

doi:10.1113/expphysiol.1988.sp003172

Cited by 16 publications

(13 citation statements)

References 19 publications

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“…Hexamethonium and atropine may have little or no effect on the spontaneous activity in vitro of isolated muscle strips prepared from the abomasal antrum and the acetylcholine-evoked contraction is atropine-sensitive (Wong and McLeay, 1988). Although the concentrations used in Wong and McLeay's (1988) study are not directly comparable with the present in vivo study, the acetylcholine response was not apparently affected in the latter by cholinergic blocking drugs.…”

Section: Action Of Drugscontrasting

confidence: 58%

Electrophysiological characteristics of tension receptors in the abomasal antrum of sheep

Cottrell

Reynolds

1994

Vet Res Commun

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Unitary impulse activity from tension receptors in the abomasal antrum in sheep anaesthetized with chloralose was studied with concurrent measurements of isometric tension in the antral wall, intraluminal pressures and electromyography (EMG). Rhythmical background activity had a close correlation with intraluminal pressure changes and usually a close correlation with local increases in EMG activity and isometric tension. Impulse frequencies increased, but were not sustained, following changes from isotonic to isometric conditions. Tension receptors were excited by transmural compression, by antral distension and by local intra-arterial injections of acetylcholine (2.5-25 micrograms), pentagastrin (10-20 micrograms), 5-hydroxytryptamine (1-20 micrograms), adrenaline (10 micrograms) cholecystokinin-8 (1-5 micrograms) or bradykinin (0.5-20 micrograms), and by systemic injections of bethanecol (5-1000 micrograms). Local intra-arterial perfusions of atropine (50 micrograms) and hexamethonium (100 micrograms) did not abolish spontaneous antral movements or affect the enhanced impulse activity evoked by acetylcholine or 5-hydroxytryptamine. Most antral tension receptors were excited by increases in antral tension or passive distension; they therefore functioned 'in series' with the muscularis externa. The discharges of three tension receptors were 'off-loaded' early during the contraction evoked by local injections of pentagastrin (10-20 micrograms).

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Section: Action Of Drugscontrasting

confidence: 58%

Electrophysiological characteristics of tension receptors in the abomasal antrum of sheep

Cottrell

Reynolds

1994

Vet Res Commun

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“…Neurones containing these transmitters are generally assumed to be involved in excitation of the gastrointestinal muscles (Brookes 2001a). In functional studies on isolated muscle strips of the forestomach, cholinergic and SPergic neurotransmission leading to contractile responses have been demonstrated (Vassileva et al 1978;Veenendaal et al 1982;Wong and McLeay 1988). It might therefore be concluded that the DiIlabelled ChAT/SP-positive neurones function as excitatory motor neurones to the muscle.…”

Section: Discussionmentioning

confidence: 95%

Ruminal muscle of sheep is innervated by non-polarized pathways of cholinergic and nitrergic myenteric neurones

Pfannkuche

Schemann

Gäbel

2002

Cell and Tissue Research

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The motility patterns of the reticulorumen evoke mainly mixing of the ingesta. So far unknown, intrinsic neural circuits of the enteric nervous system are involved in the control of these motility patterns. The aim of the study was to characterize neurochemically sheep ruminal myenteric neurones, in particular the neural pathways innervating the ruminal muscle layers. Cell bodies within the myenteric plexus projecting to the longitudinal or circular muscle layer were retrogradely labelled by direct application of the fluorescent tracer 1,1'-didodecyl-3,3,3',3'-tetramethyl indocarbocyanine perchlorate (DiI) onto the circular or longitudinal muscle. The neurochemical code of myenteric neurones was identified by their immunoreactivity for choline acetyltransferase (ChAT), nitric oxide synthase (NOS), substance P (SP) and vasoactive intestinal peptide (VIP). According to their neurochemical code, ruminal myenteric neurones were divided into three populations: ChAT/SP (68% of all myenteric neurones), NOS/VIP (26% of all myenteric neurones) and ChAT/- (5% of all myenteric neurones). Application of DiI onto the circular or longitudinal muscle revealed on average 64 or 44 labelled cell bodies in the myenteric plexus, respectively. DiI-labelled neurones expressed the code ChAT/SP or NOS/VIP. In the pathways to circular or longitudinal muscle, ChAT/SP-positive neurones outnumbered NOS/VIP-immunoreactive neurones by 5:1 and 2:1. Pathways to the circular or longitudinal muscle did not exhibit any pronounced polarized innervation patterns. This study demonstrated specific projections of myenteric neurones to the ruminal muscle. Neurones expressing the code ChAT/SP might function as excitatory muscle motor neurones, whereas NOS/VIP neurones are likely to act as inhibitory muscle motor neurones.

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“…The excitatory effect of SP is also hypothesized by Pfannkuche et al. (2003), who found extensive co‐localization of SP and acetylcholine in the RG of sheep and whose contractile effects on the reticulum have been reported by Wong & McLeay (1988). The prevalent distribution of this neuropeptide in the lips and in the lip–floor junction supports the great importance of excitatory stimuli to contract the lips and form the tube for milk transport following vagal stimulation.…”

Section: Discussionmentioning

confidence: 54%

“…In fact, analogously to what has been observed in the GITs of many other mammals, it is plausible to hypothesize that SP has an excitatory role (Brookes, 2001); furthermore, both acetylcholine and SP evoke contractions of the isolated ruminal smooth muscle (Vassileva et al 1978;Veenendaal et al 1982). The excitatory effect of SP is also hypothesized by Pfannkuche et al (2003), who found extensive co-localization of SP and acetylcholine in the RG of sheep and whose contractile effects on the reticulum have been reported by Wong & McLeay (1988). The prevalent distribution of this neuropeptide in the lips and in the lip-floor junction supports the great importance of excitatory stimuli to contract the lips and form the tube for milk transport following vagal stimulation.…”

Section: Discussionmentioning

confidence: 62%

An immunohistochemical study of the distribution of nitric oxide synthase-immunoreactive neurons and fibers in the reticular groove of suckling lambs

Lalatta-Costerbosa¹,

Clavenzani²,

Petrosino³

et al. 2011

Journal of Anatomy

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The reticular groove (RG) is a specialized region of ruminant forestomach which, in suckling animals, via a vagovagal reflex, transforms itself into a tube to ensure the direct transport of milk from the esophagus to the abomasum. The nervous mechanism controlling the RG movement is not fully understood; however, at this level, the enteric nervous system (ENS) shows the highest neuronal density when compared with other forestomach compartments. Because nitric oxide is considered the putative major mediator of non-adrenergic noncholinergic smooth muscle relaxation, the aim of the present study was to investigate the ENS of the RG of suckling lambs, both in the floor and in the lip, with particular regard to nitric oxide synthase (NOS)-immunoreactivity (-IR), by means of double immunohistochemical staining. NOS antiserum was used in association with some neurochemical markers which have been utilized by many authors in ENS. A rich innervation of fibers extended along the entire length of the RG. Proceeding distally, the number of neurons stained with a panneuronal marker increased; they were more numerous in the lips and lip-floor junction than in the floor itself. However, the percentage of NOS-IR neurons was the same in the proximal and distal parts. Many NOS-IR neurons often co-expressed galanin and dopamine b-hydroxylase. Neurochemical markers, such as calbindin, calcitonin gene-related peptide, IB4 and neurofilament 200 kDa, usually used to identify primary sensory neurons were not expressed in RG neurons, and the co-localization of NOS with tyrosine hydroxylase and substance P was rarely found. When compared with other districts, the RG showed some peculiar aspects, such as the lack of both neurons in the submucosal plexus and the lack of typical sensory neurons.

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IN VITRO SPONTANEOUS MOTILITY OF GASTRIC SMOOTH MUSCLES OF THE SHEEP

Cited by 16 publications

References 19 publications

Electrophysiological characteristics of tension receptors in the abomasal antrum of sheep

Electrophysiological characteristics of tension receptors in the abomasal antrum of sheep

Ruminal muscle of sheep is innervated by non-polarized pathways of cholinergic and nitrergic myenteric neurones

An immunohistochemical study of the distribution of nitric oxide synthase-immunoreactive neurons and fibers in the reticular groove of suckling lambs

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