Role of alpha adrenoceptors in opossum internal anal sphincter.

Yamato, Shigeru; Rattan, Satish

doi:10.1172/jci114728

Cited by 44 publications

(36 citation statements)

References 17 publications

(15 reference statements)

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“…Consistent with this, rectal balloon distension-mediated IAS relaxation is significantly suppressed by the ␣ 2 -adrenoceptor agonist clonidine (28) and by lumbar sympathetic nerve stimulation (14) in the opossum. Although HGN stimulation suppressed the rectal balloon distension-induced fall in IAS pressure, rectal balloon distension caused a fall in IAS pressure without any significant change in HGN efferent activity (20).…”

Section: Discussionsupporting

confidence: 69%

Integrative control of rectoanal reflex in guinea pigs through lumbar colonic nerves

Yamanouchi¹,

Shimatani²,

Kadowaki

et al. 2002

American Journal of Physiology-Gastrointestinal and Liver Physi

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The aim of the present study was to analyze the neuromodulation of rectoanal reflex activity by lumbar sympathetic nerves in guinea pigs. The mechanical activities of the rectum were recorded with a balloon connected to a pressure transducer, and those of the internal anal sphincter (IAS) were recorded with a custom-made strain gauge force transducer. Gradual and sustained rectal distension evoked the rectoanal reflex, causing cholinergic contractions of the rectum and synchronous nitrergic relaxations of the IAS. Section of the lumbar colonic nerves enhanced both rectal contractions and IAS relaxations. Section of the 13th thoracic cord abolished both rectal contractions and IAS relaxations, but section of the lumbar colonic nerves restored them. Lumbar sympathectomy and pithing sacral cords greatly diminished these rectal contractions and IAS relaxations, but the intrinsic reflex component remained. N G -nitro-L-arginine methyl ester enhanced the intrinsic reflex-mediated contraction of the rectum and abolished reflex-mediated relaxation of the IAS and converted into cholinergic contractions. The present results indicate that the extrinsic lumbar inhibitory outflow causes marked inhibition of the rectoanal reflex via the lumbar colonic nerves. extrinsic reflex; internal anal sphincter; intrinsic reflex; pelvic nerves; rectum WE HAVE PREVIOUSLY REPORTED (22) that a rectorectal reflex is induced by prompt rectal distension in the guinea pig. This rectorectal reflex is composed of the extrinsic excitatory reflex via sacral cords (S1-3), the extrinsic inhibitory reflex via lumbar cords (L1-4), and the intrinsic cholinergic excitatory reflex via the enteric nervous system (22). The afferent and efferent limbs of the extrinsic excitatory reflex travel in the pelvic nerves, whereas the limbs of the extrinsic inhibitory reflex pass in the lumbar colonic nerves (LCNs) (22). Furthermore, we have found that the inhibitory reflex is suppressed by descending input from the pontine defecation center, leading to a disinhibition of the sacral excitatory reflex and intrinsic excitatory reflex (22)(23)(24). In view of these findings, we have proposed that the lumbar colonic inhibitory reflex contributes to the rectorectal reflex, one important component of the defecation reflex (22-25).To clarify the integrative control of the defecation reflex by the lumbar sympathetic nerves, the goal of the present study was to elucidate the rectoanal reflex [especially the rectointernal anal sphincter (recto-IAS) reflex], because the act of defecation is a consequence of successive phenomena occurring in both the colon and anorectum (9). There is considerable evidence to support the view that the descending inhibitory reflex involving inhibitory motor neurons occurs along the entire large intestine (1, 2, 6, 7). In the current study, the rectoanal reflex (especially the recto-IAS reflex) was analyzed, and the role of the lumbar sympathetic nerves in integrative control of the distension-induced rectoanal reflex was evaluated. METHODS AND MA...

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Section: Discussionsupporting

confidence: 69%

Integrative control of rectoanal reflex in guinea pigs through lumbar colonic nerves

Yamanouchi¹,

Shimatani²,

Kadowaki

et al. 2002

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…benign prostatic hypertrophy). They are effective smooth muscle relaxants and have been shown to reduce resting anal tone in opossums [167]. Pitt et al showed a statistically significant reduction in anal tone, by 35.8% in patients with anal fissures and by 39.9% in controls within an hour of oral administration of indoramin, an alpha-1 adrenoceptor antagonist (p<0.05) [168].…”

Section: Alpha-1 Adrenoceptor Blockersmentioning

confidence: 99%

A review of chronic anal fissure management

Collins

Lund

2007

Tech Coloproctol

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Anal fissure management has rapidly progressed in the last 15 years as our understanding of fissure pathophysiology has developed. All methods of treatment aim to reduce the anal sphincter spasm associated with chronic anal fissures. Surgical techniques have been used for over 100 years with success. Lateral internal sphincterotomy remains the surgical treatment of choice for many practitioners. Postoperative impairment of continence remains controversial. Recently, less invasive methods of treatment have been explored. Topical nitrates, calcium channel blockers and botulinum toxin are established treatments. These and other non-surgical treatments are described in this review. Various guidelines and treatment algorithms for anal fissure are also discussed.

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“…It has been shown that the enzymes responsible for the production of H 2 S are present in the enteric nerves and the myenteric ICCs, 23 both of which can be found in the IAS. 8,24 Inhibition of H 2 S synthesis with PAG + AOAA depressed relaxation responses to EFS and the depression was additive to that of ODQ and therefore independent of cGMP indicating a small role for H 2 S in relaxation of the IAS to EFS. In conclusion the neurogenic contraction of the porcine IAS can be attributed mainly to noradrenaline and ATP, with both neurotransmitters probably released from adrenergic nerves.…”

Section: Discussionmentioning

confidence: 99%

“…It is known that NO plays an important role as an inhibitory neurotransmitter in the IAS 6 and that noradrenaline acting via α 1 -adrenoceptors is responsible for contracting the sphincter. [7][8][9] Furthermore, the relative contribution of each neurotransmitter system to the responses of the IAS has not been established. The aim of the present study was to identify the neurotransmitters released during electrical field stimulation (EFS) of the porcine IAS and determine the relative contributions of each transmitter to the functional responses.…”

Section: Introductionmentioning

confidence: 99%

Three Gaseous Neurotransmitters, Nitric oxide, Carbon Monoxide, and Hydrogen Sulfide, Are Involved in the Neurogenic Relaxation Responses of the Porcine Internal Anal Sphincter

Folasire

Mills

Sellers

et al. 2015

J Neurogastroenterol Motil

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Background/AimsThe internal anal sphincter (IAS) plays an important role in maintaining continence and a number of neurotransmitters are known to regulate IAS tone. The aim of this study was to determine the relative importance of the neurotransmitters involved in the relaxant and contractile responses of the porcine IAS. MethodsResponses of isolated strips of IAS to electrical field stimulation (EFS) were obtained in the absence and presence of inhibitors of neurotransmitter systems. ResultsContractile responses of the sphincter to EFS were unaffected by the muscarinic receptor antagonist, atropine (1 mM), but were almost completely abolished by the adrenergic neuron blocker guanethidine (10 mM). Contractile responses were also reduced (by 45% at 5 Hz, P < 0.01) following desensitisation of purinergic receptors with α,β-methylene-ATP (10 mM). In the presence of guanethidine, atropine, and α,β-methylene-ATP, the remaining relaxatory responses to EFS were examined. These responses were not altered by the cyclooxygenase inhibitor, indomethacin (5 mM), the vasoactive intestinal polypeptide receptor antagonist, [D-p-Cl-Phe 6 ,Leu 17 ]-vasoactive intestinal peptide (PheLeu-VIP; 100 nM), or the purinoceptor antagonists, 8-phenyltheophyline (P1 receptors) or suramin (P2 receptors). However, relaxation responses were reduced by Nω-nitro-L-arginine (L-NNA; 100 mM), an inhibitor of nitric oxide synthesis (40-50% reduction), zinc protoprophyrin IX (10 mM), an inhibitor of carbon monoxide synthesis (20-40% reduction), and also propargylglycine (30 mM) and aminooxyacetic acid (30 mM), inhibitors of hydrogen sulphide synthesis (15-20% reduction). ConclusionsStimulation of IAS efferent nerves releases excitatory and inhibitory neurotransmitters: noradrenaline is the predominant contractile transmitter with a smaller component from ATP, whilst 3 gases mediate relaxation responses to EFS, with the combined contributions being nitric oxide > carbon monoxide > hydrogen sulfide.

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Role of alpha adrenoceptors in opossum internal anal sphincter.

Cited by 44 publications

References 17 publications

Integrative control of rectoanal reflex in guinea pigs through lumbar colonic nerves

Integrative control of rectoanal reflex in guinea pigs through lumbar colonic nerves

A review of chronic anal fissure management

Three Gaseous Neurotransmitters, Nitric oxide, Carbon Monoxide, and Hydrogen Sulfide, Are Involved in the Neurogenic Relaxation Responses of the Porcine Internal Anal Sphincter

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