Plants - Drugs Mind - Spirit Freedom - Law Arts - Culture Library  
Erowid References Database
Adenbanjo AO, Ambache N, Verney J. 
“The Inhibitory Transmission To The Internal Anal Sphincter”. 
Brit.J.Pharmacol.. 1976;56(3):392P-393P.
Inhibition of this sphincter by sacral nerves is atropine-resistant. Our results show that this sacral inhibitory post-ganglionic transmission resembles that present in the retractor penis. It is likely that the other atropine-resistant sacral inhibitory effects described by Langly and Anderson (1895b) are similarly mediated.

PROCEDURE: The anal canal is excised by a wide perineal incision. The anus is slit and a 1 - 2 cm width of mucosa, adjoining the skin, is dissectd off the undelying sphincters. A plane of separation is found between the pink-brown external sphincter (skeletal) and the white smooth muscle band of the internal sphincter. Strips from > 50 rabbit, pig, dog, cat and guinea-pig sphincters were suspended in Krebs-Henseleit (35░C) and stimulated transmurally (1-20) pulses at 1 min intervals; supramaximal voltage; 0.2 ms 10 Hz).

RESULTS: Transmural stimulation elicited repeateable inhibitions unaffectd by pentolinium (93 mcM) but abolished by tetrodotoxin (0.63 mcM). Pure relaxations were obtained without │rebound▓ in most preparations; only a few had an additonal (adrenergic) motor component which disappeared after guanethidine, 10 mcM, or phentolamine, 5.3 mcM. That acetylcholine is not the inhibitory parasympathetic transmitter was shown by : (a) its opposite, contractile effect, except once when, in high doses (277 mcM), acetylcholine, llike nicotine, produced a pentolinium-susceptivle inhibition. (b) Persistence of these neurogenic inhibitions in atropine (0.029-29 mcM); and (c) failure of physostigmine (7.7 mcM) to potentiate the atropine-resistant inhibitions. The inhibitory transmission is not adrenergic or tryptaminergic, persisting after propranolol (6.8 mcM) or butoxamine (6.6 mcM) +/- phentolamine (5.3 mcM) or phenoxybenzamine (5.8 mcM); and after guanethidine (10 mcM), bretylium (24 mcM) or LSD (125 nM). Transmission by ATP, histamine or prostoglandins (E and F), was excluded.
Comments and Responses to this Article
Submit Comment
[ Cite HTML ]