A Smooth Muscle Excitatory Material from the Nerve of Remak of the Chicken Rectum

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The chicken rectum receives a powerful excitatory innervation of non-adrenergic, non-cholinergic (NANC) nerves via the Remak nerve which is a ganglionated nerve trunk in the fowl vicera. To extract a smooth muscle excitatory material from the Remak nerve, tissue samples were boiled in 0.01 N HCI at 100°C for 5-7 min, homogenized, and centrifuged. Aliquots of supernatant were defatted with petroleum ether and lyophilized. The lyophilized residue dissolved in water (ERN) was bioassayed for contracting activity on the longitudinal muscle of the guinea-pig ileum and, if needed, the isolated whole chick rectum. Approximately half of the contacting activity of ERN was attributable to acetylcholine. The remainder was found to be mediated by neither histamine, serotonin, angiotensin II nor prostaglandins (E1, E2 and F2α). The ERN activity was abolished by 2-3 min boiling in alkali and 30 min incubation at 37°C with pepsin, but sustained after boiling in acid, indicating that the mediator of the contracting activity is probably a peptide. Active fractions were obtained with one peak after gel filtration with Sephadex G-50. They were pooled and applied to a Sephadex G-25 column. The Ve/Vo values for the active material ranged from 1.69 to 1.85, indicating that it has a molecular weight of 1000-1300 by comparison with Ve/Vo, values for peptides of known molecular weights applied to the same column.