Extraction and partial purification of spasmogenic substances in Auerbach's plexus.
A bland procedure, conducted in ice, is described for the extraction with HCl of smooth-muscle-contracting substances from plexus-containing ileal longitudinal muscle (l.m.) sheets obtained mainly from rabbits and some guinea-pigs. The spasmogenic activity in rabbit extracts was distinguished from acetylcholine, histamine and 5-hydroxytryptamine by antagonists; and from prostaglandins, by its insolubility in ether at acid pH and by pretreatment of the animals with indomethacin. The fact that it contracts the separated l.m. of the guinea-pig ileum, whether plexus-containing or plexus-free, and in atropine distinguishes it also from methionine-enkephalin, somatostatin, 13-norleucine motilin, bombesin, and cholecystokinin octapeptide (CCK8). This activity was partially purified, first by several partitions with ether at pH 1.4-2.2 and then by treatment at pH 4.5-5 with lead acetate. The virtual absence of ATP was confirmed by the firefly bioluminescence technique. The guinea-pig-ileum-contracting component in the partially purified extracts was destroyed by pepsin, chymotrypsin and DPCC-treated trypsin, indicating its peptide nature and distinguishing it from oxytocin, vasopressin, bradykinin, etc. In parallel assays the partially purified rabbit extracts were considerably more active than Substance P on jird or rat ascending colons than on the guinea-pig l.m., suggesting the presence of a second spasmogenic component in the extracts. In guinea-pig extracts the partially purified activity was 8-16 times greater when plexus-containing than when plexus-free, pointing to Auerbach's plexus as the source of the activity.
D000818:Animals; D001681:Biological Assay; D005849:Gerbillinae; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008722:Methods; D009119:Muscle Contraction / Q000187:drug effects; D009197:Myenteric Plexus / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D013035:Spasm / Q000139:chemically induced*; D013373:Substance P / Q000494:pharmacology; D014020:Tissue Extracts / Q000302:isolation & purification* / Q000494:pharmacology
D014020:Tissue Extracts; D013373:Substance P