Changes in contractility and calcium binding of guinea pig taenia coli by treatment with enzymes which hydrolyze sialic acid.
The effects of neuraminidase and phospholipase C on the contractility and the Ca++ -binding of guinea pig taenia coli were investigated. Potassium contracture or histamine-induced contracture of taenia coli was inhibited by treatment with neuraminidase, though acetylcholine-induced contracture was not. Treatment with phospholipase C markedly inhibited the contracture induced by isotonic potassium, histamine or acetylcholine. By treatment with neuraminidase for 4 hr, about 40 mumol/100 mg wer wt of sialic acid was released from taenia coli. This corresponded to two-fifths of total content of sialic acid. By treatment with phospholipase C for 2 hr, a similar amount of sialic acid to that produced  by neuraminidase treatment was released. The Scarchard plot of Ca++-binding was a biphasic pattern indicating the presence of two types ofthe Ca++ -binding site with different affinity constants. Neuraminidase produced a 57% decrease in the amount of bound Ca++. The Scatchard plot of Ca++ -binding changed to a monophasic pattern indicating the disapperance of thel ow affinity Ca++ -binding site. Phospholipase C caused a 59% decrease of bound Ca++. The Scatchard plot also indicated the disappearance of the low affinity Ca++ -binding site. From these results, we speculated that sialicacid residue of surface membrane of the muscle cell was first site in the Ca++ -influx mechanism.
D000109:Acetylcholine / Q000037:antagonists & inhibitors; D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D003106:Colon / Q000187:drug effects; D005260:Female; D006168:Guinea Pigs; D006634:Histamine H1 Antagonists; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000378:metabolism*; D009439:Neuraminidase / Q000494:pharmacology*; D010740:Phospholipases / Q000494:pharmacology*; D012794:Sialic Acids / Q000378:metabolism
D006634:Histamine H1 Antagonists; D012794:Sialic Acids; D010740:Phospholipases; D009439:Neuraminidase; D000109:Acetylcholine; D002118:Calcium