Gap junctions in gastrointestinal muscle contain multiple connexins.
In the canine gastrointestinal tract, the roles that gap junctions play in pacemaking and neurotransmission are unclear. Using antibodies to connexin (Cx)43, Cx45, and Cx40, we determined the distribution of these connexins. Cx43 was present in all locations where structural gap junctions occur. Cx40 was also widely distributed in the circular muscle of the lower esophageal sphincter (LES), stomach, and ileum. Cx45 was sparsely distributed in circular muscle of the LES. In the interstitial cells of Cajal (ICC) networks of myenteric plexus, in the deep muscular and submuscular plexuses, sparse Cx45 and Cx40 immunoreactivity was present. In colon, immunoreactivity was found only in the myenteric and submuscular plexus and nearby circular muscle cells. No immunoreactivity was found in sites lacking structural gap junctions (longitudinal muscle, inner circular muscle of the intestine, and most circular muscle of the colon). Studies of colocalization of connexins suggested that in the ICC networks, some colocalization of Cx43 with Cx40 and/or Cx45 occurred. Thus gap junctions in canine intestine may be heterotypic or heteromeric and have different conductance properties in different regions based on different connexin compositions.
Wang
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Department of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada.
Daniel
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D000818:Animals; D003106:Colon / Q000737:chemistry; D018031:Connexin 43 / Q000032:analysis / Q000276:immunology; D017630:Connexins / Q000032:analysis* / Q000276:immunology; D004064:Digestive System / Q000737:chemistry*; D004285:Dogs; D004943:Esophagogastric Junction / Q000737:chemistry; D005260:Female; D017629:Gap Junctions / Q000737:chemistry*; D007082:Ileum / Q000737:chemistry; D007150:Immunohistochemistry; D008297:Male; D009130:Muscle, Smooth / Q000737:chemistry*; D013270:Stomach / Q000737:chemistry; D000097003:Gap Junction alpha-5 Protein
D018031:Connexin 43; D017630:Connexins; D000097003:Gap Junction alpha-5 Protein; C082920:connexin 45