Ultrastructural localization of adrenergic nerve terminals in the circular muscle layer and muscularis mucosae of rat duodenum after acute treatment with 6-hydroxydopamine

Abstract

The ultrastructure of the intrinsic adrenergic innervation of the circular muscle coat and muscularis mucosae of rat duodenum was studied following acute treatment with 6-hydroxydopamine. Adrenergic terminals were found among intramuscular nerve bundles. They were most numerous in the outer layer of the circular coat, where close neuromuscular contacts were commonly encountered. Adrenergic terminals also innervated the inner layer of the circular coat and the muscularis mucosae, where only wide neuromuscular contacts were found. The evidence suggests that smooth muscle cells in the rat duodenum may be directlyinfluenced by adrenergic nerves.