Effects of calcitonin gene-related peptide on the non-adrenergic inhibitory potentials in the intestinal smooth muscle cells of the guinea pig.
Effects of calcitonin gene-related peptide (CGRP) on the spontaneous and evoked contractions in the duodenal and ileal preparations, the spontaneous action potentials and the non-adrenergic non-cholinergic inhibitory potentials (NANC i.p.s) in the longitudinal smooth muscle cells of the guinea-pig duodenum and ileum were examined. Preparations were pretreated with atropine (1 microM) and guanethidine (5 microM). CGRP (26 nM) was found to inhibit spontaneous and evoked contractions. The resting membrane potential of the longitudinal smooth muscle was not altered but the frequency of spontaneous action potentials was decreased by the treatment with CGRP (6-104 nM). Field stimulation evoked the NANC i.p.s and the pretreatment with atropine (1 microM) and guanethidine (5 microM) caused an increase in the amplitude of the NANC i.p.s in the longitudinal smooth muscle. However, CGRP (6-104 nM) did not change the amplitude of the NANC i.p.s. The rebound excitation in the longitudinal muscle membrane was inhibited by CGRP. The single spike activity of the myenteric neurons in the duodenum was not affected by CGRP (26-104 nM). The results suggest that CGRP inhibits the intestinal motility by non-neurogenic NANC manner and does not activate the NANC inhibitory neurons in intestine.
Ohkawa
H
H
Department of Physiology, Yamaguchi University School of Medicine, Ube, Japan.
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology*; D004386:Duodenum / Q000187:drug effects; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009197:Myenteric Plexus / Q000187:drug effects
D015740:Calcitonin Gene-Related Peptide