Inhibitory responses mediated by vagal nerve stimulation are diminished in stomachs of mice with reduced intramuscular interstitial cells of Cajal.
Intramuscular interstitial cells of Cajal (ICC-IM) are closely associated with enteric motor nerve terminals and electrically coupled to smooth muscle cells within the gastric musculature. Previous studies investigating the role of ICC-IM in motor neurotransmission have used indiscriminate electric field stimulation of neural elements within the gastric wall. To determine the role of ICC-IM in transduction of vagally-mediated motor input to gastric muscles electrical and mechanical responses to selective electrical vagal stimulation (EVS) were recorded from gastric fundus and antral regions of wild type and W/WVmice, which lack most ICC-IM. EVS evoked inhibitory junction potentials (IJPs) in wild type muscles that were attenuated or abolished by L-NNA. IJPs were rarely evoked in W/WVmuscles by EVS, and not affected by L-NNA. EVS evoked relaxation of wild type stomachs, but the predominant response of W/WVstomachs was contraction. EVS applied after pre-contraction with bethanechol caused relaxation of wild type gastric tissues and these were inhibited by the nitric oxide synthase inhibitor L-NNA. Relaxation responses were of smaller amplitude in W/WVmuscles and L-NNA did not attenuate relaxation responses in W/WVfundus muscles. These data suggest an important role for ICC-IM in vagally-mediated nitrergic relaxation in the proximal and distal stomach.
Discipline of Physiology, Adelaide Medical School, University of Adelaide, Adelaide, SA, 5005, Australia.
Elizabeth A H
EA
Beckett
Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA.
Kenton M
KM
Sanders
Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA.
Sean M
SM
Ward
D000818:Animals; D004558:Electric Stimulation; D018738:Hexamethonium / Q000494:pharmacology; D056885:Interstitial Cells of Cajal / Q000166:cytology*; D008810:Mice, Inbred C57BL; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000166:cytology*; D009469:Neuromuscular Junction / Q000187:drug effects / Q000502:physiology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D011978:Receptors, Nicotinic / Q000378:metabolism; D013270:Stomach / Q000294:innervation* / Q000502:physiology*; D055536:Vagus Nerve Stimulation
D018733:Nicotinic Antagonists; D011978:Receptors, Nicotinic; D018738:Hexamethonium; D019001:Nitric Oxide Synthase