Electro-mechanical coupling in the complex stomach smooth muscles.
In the majority of experiments the ruminal preparations did not exhibit spontaneous electrical and contractile activity but showed a Ca-dependent spike-free myogenic tone. Ba2+ or Sr2+ evoked spike activity and phasic contractions and increased the muscle tonic tension. Tetraethylammonium (TEA) exerted no effect on the ruminal preparations but potentiated the effect of Ba2+. Acetylcholine (ACh) induced dose-dependent spike-free tonic contractions which were verapamil resistant and were suppressed by sodium nitroprusside. When applied to BaCl2- or TEA-pretreated preparations ACh caused spike activity and phasic contractions. The antral abomasum exhibited a spontaneous electrical activity--slow waves on which spike potentials were superimposed. ACh and TEA induced membrane depolarization and increased the spike activity and the phasic contraction amplitude.
D000018:Abomasum / Q000502:physiology; D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000037:antagonists & inhibitors / Q000502:physiology; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D012417:Rumen / Q000502:physiology; D012756:Sheep; D013279:Stomach, Ruminant / Q000187:drug effects / Q000502:physiology*
D000109:Acetylcholine; D002118:Calcium