title: Phasic and tonic types of smooth muscle activity in lower oesophageal sphincter and stomach of the dog.
abstract: Mechanical activity of isolated circular muscle strips from the lower oesophageal sphincter (LES), fundus, corpus and antrum of canine stomach was recorded. Nifedipine (10(-6) mol/l) selectively suppressed the phasic components of spontaneous, acetylcholine (ACh)- and noradrenaline (NA)-induced activity of gastric strips. The nifedipine-resistant tonic components of gastric strips were suppressed by nitroprusside sodium (NP) (10(-5) mol/l). LES strips exhibited only weak spontaneous activity. Their ACh-induced activation was nearly completely suppressed by nifedipine. Only NA was able to elicit a strong nifedipine-resistant activation which was, in contrast to the activation of fundus strips, not suppressed by NP.
mesh_terms: D000109:Acetylcholine; D000818:Animals; D004285:Dogs / Q000502:physiology*; D004943:Esophagogastric Junction; D009119:Muscle Contraction / Q000187:drug effects*; D009129:Muscle Tonus / Q000187:drug effects; D009130:Muscle, Smooth / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine; D013270:Stomach
chemical_list: D009599:Nitroprusside; D009543:Nifedipine; D000109:Acetylcholine; D009638:Norepinephrine