[Effect of catecholamines on the smooth muscles of the esophageal groove of calves].
The effect of noradrenaline and adrenaline on isolated smooth muscle from the reticular groove of calves was studied. Both catecholamines caused a concentration-dependent (1.1.10(-6) mol/l) contraction of the transversal muscle strips from the floor of the reticular groove. This excitatory effect was antagonized by prazosin (10(-7)) mol/l), and by high concentrations of yohimbine (10(-6) mol/l) and atropine (10(-5)) mol/l). Tetrodotoxin (3.10(-6) mol/l), an inhibitor of nerve conduction, did not change the contraction induced by catecholamines (55.10(-6)) mol/l). Catecholamines did not produce a contraction of the longitudinal muscle from the lips of the reticular groove. The beta-adrenergic agonist isoprenaline (55.10(-6) mol/l) even elicited a reduction of acetylcholine (55.10(-6)) mol/l) induced contraction of both the transversal and the longitudinal muscle from the reticular groove. The relaxing effect of isoprenaline was antagonized by propranolol (55.10(-6)) mol/l). According to these results the excitatory effect of catecholamines on the smooth muscle cells occurs through alpha-adrenergic receptors, whereas the relaxing effect is mediated by beta-adrenergic receptors of the muscle cell. The excitatory effect of catecholamines on the transversal muscle appears to be predominant. Atropine appears to be an unspecific blocking agent of alpha-adrenergic receptors.
Denac
M
M
Institut für Veterinärphysiologie, Universität Zürich.
Marti
J
J
Scharrer
E
E
D000818:Animals; D002417:Cattle / Q000502:physiology*; D004837:Epinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004947:Esophagus / Q000187:drug effects*; D005260:Female; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D012159:Reticulum / Q000187:drug effects*
D009638:Norepinephrine; D004837:Epinephrine
Einfluss von Katecholaminen auf die glatte Muskulatur der Schlundrinne des Kalbes.