title: Evidence for alpha-adrenergic innervation of the isolated canine thoracic duct.
abstract: The excitatory innervation of isolated thoracic duct segments was studied using tissue bath techniques. No spontaneous activity was present in longitudinal or helical strips obtained from a portion of the thoracic duct cephalad to the hilum of the lung. Norepinephrine (10(-8) to 10(-5) M) and tyramine (3 x 10(-5) M) produced contractions that were antagonized by phentolamine (2 x 10(-5) M) and phenoxybenzamine (10(-7) M). Acetylcholine (10(-7) to 10(-4) M) produced contractions that were antagonized by atropine (5 x 10(-9) M). Thoracic duct strips also contracted in response to field electrical stimulation, and maximal responses were obtained with a stimulus of 15 V, 15 Hz, and 1-ms pulse duration. These electrically induced contractions were abolished by tetrodotoxin (5 x 10(-7) M), phentolamine (2 x 10(-5) M), phenoxybenzamine (10(-7) M), and guanethidine (3 x 10(-6) M), but not by atropine (10(-6) M). We conclude that smooth muscle of the canine thoracic duct contains alpha-adrenergic and acetylcholine receptors, both of which cause contraction when stimulated. However, only the alpha-receptors appear to be innervated.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004285:Dogs; D004558:Electric Stimulation; D066298:In Vitro Techniques; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000502:physiology*; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology; D013897:Thoracic Duct / Q000294:innervation*; D014439:Tyramine / Q000494:pharmacology
chemical_list: D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D013779:Tetrodotoxin; D001285:Atropine; D011433:Propranolol; D000109:Acetylcholine; D009638:Norepinephrine; D014439:Tyramine; D010646:Phentolamine