title: Release of norepinephrine by sympathetic nerve stimulation from rabbit lungs.
abstract: Rabbit lungs were perfused via the pulmonary artery and norepinephrine (NE) measured in the outflows. The basal NE level was approximately 3 ng/min. Electrical stimulation (50 V, 1 ms, 10 Hz) of the sympathetic nerves doubled the NE release. Hexamethonium (10(-4) and 10(-5) M) had no effect on the release of NE. Administration of a monoamine oxidase (MAO) inhibitor, pargyline (70 mg/kg) resulted in a 20-fold NE increase by nerve stimulation, implying that the bulk of the amine does not reach the systemic circulation due to an active MAO. Methacholine (1 and 10 micrograms/ml) inhibited NE release by nerve stimulation. This inhibition was abolished by atropine (5 micrograms/ml). It is suggested that a muscarinic inhibitory mechanism may regulate the NE release in the lung. PGE2 (100 ng/ml), but not PGS2alpha, (100 ng/ml), depressed NE release during nerve stimulation, whereas indomethacin (10 mg/kg) enhanced NE release before, during, and after nerve stimulation in seemingly normal animals. This indicates the existence of another presynaptic inhibitory mechanism for NE release in the lung: a PGE-mediated inhibition.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004558:Electric Stimulation; D006584:Hexamethonium Compounds / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008168:Lung / Q000294:innervation*; D008297:Male; D008688:Methacholine Compounds / Q000494:pharmacology; D009411:Nerve Endings / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D010293:Pargyline / Q000494:pharmacology; D011458:Prostaglandins E / Q000494:pharmacology; D011460:Prostaglandins F / Q000494:pharmacology; D011817:Rabbits; D013564:Sympathetic Nervous System / Q000378:metabolism*
chemical_list: D006584:Hexamethonium Compounds; D008688:Methacholine Compounds; D011458:Prostaglandins E; D011460:Prostaglandins F; D001285:Atropine; D010293:Pargyline; D000109:Acetylcholine; D009638:Norepinephrine; D007213:Indomethacin