title: Angiotensin II potentiates neurally mediated contraction of rabbit airway smooth muscle.
abstract: The effect of angiotensin II (AT II) on cholinergic neurotransmission in rabbit tracheal segments was studied under isometric conditions in vitro. AT II concentration-dependently potentiated the contractile response to electrical field stimulation (EFS), and caused a leftward shift of the frequency-response curves for EFS, so that the stimulus frequency required to produce a half-maximal effect (ES50), decreased from 7.0 +/- 0.1 to 3.0 +/- 0.1 Hz (P less than 0.01). In contrast, the contractile response to acetylcholine was not affected. Non-peptide AT II receptor antagonist CV-2961 attenuated the effect of AT II on the EFS-induced contraction. Pretreatment of tissues with thiorphan or phosphoramidon did not alter the action of AT II. Thus, AT II may prejunctionally potentiate the neurally-mediated contraction of airway smooth muscle through activation of AT II receptors on the cholinergic nerve terminals, and this effect may not be modulated by endogenous neutral endopeptidase.
authors.affiliation: First Department of Medicine, Tokyo Women's Medical College, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Yamawaki
authors.forename: J
authors.initials: J
authors.lastname: Tamaoki
authors.forename: F
authors.initials: F
authors.lastname: Yamauchi
authors.forename: K
authors.initials: K
authors.lastname: Konno
mesh_terms: D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000502:physiology*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology*; D015260:Neprilysin / Q000378:metabolism; D010275:Parasympathetic Nervous System / Q000502:physiology; D010830:Physostigmine / Q000494:pharmacology; D011817:Rabbits; D012132:Respiratory Muscles / Q000294:innervation / Q000502:physiology*; D014132:Trachea / Q000502:physiology
chemical_list: D057911:Angiotensin Receptor Antagonists; D007093:Imidazoles; D000804:Angiotensin II; C058909:S 8308; D010830:Physostigmine; D015260:Neprilysin