Effects of angiotensin peptides on cholinergic neurotransmission in rabbit tracheal smooth muscle.
To determine the effects of angiotensins I, II, and III (A I, A II, and A III) on airway smooth muscle functions, we studied isolated tracheal segments from rabbits under isometric conditions in vitro. Addition of A II and A III but not A I potentiated the contractile response to electrical field stimulation (EFS) at 5 Hz in a dose-dependent fashion. The frequency-response curves for EFS were displaced to the left by A II and A III, whereas the contractile responses to exogenous acetylcholine remained unchanged. Angiotensin-induced potentiation of the response to EFS was further increased in the presence of physostigmine. These results suggest that A II and A III may prejunctionally potentiate the vagally-mediated contraction of airway smooth muscle.
Tamaoki
J
J
First Department of Medicine, Tokyo Women's Medical College, Japan.
Yamauchi
F
F
Konno
K
K
D000109:Acetylcholine / Q000494:pharmacology; D000803:Angiotensin I / Q000494:pharmacology*; D000804:Angiotensin II / Q000494:pharmacology*; D000805:Angiotensin III / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000294:innervation / Q000502:physiology; D010275:Parasympathetic Nervous System / Q000187:drug effects; D010830:Physostigmine / Q000494:pharmacology; D011817:Rabbits; D009435:Synaptic Transmission / Q000187:drug effects*; D014132:Trachea / Q000187:drug effects / Q000294:innervation
D000804:Angiotensin II; D000805:Angiotensin III; D000803:Angiotensin I; D010830:Physostigmine; D000109:Acetylcholine