Calcitonin gene-related peptide augments parasympathetic contraction of rabbit tracheal smooth muscle in vitro.
The effect of calcitonin gene-related peptide (CGRP) on parasympathetic contraction of rabbit airway smooth muscle was studied under isometric conditions in vitro. CGRP (10(-7) M) did not contract tracheal smooth muscle, but it potentiated the contractile response to electrical field stimulation (EFS) in a dose-dependent manner, the maximal increase from the baseline response being 14.4 +/- 6.2%. In contrast, the contractile responses to exogenously administered acetylcholine were not altered by this peptide. The CGRP-induced potentiation of the contractile responses to EFS was further augmented by physostigmine (123.1%), but not influenced by phentolamine, propranolol, indomethacin, or thiorphan, an enkephalinase inhibitor. These results suggest that CGRP augments the neurally mediated contraction of rabbit airway smooth muscle probably through a prejunctional mechanism and that this effect may not be modulated by tissue enkephalinase.
Kanemura
T
T
First Department of Medicine, Tokyo Women's Medical College, Japan.
Tamaoki
J
J
Horii
S
S
Sakai
N
N
Kobayashi
K
K
Isono
K
K
Takeuchi
S
S
Takizawa
T
T
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology*; D004558:Electric Stimulation; D009119:Muscle Contraction / Q000187:drug effects*; D015260:Neprilysin / Q000037:antagonists & inhibitors; D010275:Parasympathetic Nervous System / Q000502:physiology*; D010830:Physostigmine / Q000494:pharmacology; D011817:Rabbits; D015244:Thiorphan / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects / Q000502:physiology*
D001285:Atropine; D010830:Physostigmine; D015244:Thiorphan; D015260:Neprilysin; D015740:Calcitonin Gene-Related Peptide; D000109:Acetylcholine