Inhibition by prostaglandin E2 of neurotransmission in rabbit but not human bronchus--a calcium-related mechanism?
Prostaglandins have been implicated in the development of airway hyperresponsiveness, and this may be mediated via modulation of neurotransmission. We compared the effects of prostaglandin E2 on the contractile response to electrical field stimulation in rabbit and human bronchus. Prostaglandin E2 produced marked inhibition in rabbit bronchus (mean % inhibition 35 +/- 17, P less than 0.05) but was without effect in human bronchus. The inhibition in rabbit bronchus was not the result of a direct effect on muscle tone and the site of action is likely to be pre-synaptic since prostaglandin E2 had only minor effects on exogenous acetylcholine. Since prostaglandins are known to affect calcium mobilization, we compared the dependence of cholinergic stimulation on the calcium voltage dependent channel (VDC) in the two species. Cholinergic stimulation was dependent on the VDC in rabbit but not human bronchus and this may be an explanation for the different effects of prostaglandin E2 in the two species.
Black
J L
JL
Department of Pharmacology, University of Sydney, Australia.
Johnson
P R
PR
Alfredson
M
M
Armour
C L
CL
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001980:Bronchi / Q000187:drug effects / Q000294:innervation; D002118:Calcium / Q000502:physiology*; D015232:Dinoprostone / Q000494:pharmacology*; D004558:Electric Stimulation; D006801:Humans; D066298:In Vitro Techniques; D008168:Lung / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D011817:Rabbits; D013045:Species Specificity; D009435:Synaptic Transmission / Q000187:drug effects*
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D015232:Dinoprostone; D000109:Acetylcholine; D002118:Calcium