The histamine H3-agonist, (R)-α-methylhistamine (α-MeHA) caused a dose-dependent inhibition of cholinergic contractile responses to electrical field stimulation in human bronchi without affecting the basal tone. α-MeHA, but, did not alter the response to acetylcholine. Blockade of H1- and H2-receptors, or α- and β-adrenoceptors failed to prevent the inhibitory effect of α-MeHA, whereas the specific H3-antagonist, thioperamide, was effective. Our results indicate that H3-receptors modulate cholinergic neurotransmission in human airways.
- Electrical field stimulation
- Histamine H-receptor agonists
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