Histamine-induced potentiation of cholinergic transmission in chick oesophagus (Gallus gallus)

1. The effects of histamine on cholinergic nerve transmission were investigated in the oesophagus of the chick (0-29 days old). 2. Histamine potentiated the contractile responses produced by vagal or transmural nerve stimulation and by the ganglionic stimulant (DMPP) with the increase of tonus of oesophagus. On the other hand, a selective H2 agonist, 4-methylhistamine, did not have any effect. 3. The sensitivity of oesophagus to ACh did not change in the presence of histamine (0.2-2 microM). 4. Mepyramine but not metiamide antagonized the contractile and potentiating effects of histamine. 5. From these findings, it is concluded that histamine preferentially acts on H1-receptors located in cholinergic neurones to facilitate cholinergic transmission in the chick oesophagus, potentiating the nerve-mediated contraction.