Prostanoid receptors of the EP_3 subtype mediate inhibition of evoked [~3H] acetylcholine release from isolated human bronchi

摘要

The release of neuronal [~3H]acetylcholine (ACh) from isolated human bronchi after labelling with [~3H]choline was measured to investigate the effects of prostanoids. A first period of electrical field stimulation(S_1) caused a [~3H]ACh release of 320±70 and 200±40 Becquerel(Bq) g~-1 in epithelium-denuded and epithelium-containing bronchi respectively (P > 0.05). Subsequent periods of electrical stimulation(S_n, n =2, 3, and 4) released less [~3H]ACh, i.e. decreasing S_n/ S_1 values were obtained (0.76±0.09, 0.68±0.07 and 0.40±0.04, respectively). Cumulative concentrations(1-1000 nM) of EP-receptor agonists like prostaglandin E_2, nocloprost, And sulprostone(EP_1 and EP_3 selective)inhibited evoked[~3H]ACh release in a concentration dependent Manner with IC_50 values between 4-14 nM and maximal inhibition of about 70/100.