Inhibition by Drugs of the Accumulation in vitro of 5-Hydroxytryptamine in Guinea-pig Vas Deferens

Abstract

AFTER an injection of ¹⁴C-5-hydroxytryptophan, autoradiographic grains were found to accumulate in the sympathetic neurones of the pineal gland and vas deferens¹. These observations suggested that the sympathetic nerves of these organs might take up or retain 5-hydroxytryptamine. Subsequent work has shown that 5-hydroxytryptamine can accumulate in the guinea-pig vas deferens in vitro by an active transport process². Subcellular distribution studies also indicated that the site of accumulation of the 5-hydroxytryptamine is the storage vesicle present in the sympathetic neurone². Certain drugs such as imipramine³ and cocaine⁴ are potent inhibitors of the uptake of noradrenaline into sympathetic neurones, and these drugs also block the uptake of 5-hydroxytryptamine in platelets⁵ and some tissues in the rat⁶. Subsequent work has shown that the site of blockade of noradrenaline uptake is the neuronal membrane⁷. These observations prompted us to investigate the ability of these drugs to block the uptake in the vas deferens of 5-hydroxytryptamine labelled with carbon-14.