On the uptake and storage of 5-hydroxytryptamine, 5-hydroxytryptophan and catecholamines by adrenal chromaffin cells and nerve endings.
Light-microscopic autoradiographs of the adrenal medulla at various intervals after the intravenous injection of [3H] 5-HTP, [3H] 5-HT, [3H] noradrenaline and [3H] adrenaline have been studied. The distribution of silver grains following [3H] 5-HTP uptake was found to be uniform over each of the two main cell populations, adrenaline-storing (A) cells and noradrenaline-storing (NA) cells in the adrenal medulla, but A cells were twice as active as NA cells in incorporating the isotope, a situation very similar to that found after [3H] dopa uptake. 5-HT administration resulted in a pattern resembling the distribution of [3H] noradrenaline uptake, with A cells being 4 or 5 times more active than NA cells and a gradient of activity from the periphery of the medulla inwards. However, the time-course for the loss of radioactivity was not the same for both amines: levels of 5-HT activity were not significantly reduced after one week whereas the degree of [3H] noradrenaline labelling after one week was less than 10% of that at one hour. Thus 5-HT may be bound to sites in the adrenal medulla normally occupied by noradrenaline but it would appear that the release mechanism is different. There was no evidence of 5-HT uptake by adrenal nerve endings.
D006916:5-Hydroxytryptophan / Q000378:metabolism*; D000313:Adrenal Medulla / Q000294:innervation / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D001345:Autoradiography; D001692:Biological Transport; D002837:Chromaffin Granules / Q000378:metabolism* / Q000648:ultrastructure; D002838:Chromaffin System / Q000378:metabolism*; D004837:Epinephrine / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008854:Microscopy, Electron; D009638:Norepinephrine / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D014316:Tritium
D014316:Tritium; D012701:Serotonin; D006916:5-Hydroxytryptophan; D009638:Norepinephrine; D004837:Epinephrine