On the uptake and storage of 5-hydroxytryptamine, 5-hydroxytryptophan and catecholamines by adrenal chromaffin cells and nerve endings |
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Authors: | C Kent R E Coupland |
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Affiliation: | (1) Department of Human Morphology, University of Nottingham, Nottingham, England;(2) Department of Human Morphology, The Medical School, Queen's Medical Centre, NG7 2UH Nottingham, UK |
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Abstract: | Summary 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. |
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Keywords: | Adrenal medulla 5-Hydroxytryptamine 5-Hydroxytryptophan Noradrenaline Autoradiography |
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