Non-neurogenic adrenal catecholamine release in the neonatal rat: exocytosis or diffusion?
When subjected to stress, neonatal rats secrete adrenal catecholamines by a mechanism which does not require nerve stimulation. To test whether the non-neurogenic secretory mechanism involves exocytosis, we examined the effects of hypoxia (a non-neurogenic stimulus) and nicotine (a stimulus which simulates neurogenic input) on catecholamine levels and on the uptake of [3H]epinephrine into chromaffin granules. Hypoxia- and nicotine-induced depletion of catecholamines were both accompanied by a reduction in uptake, indicating a loss of granule integrity which is characteristic of exocytosis. Although a significant proportion of adrenal catecholamines was found to be extragranular, only the granular pool was involved in the secretory response.
D000313:Adrenal Medulla / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D002395:Catecholamines / Q000378:metabolism*; D002837:Chromaffin Granules / Q000378:metabolism; D004058:Diffusion; D005089:Exocytosis; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D009538:Nicotine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D002395:Catecholamines; D009538:Nicotine