Characterization of catecholamine release from deer adrenal medullary chromaffin cells

Isolated adrenal medullary chromaffin cells maintained in culture have been widely used to study neurosecretory events. Many of these studies have been conducted using cells obtained from the bovine adrenal. In this study we have cultured chromaffin cells from an alternative large animal model, the deer, and have conducted the first characterization of secretion from this preparation. Cervine chromaffin cells, preloaded with [3H]noradrenalin, displayed a strong secretory response to the cholinergic agonist carbachol, with a maximal secretion of approximately 28% cell content over 15 min. This response was reproduced by nicotinic but not muscarinic agonists and was similarly inhibited by nicotinic but not muscarinic antagonists. Nicotine-evoked secretion measured over a 15 min time period was inhibited approximately 50% by the L-type Ca2+-channel antagonist nifedipine and approximately 20% by N-type (omega-conotoxin GVIA) or N, P/Q-type (omega-conotoxin MVIIC) antagonists. In contrast the response was unaffected by omega-agatoxin IVA, a P/Q-type antagonist. In addition to nicotinic receptor stimulation, activation of PACAP or histamine H1 receptors resulted in a concentration-dependent increase in secretion. PACAP was approximately two-fold more effective than histamine although both were weaker secretagogues than nicotine. In contrast, cervine chromaffin cells did not respond to angiotensin II or bradykinin, two agents known to stimulate secretion from bovine chromaffin cells. These data provide an initial characterization of the secretory response from cervine adrenal medullary chromaffin cells indicating that there are marked similarities but also potentially significant differences between them and their far more extensively described bovine counterparts.