title: 22Na+ uptake and catecholamine secretion by primary cultures of adrenal medulla cells.
abstract: The uptake of 22Na+ and secretion of catecholamines by primary cultures of adrenal medulla cells under the influence of a variety of agonists and antagonists were determined. Veratridine, batrachotoxin, scorpion venom, and nicotine caused a parallel increase in 22Na+ uptake and Ca2+-dependent catecholamine secretion. Ba2+, depolarizing concentrations of K+, and the Ca2+ ionophore Ionomycin stimulated secretion of catecholamines but did not increase the uptake of 22Na+. Tetrodotoxin inhibited both 22Na+ uptake and catecholamine secretion evoked by veratridine, batrachotoxin, and scorpion venom, but had no effect on 22Na+ uptake and catecholamine secretion caused by nicotine. On the other hand, histrionicotoxin, which blocks the acetylcholine receptor-linked ion conductance channel, blocked nicotine-stimulated 22Na+ uptake and catecholamine secretion, but only partially inhibited veratridine-stimulated catecholamine secretion and had no effect on veratridine-stimulated 22Na+ uptake. The combination of veratridine plus tetrodotoxin, which has been shown to prevent nicotine-stimulated secretion of catecholamines by adrenal medulla cells, also prevented nicotine-stimulated 22Na+ uptake by the primary cultures. These studies demonstrate the presence of tetrodotoxin-sensitive Na+ channels in adrenal medulla cells which are functionally linked to Ca2+-dependent catecholamine secretion. However, These channels are not utilized for Na+ entry upon activation of nicotinic receptors; in this case Na+ entry occurs through the receptor-associated ion conductance channel.
mesh_terms: D000157:Aconitine / Q000494:pharmacology; D000313:Adrenal Medulla / Q000378:metabolism*; D000818:Animals; D001496:Batrachotoxins / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D007473:Ion Channels / Q000378:metabolism*; D007700:Kinetics; D009538:Nicotine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D012604:Scorpion Venoms / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D014701:Veratridine / Q000494:pharmacology
chemical_list: D001496:Batrachotoxins; D002395:Catecholamines; D007473:Ion Channels; D012604:Scorpion Venoms; D013779:Tetrodotoxin; D009538:Nicotine; D014701:Veratridine; D012964:Sodium; D011188:Potassium; D002118:Calcium; D000157:Aconitine