MAGNESIUM AND NICOTINERGIC EFFECTS ON CATECHOLAMINE RELEASE FROM CHROMAFFIN CELLS

In an in vitro model, the perifused posterior cardinal vein of the eel , norepinephrine (NE) and epinephrine (E) are released from the equiva lent of the adrenal medulla, while dopamine (DA) probably derives from vascular tissue. A low concentration of nicotine (250 ng/ml) stimulat es the release of NE, while a higher concentration (1 mu g/ml) stimula tes the release of all three catecholamines. Magnesium (5.6 mM) reduce s NE and E release without a significant effect on DA release. Nicotin e overrides the magnesium effect. The differential catecholamine respo nses to magnesium may contribute to the anti-stress effect of magnesiu m seen in vivo.