Bursts of potential elicited by d-amphetamine in central snail neuron: effect of sodium azide

Effects of sodium azide (NaN(3)) on spontaneously generated action potential and bursts of potential elicited by d-amphetamine (d-amphetamine-elicited BoP) were studied on the right parietal 4 (RP4) neuron of the snail Achatina fulica Ferussac in vitro. Sodium azide altered the spontaneous action potential of RP4 neuron in a concentration-dependent manner. In lower concentrations, neither NaN(3) (30, 100, 300 microM; 1 and 3 mM) nor d-amphetamine (135 microM) affect the resting membrane potential, amplitude and frequency of RP4 neurons, while in the higher concentrations NaN(3) (30 mM) did abolish the spontaneous action potential on RP4 neurons and depolarized the RP4 neurons reversibly. At lower concentration, NaN(3) (30 microM) facilitated the d-amphetamine-elicited BoP. The BoP elicited by NaN(3) (30 microM) and d-amphetamine (135 microM) were decreased following treatment with KT5720 (protein kinase A inhibitor), or intracellular injection of EGTA [ethylene glycol-bis(2-aminoethyl ether)-N,N,N',N'-tetraacetic acid]. However, the BoP was not affected by applying U73122 (1-[6-[((17beta)-3-methoxyestra-1,3,5[10]-trien-17-yl)amino]hexyl]-1H-pyrrole-2,5-dione) or neomycin (phospholipase inhibitors). Voltage clamp studies revealed that NaN(3) (30 microM) did not alter the total fast inwards currents (70 msec.) and the steady-state outwards currents (5 sec.). It appeared that the BoP elicited by NaN(3) (30 microM) and d-amphetamine (135 microM) was mainly due to protein kinase A-related messenger system and intracellular calcium. It is concluded that d-amphetamine-elicited BoP was not mainly due to inhibition of the function of mitochondria in the neuron while the function of mitochondria did alter the BoP elicited by amphetamine.