How messengers modulate the shifting of spontaneously generated action potential into bursts of potentials (BoP) is studied electrophysiologically and biochemically in RP 1 and 4 neurons of the African snail, Achatina fulica Ferussac using d- and l-amphetamine (Amp) as modulator. The stereospecific effects, extracellular and intracellular ionic effects, messenger related to enzymatic effects and membrane ionic currents effects on BoP elicited by Amp are studied. The roles of organelles, such as mitochondria, protein syntheis related endoplasmic-reticulum, on the BoP are also tested. The messengers modulated the BoP are discussed.