Involvement of Na+/K(+)pump in fine modulation of bursting activity of the snail Br neuron by 10 mT static magnetic field

Abstract

The spontaneously active Br neuron from the brain-subesophageal ganglion complex of the garden snail Helix pomatia rhythmically generates regular bursts of action potentials with quiescent intervals accompanied by slow oscillations of membrane potential. We examined the involvement of the Na+/K+ pump in modulating its bursting activity by applying a static magnetic field. Whole snail brains and Br neuron were exposed to the 10-mT static magnetic field for 15 min. Biochemical data showed that Na+/K+-ATPase activity increased almost twofold after exposure of snail brains to the static magnetic field. Similarly, P-31 NMR data revealed a trend of increasing ATP consumption and increase in intracellular pH mediated by the Na+/H+ exchanger in snail brains exposed to the static magnetic field. Importantly, current clamp recordings from the Br neuron confirmed the increase in activity of the Na+/K+ pump after exposure to the static magnetic field, as the magnitude of ouabain's effect measured on the membrane resting potential, action potential, and interspike interval duration was higher in neurons exposed to the magnetic field. Metabolic pathways through which the magnetic field influenced the Na+/K+ pump could involve phosphorylation and dephosphorylation, as blocking these processes abolished the effect of the static magnetic field.