Promena aktivnosti Na+/K+ pumpe i njen uticaj na spontanu bioelektričnu aktivnost neurona vinogradskog puža Helix pomatia L. pod dejstvom magnetnog polja
Change in the activity of Na+/K+ pump and its effect on the spontaneous bioelectric activity of neuron of the garden snail Helix pomantia L. in the magnetic field
Doctoral thesis (Published version)
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It is important to investigate the effects of moderate intensity static magnetic field on the bioelectric activity of neurons, since this field is present in the environment. Equally important is to reveal the mechanism of action of moderate intensity static magnetic field on biophysical properties of neuronal membranes, as this field has been applied in disease treatment, whereby proper dosages of exposure still need to be determined. Comparative intracellular registration studies showed that short term exposure (15 min) to the moderate intensity static magnetic field of 2,7 mT and 10 mT strength changed bioelectric activity of the spontaneously active Br neuron, while bioelectric activity of silent N1 neuron remained unchanged. The 2,7 mT magnetic field increased amplitude and decreased duration of action potential, whereas the 10 mT magnetic field hyperpolarized membrane potential, increased amplitude, decreased firing frequency and duration of action potential of the Br neuron. The magnitude of change of measured bioelectric parameters depended on the strength of applied magnetic field, and was still observed during the period of 20 min after exposure of Br neuron to the 2,7 mT and 10 mT magnetic field. Combined experiments, using biochemical analysis and NMR spectroscopy on whole snail brains and intracellular registration on Br neuron, showed that short-term exposure (15 min) to the 10 mT magnetic field increased activity of Na+/K+ pump. Increased Na+/K+ pump activity in the snail brain caused an increase in ATP consumption and increase in the pHi which is mediated through an increase in the activity of Na+/H+ exchanger, a pH regulatory system governed by the gradient of Na+ ions created and maintained by Na+/K+ pump. Electrophysiology from Br neuron is in agreement with the results obtained on the whole snail brain. Magnitude of ouabain effect measured on the membrane resting potential, action potential and interspike interval duration, was higher in Br neurons exposed to the magnetic field, demonstrating that Na+/K+ pump plays an important role in modulation of bioelectric activity of Br neuron caused by 10 mT magnetic field. Pathways through which the magnetic field influenced the Na+/K+ pump activity involve phosphorylation and dephosphorylation, as blocking these processes abolished the effect of the static magnetic field.
Keywords:Spontaneous bioelectric activity; Static magnetic field; Na+/K+ pump; Intracellular registration; Garden snail
Source:University of Belgrade, Faculty of Biology, 2012, 1-107