MATERIAL and METHODS: By using an action potential simulation, the effects of extracellular sodium (Na) concentration on the Na ion channel kinetics were studied. The experimental sets were chosen to mimic hypo/hypernatremic conditions and, in both cases, the degree of the severity was varied.

RESULTS: Hyponatremic situations through modifying the axonal Na+ channels kinetics result in the rundown of the sodium current (INa). The degree of the hyponatremia-dependent effect seen in the Na ion channel is severity dependent, which is more effective in the recovery phase of the ion channel. Hypernatremic conditions, on the other hand, have also affected the Na ion channel activity through modifying the kinetics of the channel. Unlike hyponatremia, the effect seen in hypernatremic conditions was through decreasing the response time of the channel. The degree of the significance of the effect seen on the Na ion channel in the case of the hypernatremia was found to be less destructive compared to the hyponatremic condition.

CONCLUSION: The Na channels are susceptible to the changes of the extracellular Na concentrations. Thus, the underestimation of hypo/hypernatremic conditions can put patients in danger and close monitoring of serum Na level might be required. Keywords : Axonal action potential, Ion concentration, Ion channel, Simulation