Turk Neurosurg, 2017 | 1 Corresponding author: Murat AYAZ E-mail: ayaz72@yahoo.com Original Investigation DOI: 10.5137/1019-5149.JTN.20238-17.2 Received: 28.02.2017 / Accepted: 21.04.2017 Published Online: 05.06.2017 qr code Murat AYAZ 1 , Hakan KARABAGLI 2 , Sirma Basak YANARDAG 1 1 Selcuk University, School of Medicine, Department of Biophysics, Konya, Turkey 2 Selcuk University, School of Medicine, Department of Neurosurgery, Konya, Turkey Can Hypo/Hypernatremic Conditions be a Factor for Na Ion Channel Kinetics: Model Study ABSTRACT adequate to open the Na+ channel, the AP is generated and transferred throughout the axon length without any change in the confguration. However if the graded potential is not suffcient to open a Na+ channel, no AP is observed (29). Na+ channels have three conformations in their mode of action which are open, inactive and closed. These modes not only determine the formation of the AP, but also determine the frequency response of the AP under continuous stimulation (16). There are at least two issues that are important in the formation of the current through the ion channel. The frst one is the internal properties of the channel (conductivity parameters) and the second one is the ionic gradient across the ion █ INTRODUCTION A ction potential (AP), a rapid rise and fall in the electrical membrane potential of a neuron, which is commonly called “fring”, is the basis of signal transmission through a single neuron. An adequate amount of neurotransmitter concentration in the synaptic space creates a series of reactions resulting in rapid activation of sodium (Na) channels, which is called the zero phase (depolarization phase). Na+ currents (INa) -for all of the excitable tissue types- can be named universal depolarizing currents whereas the K+ currents (IK) are repolarizing currents (6). The all or none characteristic of the AP actually comes from the Na+ channel’s properties. When the graded potential is AIm: Dysnatremic cases are frequently faced in clinical practice. Its macroscopic effects and consequences are well known, but microscopic effects are not well defned. The aim of this study was to reveal the effects of dysnatremia at the cellular level. 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 signifcance 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