Characteristics of transient outward potassium channel exposed to 3 mT static magnetic field

Abstract

Abstract：Acutely isolated mouse hippocampal CA3 pyramidal neurons were exposed to 3 mT static magnetic field, and the characteristics of transient outward K + channel were studied using the whole-cell patch-clamp technique. The experiment revealed that the amplitude of transient outward potassium channel current was reduced. The maximum activated current densities of control group and exposure group were 163.62±20.68 pA/pF and 98.74±16.57 pA/pF(n=12, P<0.01)respectively. The static magnetic field exposure affected the activation and inactivation process of transient outward potassium channel current. Due to the magnetic field exposure, the halfactivation voltage of the activation curves changed from 5.59±1.96 mV to 27.87±7.24 mV(n=12, P<0.05), and the slope factor changed from 19.43±2.11 mV to 25.87±4.22 mV(n=12, P<0.05). The half-inactivation voltage of the inactivation curves also changed from -56.09±0.89 mV to -57.16±1.10 mV(n=12, P>0.05)and the slope factor of the inactivation curves from 8.69±0.80 mV to 10.87±1.02 mV(n=12, P<0.05). The results show that the static magnetic field can change the characteristics of transient outward K + channel, and affect the physiological functions of neurons.In modern life, the increase of electrical instruments induces exposure to electromagnetic fields, and their possible impacts on biological systems are of great interest [1][2][3][4][5][6][7][8][9] .Most of the current research on the effects of nervous system inflicted by magnetic field is based on the levels of entire body or organs of creatures. The patchclamp technique studies from the perspective of cell ion channels [10][11][12] . The voltage-gated ion channel is the molecular basis of the electronic activity of neurons. For instance, transient outward potassium channel current I A is the main component of the outward current in the early stage of action potential repolarization. In addition, the research on the influence of the static magnetic field with several mT magnitude on biological tissue [13,14] , seldom uses the patch-clamp technique skills.In this paper, the effects of 3 mT static magnetic field (SMF) on transient outward potassium channel currents in hippocampal neurons of a mouse were studied using the whole-cell patch-clamp technique. The work was undertaken to probe the possible molecular mechanisms for SMF-induced bio-stimulation effects. Materials and methods Cell preparation and solutionsHippocampal CA3 pyramidal neurons were freshly isolated by enzymatic digestion and mechanical dispersion from 8 -12-day-old Kunming mice (supplied by Tianjin Medical University). The method used here was similar to that of Ref. [15]. Briefly, 400-500 μm thick brain slices were cut from hippocampal CA3 region and incubated for 50 min at room temperature in artificial cerebrospinal solution (ACS, mmol/L) containing NaCl 134, KCl 5, NaH 2 PO 4 1.5, MgSO 4 2, CaCl 2 2, NaHCO 3 25, glucose 10, HEPES 10, pH adjusted to 7.3, continuously bubbled with 95%O 2 +5%CO 2 and successively transferred into ACS containing 0.3 mg...