Volume 22, Issue 2, Pages 87-93 (June 2015) Hypomagnesemic down-regulation of L-type Ca2+ channel in cardiomyocyte as an arrhythmogenic substrate in rats  Toru Shimaoka, Yan Wang, Masaki Morishima, Shinji Miyamoto, Katsushige Ono  Pathophysiology  Volume 22, Issue 2, Pages 87-93 (June 2015) DOI: 10.1016/j.pathophys.2015.01.002 Copyright © 2015 Elsevier B.V. Terms and Conditions

Fig. 1 Hypomagnesemic changes in serum and myocardial magnesium (Mg) concentration and heart weight. (A) Time dependent changes in serum Mg concentration in Mg-deficient rats. (B) Mg content in myocardium derived from rats with a control diet (control) and an Mg-free diet (hypo Mg) at week 16. (C) Heart weight/body weight ratio in control rats and hypomagnesemic rats at week 16. *p<0.05 compared with week 0 or control. Pathophysiology 2015 22, 87-93DOI: (10.1016/j.pathophys.2015.01.002) Copyright © 2015 Elsevier B.V. Terms and Conditions

Fig. 2 Changes in ECGs in hypomagnesemic rat demonstrating atrioventricular conduction defect and bradycardic premature contraction. Representative ECGs recorded at week 0 (A), week 12 (B), and week 12 with atrioventricular conduction block at week 12 (C). Typical ECGs demonstrating bradycardic ventricular premature contraction (D), Mobitz II atrioventricular block (E), and complete atrioventricular block (F). ECG records (A), (B) and (C) were from a single rat. ECG records (D), (E) and (F) were from three distinct rats during hypomagnesemic condition at week 12. Pathophysiology 2015 22, 87-93DOI: (10.1016/j.pathophys.2015.01.002) Copyright © 2015 Elsevier B.V. Terms and Conditions

Fig. 3 Reduction of ICa.L in hypomagnesemic rat cardiomyocytes. (A) Representative ICa.L current family traces at −35mV to +50mV with 5mV increments from a holding potential of −40mV. Upper panels for traces from ventricular myocytes from a control rat, and lower panels for traces from ventricular myocytes from hypomagnesemic rat at week 12. (B) Current–voltage (I–V) relationships of ICa.L in ventricular myocytes obtained from eight control rats and eight hypomagnesemic rats at week 12. Group data representing the maximum inward ICa.L at the test potentials of +5mV (C), and the chord conductance at the ranges from +15mV to 35mV (D). I–V relationship of ICa.L in control (○) and hypomagnesemic rat cardiomyocytes (●). *p<0.05, compared with hypomagnesemic cardiomyocytes. Pathophysiology 2015 22, 87-93DOI: (10.1016/j.pathophys.2015.01.002) Copyright © 2015 Elsevier B.V. Terms and Conditions

Fig. 4 Changes in mRNA expression for the L-type Ca2+ channel (CaV1.2, CaV1.3) and T-type Ca2+ channel (CaV3.1, CaV3.2). (A) Base line expression of CaV1.2 and CaV1.3 isoforms in the right ventricle in control rats. (B) Relative mRNA expression of CaV1.2 and CaV1.3 isoforms in cardiomyocytes derived from hypomagnesemic rats at week 12. (C) Base line expression of CaV3.1 and CaV3.2 isoforms in the right ventricle in control rats. (D) Relative mRNA expression of CaV3.1 and CaV3.2 isoforms in cardiomyocytes derived from hypomagnesemic rats at week 12. Data were calculated by 2−ΔΔCT and normalized to GAPDH, then compared with cardiomyocytes from control rats (n=6). Pathophysiology 2015 22, 87-93DOI: (10.1016/j.pathophys.2015.01.002) Copyright © 2015 Elsevier B.V. Terms and Conditions