1. Physiological Pathway of Magnesium Influx in Rat Ventricular Myocytes
Michiko Tashiro, Hana Inoue, Masato Konishi 
Biophysical Journal 
Volume 107, Issue 9, Pages (November 2014)
DOI: /j.bpj
Copyright © 2014 Biophysical Society Terms and Conditions

2. Figure 1
Examples of experimental runs for Mg2+ influx in various extracellular solutions. After Mg2+ depletion, the cell was perfused with (A) Ca2+-free Tyrode’s solution, (B) 5 mM-Mg2+ Tyrode’s solution, (C) NMDG Tyrode’s solution, or (D) high-K+ solution. In each run, the estimated values of [Mg2+]i (dots) were fitted by a single exponential function (solid line). A dotted line shows the basal level of [Mg2+]i of each cell measured in Ca2+-free Tyrode’s solution just before Mg2+ depletion.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2014 Biophysical Society Terms and Conditions

3. Figure 2
(A) A representative time course of the [Mg2+]i recovery calculated with mean values of τ, A, and [Mg2+]i(t = ∞), as shown. The dotted line indicates the mean value of basal [Mg2+]i (0.92 mM). Ten experiments were carried out at 25°C in Ca2+-free Tyrode’s solution. (B) The first derivative of the solid line in A was calculated with Eq. 4, plotted as a function of [Mg2+]i (solid line), and extrapolated for [Mg2+]i < 0.347 mM (broken line).
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2014 Biophysical Society Terms and Conditions

4. Figure 3
Effects of (A) 2-APB, (B) NS8593, and (C) spermine on the Mg2+ influx rate. All values of d[Mg2+]i(t)/dt were normalized to those expected for the initial [Mg2+]i to calculate relative Mg2+ influx rates (see text for details). Each symbol represents mean ± SE of data obtained from five to ten cells. Solid lines indicate the least-squares fit of the data set by the Hill-type curve with parameter values shown in the panel as follows:RelativeMg2+influxrate=max+(min-max)([X]NKiN+[X]N),where the maximum (max) and minimum (min) are relative Mg2+ influx rates, respectively, in the absence of the inhibitor and in the presence of saturating concentrations of the inhibitor (a lower bound set to 0). N and Ki are, respectively, Hill coefficient and IC50. To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2014 Biophysical Society Terms and Conditions

5. Figure 4
(A) A short-term continuous recording of [Mg2+]i recovery in the cells depleted of Mg2+. The Mg2+ influx was induced in Ca2+-free Tyrode’s solution with NH4Cl (20 mM) included only for the initial 2 min (shaded area). EIPA (5 μM) was present in the bathing solutions throughout the run. (B) An example of the [Mg2+]i recovery for 180 min after washout of NH4Cl (dots). Solid and dotted lines indicate, respectively, the least-squares fitted exponential function and the basal level of [Mg2+]i, as described in the legend of Fig. 1. To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2014 Biophysical Society Terms and Conditions

6. Figure 5
(A) In vitro excitation spectra of furaptra measured in the solutions that contained 0-5 μM NiCl2 (as indicated) at 25°C. (B) Fluorescence quenching of intracellular furaptra by Ni2+. For each cell, furaptra F(350) was followed as a function of time after extracellular application of 1 mM NiCl2 at time 0. In addition to 1 mM Ni2+, the bathing solution contained either 0 mM Mg2+ for circles (○ and ●) or 1 mM Mg2+ for triangles (▵ and ▴). Relative F(350) was defined as the F(350) value normalized to that measured just before application of NiCl2. Each symbol represents mean ± SE. Solid circles (●): five cells with normal basal [Mg2+]i (initial [Mg2+]i 0.77 ± 0.04 mM). Open circles (○): six cells depleted of Mg2+ (initial [Mg2+]i 0.35 ± 0.03 mM). Solid triangles (▴): six cells with normal basal [Mg2+]i (initial [Mg2+]i 0.73 ± 0.07 mM). Open triangles (▵): six cells depleted of Mg2+ (initial [Mg2+]i 0.38 ± 0.04 mM). (C and D) Concentration-dependent inhibition of Ni2+ influx by (C) 2-APB and (D) NS8593 obtained in Mg2+-depleted cells. For each cell, the initial rate of decrease in F(350) was estimated by linear least-squares fit to data points in the initial 10 min, and was normalized to the mean value obtained in the absence of any inhibitors (open circles in B) to yield the relative initial rate. Each symbol represents mean ± SE from four to six cells. Solid lines were drawn by least-squares fit of the data sets with the Hill-type curve, as described in the legend of Fig. 3. All parameter values are shown in the panels. To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2014 Biophysical Society Terms and Conditions

7. Figure 6
Changes in [Mg2+]i during Mg2+ depletion of the cells at 35°C. Examples of data from three cells are shown. The cells were depleted of Mg2+ in the absence of any inhibitors of TRPM7 (solid circles) and in the presence of either 100 μM 2-APB (open circles) or 10 μM NS8593 (Xs). Solid, broken, and dotted lines were drawn by least-squares fit of solid circles, open circles, and Xs, respectively, by the single exponential function.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2014 Biophysical Society Terms and Conditions

8. Figure 7
Effects of TRPM7 inhibitors on IMIC. (A) A typical record of the membrane currents, showing the inward current at −120 mV (red dots) and the outward current at +60 mV (black dots). The divalent-free solution (DVF) and then 2-APB (100 μM 2-APB) were applied during the periods indicated by horizontal bars. (B) I-V relations obtained from the experiment shown in A at cell membrane rupture (black), in the divalent-free solution just before 2-APB application (red) and 140 s after the application of 2-APB (blue). (C) Each symbol represents the mean ± SE of the inward current amplitude at −120 mV normalized to that just before application of 2-APB. A concentration-response curve for 2-APB (red) was drawn by least-squares fit of the data set by the Hill type curve, as described in the legend of Fig. 3, with the max set to 1.0. (D) The membrane currents were measured at −120 mV (red dots) and at +60 mV (black dots), and the divalent-free solution was applied during the period indicated by a horizontal bar (DVF), as in A. NS8593 (10 μM) was then applied, as indicated. To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2014 Biophysical Society Terms and Conditions