Effects of autoantibodies against β1-adrenoceptor in hepatitis virus myocarditis on action potential and L-type Ca2+ currents

Figure 1 Specific binding of anti-β₁-receptor autoantibodies to guinea pig cardiac myocytes. Rod-shaped cardiac myocytes were stained by immunofluorescence (second IgG labeled with FITC), suggesting the specific binding of anti-β₁-receptor autoantibodies to cardiac myocytes.

Figure 2 AP recordings before and after superfusion with anti-β₁-receptor diluted at 1:80 in the absence and presence of 1 μmol/L metoprolol. A: effect of anti-β₁-receptor diluted an 1:80 on AP. ^arepresents AP before superfusion with 1:80 anti-β₁-receptor autoantibodies, ^brepresents AP after superfusion with 1:80 anti-β₁-receptor autoantibodies. B: no marked changes of AP after superfusion with 1:80 anti-β₁-receptor autoantibod-ies in the presence of 1 μmol/L metoprolol.

Figure 3 Effects of anti-β₁-receptor autoantibodies on peak current amplitude of I_Ca-L in the absence and presence of 1 μmol/L metoprolol. A and B (left): time-course changes of peak cur-rent amplitude of I_Ca-L before and after superfusion with anti-β₁-receptor autoantibodies diluted at 1:80 (A) or in the pres-ence of 1 μmol/L metoprolol (B). A and B (right): traces of I_Ca-L before and after superfusion with anti-β₁-receptor autoanti-bodies diluted at 1:80 (A) or before and after superfusion with anti-β₁-receptor autoantibodies diluted an 1:80 in the pres-ence of 1 μmol/L metoprolol (B). ^arepresents the maximal peak current amplitude of I _Ca-L before superfusion with anti-β₁-receptor autoantibodies diluted at 1:80, ^brepresents the maximal peak current amplitude of I_Ca-L after superfusion with anti-β₁-receptor autoantibodies diluted an 1:80. ^crepresents the maximal peak current amplitude of I_Ca-L after superfusion with anti-β₁-receptor autoantibodies diluted at 1:80 in the pres-ence of 1 μmol/L metoprolol. C: concentration dependence of anti-β₁-receptor autoantibodies. The numbers in brackets in-dicate the number of cells studied at each concentration.

Figure 4 Effects of anti-β₁-receptor autoantibodies diluted at 1: 100 on current-voltage (I-V) relationships normalized to cell membrane capacitance measured in 5 cells (mean ± SEM) dur-ing voltage steps from –40 to +60 mV in the absence (A) and presence of 1 μmol/L metoprolol (B).

Figure 5 Cell toxicity effect of cardiac myocytes exposed to high concentrations of anti-β₁-receptors autoantibodies. A: rod-shaped cells excluding trypan blue. B: rounded cells perme-able to trypan blue.