Plasma from patients with inflammatory dilated cardiomyopathy

(DCMi) contains antibodies against cardiac antigens. Removal of immunoglobulin G (IgG) from plasma of DCMi patients by im- munoadsorption improves hemodynamic parameters in many patients. The aim of the current study was to test effects of IgG from DCMi patients on cardiac L-type Ca2+ channels. Ca2+ cur- rents were recorded from rat cardiomyocytes while applying 300 mg/l IgG. The IgG fraction of a DCMi patient reduced the Ca2+ current amplitudes of the test cells in average by 25 % compared to the value in physiological solution (n=11 cells). IgG fractions from five other patients showed similar but minor effects. The kinetics of Ca2+ currents was changed by DCMi-IgG. The time constants of inactivation of current transients decreased from 62 ± 12 ms to 47 ± 5 ms in the presence of DCMi-IgG (n=11). Both effects were widely reversible after wash-out. IgG fractions from five healthy donors showed only slight inhibitory effects on Ca2+ currents analysed under the same conditions. We conclude that immunoglobulins from DCMi patients can interfere with cardiac calcium channels. This may contribute to the negative inotropic effect of immunoglobulins on cardiac muscle observed in these patients. (Supported by DFG, SFB-TR 19, project C2)