in rats: 3 mg/kg i.v

HMR 1883 (Clamikalant) blocks KATPs in cardiac muscle cells with 10-50 fold higher potency than in pancreatic beta-cells and has little effect on the coronary vascular system. HMR 1883 has pharmacological selectivity for cardiac myocytes and thereby may be a promising substance for the prevention of ischemia-induced ventricular fibrillation. The rilmakalim-induced shortening of the APD90 in guinea pig right papillary muscle was antagonized half-maximally by HMR 1883 with 0.6 uM. The rilmakalim-induced shortening of the APD90 was half-maximally antagonized by HMR 1883 with 0.4 uM. The rilmakalim-induced whole-cell current (at 0 mV clamp-potential) was inhibited by HMR 1883 half-maximally 0.8 uM. Addition of HMR 1883 depolarized the cell potential half-maximally with concentrations of 20 uM.