Fig. 1.

Spontaneous action potentials recorded in current-clamp mode from HL-1 mouse cardiomyocytes. Control traces (blue) contained only lipopolysaccharide (LPS) binding protein (LBP; 10 ng/ml) in the external solution. Traces (red) were recorded 20 min after LPS endotoxin (Salmonella enteritidis) plus LBP were added to external solution at 1 μg/ml. Arrows and numbers indicate the magnitude of transmembrane voltage. Inset: overlay of actions potentials selected from each set to compare pacemaker potential and action potential duration. Dashed lines indicate thresholds at the foot of the action potentials.