Fig. 1

Representative traces showing that glucagon did not exert inotropic effects on the failing human myocardium. Increasing concentrations of glucagon (1–1000 nM) were added to trabecular strips obtained from the right atrium (RA), left atrium (LA), right ventricle (RV) and left ventricle (LV) obtained from a failing heart. After being washed (W), the samples were allowed to stabilize for 30 min, and then the nonselective phosphodiesterase inhibitor IBMX (30 μM) was applied and left in contact with the tissue for 15 min. Afterwards, increasing concentrations of glucagon (1–1000 nM) were again applied to all samples, and again, no inotropic effect was observed. Experiments were finalized with the addition of 9 mM CaCl₂ to determine the responsiveness of the samples