Fructose-1,6-diphosphate counteracts potassium effects on cardiac muscle

Fructose-1,6-diphosphate (FDP) counteracts the inhibition of contractile strength of rabbit cardiac muscle induced by KCl "in vitro" and the valinomycin induced depolarization. FDP also protects in a dose-dependent fashion, up to 100 mg/kg, different strains of mice from the lethal effect of KCl that is due to a complete atrio-ventricular block and related to a high value of plasma potassium level. A protective effect of FDP is observed when increasing doses of (+/-) propranolol are injected before maximum non lethal dose of KCl.