Effect of chronic administration of furosemide and thiamine on isolated heart in rat

Diuretics can induce thiamine deficiency which develops cardiac failure. This study aimed to examine the effect of chronic administration of thiamine and furosemide, as a most commonly used diuretic, on the mechanical activity of heart in the isolated rat heart. In this experimental study, rats were divided into three groups (n=8 for each group): the control group (C) received no drug, the furosemide group (FUR) received furosemide (2 mg/Kg) daily for 53 days and the furosemide+thiamine group (FUR+THI) received furosemide (2 mg/Kg)+thiamine (70 mg/kg) daily for 53 days via drinking water. At the end of the experiment, using isolated heart, heart rate and mechanical activity were recorded during baseline and at 1 (EP1) and 5 (EP5) minutes after the addition of epinephrine to the bath. Heart contractility was increased in the FUR+THI group compared to the FUR and C groups at baseline and EP1. Moreover, contractility in the FUR+THI group was higher than the C group at Ep5. Contraction velocity and heart rate were increased at all three points in FUR+THI group compared to the C and FUR groups, while contraction velocity in FUR group only at EP1 and EP5 was significantly higher than the C group. Heart rate in FUR+THI group was higher than the C and FUR groups at all three points; heart rate in FUR group at baseline was significantly higher than the C group. Co-administration of thiamine and furosemide has positive inotropic and chronotropic effects on the isolated heart, but the possible mechanisms for these effects need further research.