Myocardial Function of Hyperthyroid Rats in Presence of Diazepam in Langendorff Setup

Modulation of Ischemia-Reperfusion (I/R) injury is highly important in medicine, especially in hyperthyroidism condition. The effect of diazepam as a benzodiazepine on cardiac I/R injury is also clinically important. The chronic effect of diazepam in this case has been reported previously.. This study aimed to investigate the effect of acute diazepam perfusion on isolated heart of hyperthyroid rats during I/R.. Male rats (n = 32, weighing 250 - 300 gr) were randomly divided into 4 groups: control, hyperthyroid, control diazepam perfused, and hyperthyroid diazepam perfused. Isolated hearts were perfused through Langendorff method. Four sets of data were collected at baseline (20 minutes), diazepam perfusion (10 minutes, 100 µmol/L), ischemia (40 minutes), and reperfusion (45 minutes) periods. Cardiac parameters, including Left Ventricular Developed pressure (LVDP; mmHg) and Rate Pressure Product (RPP; mmHg × beats/min) were measured, as well. Lactate dehydrogenase (LDH; mU/mL) was also assessed for evaluation of I/R injury. The data were analyzed using ANOVA and Student t-test and P < 0.05 was considered as statistically significant.. RPP significantly declined in the hyperthyroid group after diazepam perfusion compared to the baseline (24046 ± 1381 versus 18269 ± 711, P = 0.012, 95% CI: 1724 - 9828). Besides, RPP and LVDP significantly increased in the hyperthyroid diazepam perfused group compared to the hyperthyroid group at the end of the reperfusion period (12469 ± 1422 versus 4007 ± 258, P < 0.001, CI: 5066 - 11856 and 47 ± 2.8 versus 23 ± 2.8, P < 0.001, CI: 11-35, respectively). These findings were confirmed by LDH levels (19.08 ± 1.06 versus 41.07 ± 8.14, P = 0.002, CI: -34.4 - -9.4-35).. The results showed that acute diazepam perfusion to isolated hyperthyroid rats’ hearts could significantly improve cardiac function following ischemia and protect the heart against I/R injury..