Protective Effects of Estradiol on Myocardial Contractile Function Following Hemorrhagic Shock and Resuscitation in Rats

Background: Hemorrhagic shock (HS) results in myocardial contractile dysfunction. Studies showed that 17β-estradiol protects the myocardium against contractile dysfunction. The study investigated the cardioprotective effects of treatment with 17β-estradiol before resuscitation following 1 h of HS and resuscitation.Methods: Male Sprague-Dawley rats were assigned to 2 sets of experimental protocols:Ex vivo andin vivo treatment and resuscitation. Each set had three experimental groups (n = 6 per group): Normotensive (N), HS and resuscitation (HS-R) and HS rats treated with 17β-estradiol (E) and resuscitated (HS-E-R). Rats were hemorrhaged over 60-min to reach a mean arterial blood pressure of 40 mmHg. In theex vivo group, hearts were resuscitated by perfusion in the Langendorff system. In the 17β-estradiol treated group, 17β-estradiol 280 μg/kg was added for the first 5 min. Cardiac function was measured. Left ventricular generated pressure (LVGP) and +dP/dt were calculated. In thein vivo group, rats were treated with 17β-estradiol 280 μg/kg s.c. after 60-min HS. Resuscitation was performedin vivo by the reinfusion of the shed blood for 30-min to restore normotension.Results: Treatment with 17β-estradiol before resuscitation inex vivo treated and resuscitated isolated hearts and in thein vivo treated and resuscitated rats following HS improved myocardial contractile function. In thein vivo treated group, LVGP and +dP/dt max were significantly higher in 17β-estradiol treated rats compared to the untreated group (LVGP 136.40 ± 6.61 compared to 47.58 ± 17.55, and +dP/dt 661.85 ± 49.88 compared to 88.18 ± 0.85). Treatment with 17β-estradiol improved LVGP following HS.Conclusions: The results indicate that treatment with 17β-estradiol before resuscitation following HS protects the myocardium against dysfunction.