Introduction: The detrimental effects of epinephrine are closely related to its β- and a1- action, which significantly increases the severity of post-resuscitation (PR) myocardial dysfunction. In the present study, we investigated the effects of β- and β- plus α1- adrenergic blocking agents on post-resuscitation myocardial dysfunction and myocardial injury biomarkers. Methods: Twenty-four male Sprague-Dawley rats weighing between 450 - 550g were randomized into 4 groups: 1) placebo; 2) epinephrine; 3) epinephrine with β- blocker (propranolol) and; 4) epinephrine with β- plus α1- blockers (propranolol and prazosin). Ventricular fibrillation (VF) was electrically induced. CPR was initiated after 8 mins of untreated VF and continued for 8 mins. Defibrillation was then attempted. Ejection fraction (EF) and myocardial performance index (MPI) were measured at baseline and at hourly intervals for 4 hrs after resuscitation. Troponin I (Tn I) and N-terminal pro-brain natriuretic peptide (NT-pro BNP) were measured at baseline and at 1 and 4 hrs after resuscitation by the ELISA kits. Results: The β- and β- plus α1- blockers significantly reduced the severity of PR myocardial dysfunction. EF and MPI were 60.23 ± 1.23 and 1.01 ± 0.06 in the β- blocker group and 63.63 ± 1.51 and 0.89 ± 0.03 in the β- plus α1- blockers treated group compared to 39.90 ± 2.60 and 1.34 ± 0.10 in the epinephrine treated group and 44.58 ± 4.57 and 1.25 ± 0.10 in the placebo group at PR 4 hrs (p<0.05). The β- and β- plus α1- blockers pretreatment also reduced the releases of Tn I and NT-pro BNP compared with the placebo and epinephrine groups at PR 4 hrs (2.4 ± 1.0 and 1.8 ± 0.6 vs. 8.2 ± 5.2 and 9.5 ± 6.9 ng/L, p<0.05; 153.7 ± 44.9 and 151.7 ± 24.3 vs. 241.8 ± 16.9 and 298.9 ± 118.5 ng/L, p<0.05). The β- and β- plus α1-blockers significantly improved the duration of survival (67.8 ± 10.2 and 72.0 ± 0 vs. 34.4 ± 34.6 and 22.8 ± 26.4 hrs, p<0.05). Conclusions: The β- and β- plus α1-blockers reduced the severity of PR myocardial dysfunction and attenuated release of myocardial injury biomarkers with improved duration of survival in a rat model of CPR.
1Weil Institute of Critical Care Medicine, rancho mirage, CA, 2the Second Hospital of Anhui Medical University, P.R China, Hefei, Anhui, China, 3the Weil Institute of Critical Care Medicine, rancho mirage, CA, 4Weil Institute of Critical Care Medicine, Rancho Mirage, CA, 5he Weil Institute of Critical Care Medicine, rancho mirage, CA