Vivian Wolfe

The AMPK Activator Aicar Ameliorates Age-Dependent Myocardial Injury in Murine Hemorrhagic Shock.

ABSTRACT The development of myocardial dysfunction in patients with hemorrhagic shock is significantly impacted by the patient age. AMP-activated protein kinase (AMPK) is a pivotal orchestrator of energy homeostasis, which coordinates metabolic recovery after cellular stress. We investigated whether AMPK-regulated pathways are age-dependent in hemorrhage-induced myocardial injury and whether AMPK activation by 5-amino-4-imidazolecarboxamide riboside (AICAR) affords cardioprotective effects. Anesthetized C57/BL6 young (3–5 months old) and mature (9–12 months old) male mice were subjected to hemorrhagic shock by blood withdrawing followed by resuscitation with shed blood and Lactated Ringers solution. Mice were sacrificed at 3 h after resuscitation, and plasma and hearts were harvested for biochemical assays. Vehicle-treated mature mice exhibited higher myocardial injury and higher levels of plasma biomarkers of cardiovascular injury (endocan and follistatin) when compared with young mice. Cardiac cell mitochondrial structure was also markedly impaired in vehicle-treated mature mice when compared with young mice. At molecular analysis, an increase of the phosphorylated catalytic subunit pAMPK&agr; was associated with nuclear translocation of the peroxisome proliferator-activated receptor &ggr; coactivator-&agr; in young, but not mature mice. No changes in autophagy were observed as evaluated by the conversion of the light-chain (LC)3B-I protein to LC3B-II form. Treatment with AICAR ameliorated myocardial damage in both age groups. However, AICAR therapeutic effects were less effective in mature mice than young mice and involved distinct mechanisms of action. Thus, our data demonstrate that during hemorrhagic shock AMPK-dependent metabolic mechanisms are important for mitigating myocardial injury. However, these mechanisms are less competent with age.

Age-Dependent Changes in AMPK Metabolic Pathways in the Lung in a Mouse Model of Hemorrhagic Shock

&NA; The development of multiple organ failure in patients with hemorrhagic shock is significantly influenced by patient age. Adenosine monophosphate‐activated protein kinase (AMPK) is a crucial regulator of energy homeostasis, which coordinates metabolic repair during cellular stress. We investigated whether AMPK‐regulated signaling pathways are age‐dependent in hemorrhage‐induced lung injury and whether AMPK activation by 5‐amino‐4‐imidazole carboxamide riboside (AICAR) affords lung protective effects. Male C57/BL6 young mice (3‐5 mo), mature adult mice (9‐12 mo), and young AMPK&agr;1 knockout mice (3‐5 mo) were subjected to hemorrhagic shock by blood withdrawing, followed by resuscitation with shed blood and lactated Ringers solution. Plasma proinflammatory cytokines were similarly elevated in C57/BL6 young and mature adult mice after hemorrhagic shock. However, mature adult mice exhibited more severe lung edema and neutrophil infiltration, and higher mitochondrial damage in alveolar epithelial type II cells, than did young mice. No change in autophagy was observed. At molecular analysis, the phosphorylation of the catalytic subunit AMPK&agr;1 was associated with nuclear translocation of peroxisome proliferator‐activated receptor &ggr; co‐activator‐&agr; in young, but not mature, adult mice. Treatment with AICAR ameliorated the disruption of lung architecture in mice of both ages; however, effects in mature adult mice were different than young mice and also involved inhibition of nuclear factor‐&kgr;B. In young AMPK&agr;1 knockout mice, AICAR failed to improve hypotension and lung neutrophil infiltration. Our data demonstrate that during hemorrhagic shock, AMPK‐dependent metabolic repair mechanisms are important for mitigating lung injury. However, these mechanisms are less competent with age.

Metformin ameliorates gender-and age-dependent hemodynamic instability and myocardial injury in murine hemorrhagic shock

Severity of multiple organ failure is significantly impacted by age and gender in patients with hemorrhagic shock. However, the molecular mechanisms underlying the enhanced organ injury are not fully understood. AMP-activated protein kinase (AMPK) is a pivotal orchestrator of metabolic responses during stress. We investigated whether hemorrhage-induced myocardial injury is age and gender dependent and whether treatment with metformin, an AMPK activator, affords cardioprotective effects. C57/BL6 young (3-5months) and mature (9-12months) male and female mice were subjected to hemorrhagic shock by blood withdrawing followed by resuscitation with blood and Lactated Ringers solution. Vehicle-treated young and mature mice of both genders had a similar elevation of plasma inflammatory cytokines at 3h after resuscitation. However, vehicle-treated male mature mice experienced hemodynamic instability and higher myocardial damage than young male mice, as evaluated by echocardiography, histology and cardiovascular injury biomarkers. There was also a gender-dependent difference in cardiovascular injury in the mature group as vehicle-treated male mice exhibited more severe organ injury than female mice. At molecular analysis, vehicle-treated mature mice of both genders exhibited a marked downregulation of AMPKα activation and nuclear translocation of peroxisome proliferator-activated receptor γ co-activator α when compared with young mice. Treatment with metformin improved cardiovascular function and survival in mature animals of both genders. However, specific cardioprotective effects of metformin were gender-dependent. Metformin did not affect hemodynamic or inflammatory responses in young animals. Thus, our data suggest that targeting metabolic recovery with metformin may be a potential treatment approach in severe hemorrhage in adult population.

126: AGE-DEPENDENT CHANGES OF AMPK-ACTIVATED PATHWAY IN THE HEART FOLLOWING HEMORRHAGIC SHOCK IN MICE

Crit Care Med 2015 • Volume 43 • Number 12 (Suppl.) recognize relevant clinical variables associated with FO, we assessed the epidemiology of FO after CPB in our institution. Methods: We performed a single center, prospective, observational pilot study in children aged 0 to 18 yr undergoing CPB from June to July 2015. We excluded subjects with existing renal and hepatic impairment, coagulopathy and prematurity. The primary outcome was peak %FO ([Postoperative weight (kg) – Daily weight (kg)]/preoperative weight (kg) x 100%). Extensive descriptive data including anthropometrics, surgical data and postoperative course were obtained. A FO ≥10% cohort was compared to a FO <10% cohort using unadjusted, two-tailed Wilcoxon rank-sum tests and student t tests for continuous data and Fisher’s exact test for categorical data. Results: 21 patients were enrolled during the study period. Median age was 32 mo (interquartile range 9–102) with seven (33%) patients identified with cyanotic heart disease. No patient required dialysis or died during admission. Peak FO was noted on post-operative day 2 with a mean of 9.1% (+/12.5%). Thirteen (62%) patients had FO <10% and eight (38%) had FO ≥10%. The two cohorts did not differ in risk stratification or incidence of postoperative acute kidney injury. The FO ≥10% cohort had longer CPB times (117 vs. 69 min, p=0.03), cross clamp times (63 vs. 31 min, p=0.04) and higher vasoactive-inotropic scores (8 vs. 3, p=0.04). The FO ≥10% cohort were younger (7 vs. 50 mo, p=0.05). Conclusions: These data from our single center pilot suggest a moderately high prevalence of FO in children after CPB. The degree of FO appears correlated to surgical duration and inversely to age. These data will allow the stratification and validation of planned biomarker research.