Morphine attenuates microvascular hyperpermeability via a protein kinase A-dependent pathway

Association of Opioid Administration During General Anesthesia and Survival for Severely Injured Trauma Patients: A Preplanned Secondary Analysis of the PROPPR Study

BACKGROUND

There is a lack of reported clinical outcomes after opioid use in acute trauma patients undergoing anesthesia. Data from the Pragmatic, Randomized, Optimal Platelet and Plasma Ratios (PROPPR) study were analyzed to examine opioid dose and mortality. We hypothesized that higher dose opioids during anesthesia were associated with lower mortality in severely injured patients.

METHODS

PROPPR examined blood component ratios in 680 bleeding trauma patients at 12 level 1 trauma centers in North America. Subjects undergoing anesthesia for an emergency procedure were identified, and opioid dose was calculated (morphine milligram equivalents [MMEs])/h. After separation of those who received no opioid (group 1), remaining subjects were divided into 4 groups of equal size with low to high opioid dose ranges. A generalized linear mixed model was used to assess impact of opioid dose on mortality (primary outcome, at 6 hours, 24 hours, and 30 days) and secondary morbidity outcomes, controlling for injury type, severity, and shock index as fixed effect factors and site as a random effect factor.

RESULTS

Of 680 subjects, 579 had an emergent procedure requiring anesthesia, and 526 had complete anesthesia data. Patients who received any opioid had lower mortality at 6 hours (odds ratios [ORs], 0.02-0.04; [confidence intervals {CIs}, 0.003-0.1]), 24 hours (ORs, 0.01-0.03; [CIs, 0.003-0.09]), and 30 days (ORs, 0.04-0.08; [CIs, 0.01-0.18]) compared to those who received none (all P < .001) after adjusting for fixed effect factors. The lower mortality at 30 days in any opioid dose group persisted after analysis of those patients who survived >24 hours (P < .001). Adjusted analyses demonstrated an association with higher ventilator-associated pneumonia (VAP) incidence in the lowest opioid dose group compared to no opioid (P = .02), and lung complications were lower in the third opioid dose group compared to no opioid in those surviving 24 hours (P = .03). There were no other consistent associations of opioid dose with other morbidity outcomes.

CONCLUSIONS

These results suggest that opioid administration during general anesthesia for severely injured patients is associated with improved survival, although the no-opioid group was more severely injured and hemodynamically unstable. Since this was a preplanned post hoc analysis and opioid dose not randomized, prospective studies are required. These findings from a large, multi-institutional study may be relevant to clinical practice.

Morphine-Induced Preconditioning: Involvement of Protein Kinase A and Mitochondrial Permeability Transition Pore

Background

Morphine induces myocardial preconditioning (M-PC) via activation of mitochondrial large conductance Ca²⁺-sensitive potassium (mK_Ca) channels. An upstream regulator of mK_Ca channels is protein kinase A (PKA). Furthermore, mK_Ca channel activation regulates mitochondrial bioenergetics and thereby prevents opening of the mitochondrial permeability transition pore (mPTP). Here, we investigated in the rat heart in vivo whether 1) M-PC is mediated by activation of PKA, and 2) pharmacological opening of the mPTP abolishes the cardioprotective effect of M-PC and 3) M-PC is critically dependent on STAT3 activation, which is located upstream of mPTP within the signalling pathway.

Methods

Male Wistar rats were randomised to six groups (each n = 6). All animals underwent 25 minutes of regional myocardial ischemia and 120 minutes of reperfusion. Control animals (Con) were not further treated. Morphine preconditioning was initiated by intravenous administration of 0.3 mg/kg morphine (M-PC). The PKA blocker H-89 (10 μg/kg) was investigated with and without morphine (H-89+M-PC, H-89). We determined the effect of mPTP opening with atractyloside (5 mg/kg) with and without morphine (Atr+M-PC, Atr). Furthermore, the effect of morphine on PKA activity was tested in isolated adult rat cardiomyocytes. In further experiments in isolated hearts we tested the protective properties of morphine in the presence of STAT3 inhibition, and whether pharmacological prevention of the mPTP-opening by cyclosporine A (CsA) is cardioprotective in the presence of STAT3 inhibition.

Results

Morphine reduced infarct size from 64±5% to 39±9% (P<0.05 vs. Con). H-89 completely blocked preconditioning by morphine (64±9%; P<0.05 vs. M-PC), but H-89 itself had not effect on infarct size (61±10%; P>0.05 vs. Con). Also, atractyloside abolished infarct size reduction of morphine completely (65±9%; P<0.05 vs. M-PC) but had no influence on infarct size itself (64±5%; P>0.05 vs. Con). In isolated hearts STAT3 inhibitor Stattic completely abolished morphine-induced preconditioning. Administration of Stattic and mPTP inhibitor cyclosporine A reduced infarct size to 31±6% (Stat+CsA, P<0.05 vs. Con). Cyclosporine A alone reduced infarct size to 26±7% (CsA P<0.05 vs. Con). In cardiomyocytes, PKA activity was increased by morphine.

Conclusion

Our data suggest that morphine-induced cardioprotection is mediated by STAT3-activation and inhibition of mPTP, with STA3 located upstream of mPTP. There is some evidence that protein kinase A is involved within the signalling pathway.

Protein kinase A mediates glucagon-like peptide 1-induced nitric oxide production and muscle microvascular recruitment

Glucagon-like peptide-1 (GLP-1) causes vasodilation and increases muscle glucose uptake independent of insulin. Recently, we have shown that GLP-1 recruits muscle microvasculature and increases muscle glucose use via a nitric oxide (NO)-dependent mechanism. Protein kinase A (PKA) is a major signaling intermediate downstream of GLP-1 receptors. To examine whether PKA mediates GLP-1's microvascular action in muscle, GLP-1 was infused to overnight-fasted male rats for 120 min in the presence or absence of H89, a PKA inhibitor. Hindleg muscle microvascular recruitment and glucose use were determined. GLP-1 infusion acutely increased muscle microvascular blood volume within 30 min without altering microvascular blood flow velocity or blood pressure. This effect persisted throughout the 120-min infusion period, leading to a significant increase in muscle microvascular blood flow. These changes were paralleled with an approximately twofold increase in plasma NO levels and hindleg glucose extraction. Systemic infusion of H89 completely blocked GLP-1-mediated muscle microvascular recruitment and increases in NO production and muscle glucose extraction. In cultured endothelial cells, GLP-1 acutely increased PKA activity and stimulated endothelial NO synthase phosphorylation at Ser(1177) and NO production. PKA inhibition abolished these effects. In ex vivo studies, perfusion of the distal saphenous artery with GLP-1 induced significant vasorelaxation that was also abolished by pretreatment of the vessels with PKA inhibitor H89. We conclude that GLP-1 recruits muscle microvasculature by expanding microvascular volume and increases glucose extraction in muscle via a PKA/NO-dependent pathway in the vascular endothelium. This may contribute to postprandial glycemic control and complication prevention in diabetes.

Endogenous opiates and behavior: 2008

This paper is the 31st consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2008 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).

Factors associated with anemia in patients with cancer admitted to an intensive care unit

PURPOSE

The study aimed to evaluate the relative impact of clinical and demographic factors associated with the prevalence and incidence of anemia (hemoglobin [Hb] <12 g/dL) in critically ill patients with cancer.

MATERIALS AND METHODS

We performed an electronic chart review for demographic and clinical data of adult patients with cancer with or without anemia admitted to the intensive care unit (ICU). Prevalence of anemia was determined at admission, and incidence determined if anemia developed during ICU stay. Anemia was classified as mild, moderate, or severe. The additive impact of clinical and demographic factors was evaluated by using a hierarchical linear regression model.

RESULTS

A total of 4705 patients were included in the study. The prevalence and incidence of anemia were 68.0% and 46.6%, respectively. In prevalent cases, we found that the clinical covariates modified sequential organ failure assessment score, admission to the medical ICU, prior chemotherapy, diagnosis of hematologic cancer, and length of hospital stay before ICU admission explained 18.7% of the variance in the model, whereas the demographic covariates (age, sex, and race) explained only an additional 0.6%. The pattern was similar for incidence cases.

CONCLUSIONS

Clinical factors are more influential than demographic factors in the observed rates of prevalence and incidence of anemia in the ICU; thus, protocols are needed to identify subgroups of patients with cancer who could benefit from novel management strategies.