Nitric oxide synthesis in myocardium following burn injury in rats

Trauma, a Matter of the Heart-Molecular Mechanism of Post-Traumatic Cardiac Dysfunction

Trauma remains a leading global cause of mortality, particularly in the young population. In the United States, approximately 30,000 patients with blunt cardiac trauma were recorded annually. Cardiac damage is a predictor for poor outcome after multiple trauma, with a poor prognosis and prolonged in-hospitalization. Systemic elevation of cardiac troponins was correlated with survival, injury severity score, and catecholamine consumption of patients after multiple trauma. The clinical features of the so-called "commotio cordis" are dysrhythmias, including ventricular fibrillation and sudden cardiac arrest as well as wall motion disorders. In trauma patients with inappropriate hypotension and inadequate response to fluid resuscitation, cardiac injury should be considered. Therefore, a combination of echocardiography (ECG) measurements, echocardiography, and systemic appearance of cardiomyocyte damage markers such as troponin appears to be an appropriate diagnostic approach to detect cardiac dysfunction after trauma. However, the mechanisms of post-traumatic cardiac dysfunction are still actively being investigated. This review aims to discuss cardiac damage following trauma, focusing on mechanisms of post-traumatic cardiac dysfunction associated with inflammation and complement activation. Herein, a causal relationship of cardiac dysfunction to traumatic brain injury, blunt chest trauma, multiple trauma, burn injury, psychosocial stress, fracture, and hemorrhagic shock are illustrated and therapeutic options are discussed.

Pathological Responses of Cardiac Mitochondria to Burn Trauma

Despite advances in treatment and care, burn trauma remains the fourth most common type of traumatic injury. Burn-induced cardiac failure is a key factor for patient mortality, especially during the initial post-burn period (the first 24 to 48 h). Mitochondria, among the most important subcellular organelles in cardiomyocytes, are a central player in determining the severity of myocardial damage. Defects in mitochondrial function and structure are involved in pathogenesis of numerous myocardial injuries and cardiovascular diseases. In this article, we comprehensively review the current findings on cardiac mitochondrial pathological changes and summarize burn-impaired mitochondrial respiration capacity and energy supply, induced mitochondrial oxidative stress, and increased cell death. The molecular mechanisms underlying these alterations are discussed, along with the possible influence of other biological variables. We hope this review will provide useful information to explore potential therapeutic approaches that target mitochondria for cardiac protection following burn injury.

Cardiovascular Dysfunction Following Burn Injury: What We Have Learned from Rat and Mouse Models

Severe burn profoundly affects organs both proximal and distal to the actual burn site. Cardiovascular dysfunction is a well-documented phenomenon that increases morbidity and mortality following a massive thermal trauma. Beginning immediately post-burn, during the ebb phase, cardiac function is severely depressed. By 48 h post-injury, cardiac function rebounds and the post-burn myocardium becomes tachycardic and hyperinflammatory. While current clinical trials are investigating a variety of drugs targeted at reducing aspects of the post-burn hypermetabolic response such as heart rate and cardiac work, there is still a paucity of knowledge regarding the underlying mechanisms that induce cardiac dysfunction in the severely burned. There are many animal models of burn injury, from rodents, to sheep or swine, but the majority of burn related cardiovascular investigations have occurred in rat and mouse models. This literature review consolidates the data supporting the prevalent role that β-adrenergic receptors play in mediating post-burn cardiac dysfunction and the idea that pharmacological modulation of this receptor family is a viable therapeutic target for resolving burn-induced cardiac deficits.

Inhibition of p38 MAP kinase improves survival of cardiac myocytes with hypoxia and burn serum challenge

This study was aimed to investigate the effects of SB203580, the specific p38 mitogen-activated protein (MAP) kinase inhibitor, on cardiac myocyte survival and secretion of cytokines in an in vitro model of hypoxia and burn serum challenge. Results demonstrated that hypoxia and burn serum induced a persistent activation of p38 MAP kinase in primary cultured neonatal rat cardiomyocytes during the 12h period of stimulation, concomitant with a time-dependent increased expression of tumor necrosis factor (TNF)-alpha and inducible nitric oxide (iNOS), a progressively developed oxidative stress reflected by malondialdehyde (MDA) production, and myocytes injury evidenced by the increased levels of released lactate dehydrogenase (LDH) and the decreased myocyte viability. Furthermore, hypoxia and burn serum resulted in a significant increase in myocyte apoptosis, which may account for the impairment of myocyte viability as observed. SB203580 abolished p38 MAP kinase activation, blunted the upregulation of TNF-alpha, iNOS and the subsequent nitric oxide (NO) production, reduced oxidative stress, and alleviated hypoxia and burn serum-induced myocytes injury or apoptosis. These results demonstrated for the first time that inhibition of p38 MAP kinase improves survival of cardiac myocytes with hypoxia and burn serum challenge possibly via reducing the production of cytokines, such as TNF-alpha and NO, and the subsequent oxidative stress, providing strong evidence that the excessive inflammatory cytokines produced by cardiomyocytes themselves may be sufficient to cause myocardial injury after burn.

Local and systemic expression of inducible nitric oxide synthase in comparison with that of cyclooxygenase-2 in rat carrageenin-induced pleurisy

Expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) is up-regulated in response to inflammatory stimuli. To evaluate the extent to which local pleural inflammation involves additional site in the pleural cavity and elsewhere, we investigated the time course of the levels of iNOS and its product in the inflammatory and other sites, and compared those with a level of COX-2 in rat carrageenin-induced pleurisy. The exudate and plasma NOx levels rose, reaching peaks at 9 and 14 h, respectively. Both COX-2 and iNOS became detectable in exudate leukocytes, their levels reaching peaks at 3 and 9 h after irritation, respectively. COX-2 was detectable mainly in neutrophils, but iNOS was detectable in both neutrophils and mononuclear leukocytes. Furthermore, iNOS became detectable in neutrophils and mononuclear leukocytes in enlarged parathymic lymph nodes from 3h in addition to those in peripheral blood and Kupffer cells from 3 to 14 h, respectively. The gene product is also detectable in thymic large dendritic cells of pleurisy-induced rats as well as normal control rats. COX-2 became detectable in stellar dendritic cells of the enlarged draining lymph nodes from 14 h. Thus, these gene products were induced in the immediate proximity of regional lymph nodes, and even at a considerable distance of liver by the local inflammatory stimulus. Although their expression pattern was quite different from each other, these gene products were detectable in phagocytic cells.

Role of Thymus Oil in Burn Wound Healing

Thymus oil and its components are becoming increasingly popular as naturally occurring antimicrobial and antioxidant agents. The real importance of thymus on nitric oxide (NO) is unknown. NO is an important mediator in numerous physiologic and pathophysiologic events. Stasis and thrombosis in burn wound can progress as a result of the release of local mediators. The implication of NO in burn injury is not well studied. In this study, we tried to determine the role of burn-induced NO and whether thymus oil plays a protective role after a thermal injury. Rats were divided into five groups. We topically applied thymus oil, olive oil, and silverdin and sulfadiazine on the rats, respectively, during a period of 21 days after they were burned while under anesthesia. The burned control group and nonburned control group did not receive any treatment. The results of this study show that NO was overproduced by thermal injury and decreased during the days after burn injury. The decrease in rats treated with thymus and sulfadiazine was higher than the others. These data indicate that thymus oil may serve as a protective agent to the damaged tissues by decreasing the NO level. Histologic examination results show that the formation of new tissue in rats receiving thymus oil was more than other burned groups, and this finding supports our hypothesis.

Nitric oxide, inflammation and acute burn injury

Nitric oxide (NOz.rad;) is a diatomic mediator liberated on oxidation of L-arginine by the nitric oxide synthase (NOS) family of enzymes. It has complex and wide ranging functions in vivo and has been implicated in the development of the profound inflammatory response that occurs as a result of cutaneous burn injury. In addition, dysregulation of NOS activity has been associated with multiple organ failure in human burn patients and may therefore represent a novel therapeutic target in such circumstances. This review focuses on the role of NOz.rad; in inflammation, with particular emphasis on the acute post-burn inflammatory response. Specific areas of discussion include the maintenance of microvascular haemostasis, leukocyte recruitment and remote organ dysfunction following thermal injury.

Effects of a thermal injury on brain and blood nitric oxide (NO) content in the rat

In the present study, the effects of a thermal injury on the nitric oxide (NO)-ergic system was investigated in freely moving rats. Using a voltammetric method allowing direct and in situ NO measurements, a significant decrease in cortical NO concentration was observed during the 24h following burning procedure. Since in the burning procedure halothane was employed, it was verified that this anaesthetic did not induce significant effect on cortical NO level. Experiments conducted in ex vivo conditions showed that blood NO and nitrites (NO(2)(-)) + nitrates (NO(3)(-)) concentrations increased strongly after burn injury while hypothalamic inducible NO-synthase (NOS(2)) mRNA level decreased significantly. A thermal injury was thus accompanied by a rapid impairment of the NO-ergic pathways, which might partly have been responsible for numerous changes occurring after burn injury.