Therapeutic Hypothermia Protects Against Heat Stroke-Induced Arterial Hypotension via Promoting Left Ventricular Performance in Rats

The pathogenesis and therapeutic strategies of heat stroke-induced myocardial injury

Heat stroke (HS) is a febrile illness characterized by an elevation in the core body temperature to over 40°C, accompanied by central nervous system impairment and subsequent multi-organ dysfunction syndrome. In recent years, the mortality rate from HS has been increasing as ambient temperatures continue to rise each year. The cardiovascular system plays an important role in the pathogenesis process of HS, as it functions as one of the key system for thermoregulation and its stability is associated with the severity of HS. Systemic inflammatory response and endothelial cell damage constitute pivotal attributes of HS, other factors such as ferroptosis, disturbances in myocardial metabolism and heat shock protein dysregulation are also involved in the damage to myocardial tissue in HS. In this review, a comprehensively detailed description of the pathogenesis of HS-induced myocardial injury is provided. The current treatment strategies and the promising therapeutic targets for HS are also discussed.

Xuebijing Injection Attenuates Heat Stroke-Induced Brain Injury through Oxidative Stress Blockage and Parthanatos Modulation via PARP-1/AIF Signaling

Heat stroke (HS) is a potentially fatal acute condition caused by an interplay of complex events including inflammation, endothelial injury, and coagulation abnormalities that make its pharmacological treatment a challenging problem. The traditional Chinese medicine Xuebijing injection (XBJ) has been shown to reduce inflammatory responses and prevent organ injuries in HS-induced mice. However, the underlying mechanism of XBJ in HS-induced brain injury remains unclear. In this study, HS-induced rat models and cell models were established to elucidate the effects and underlying mechanisms of XBJ injection on HS-induced brain injury in vivo and in vitro. The results revealed that XBJ injection improved the survival outcome of HS rats and attenuated HS-induced brain injury in a concentration-dependent manner. Subsequently, the reduction in viability and proliferation of neurons induced by HS were reversed by XBJ treatment, while the HS-induced increased ROS levels and neuron death were also inhibited by XBJ injection. Mechanistically, HS activated PARP-1/AIF signaling in vitro and in vivo, inducing the translocation of AIF from the cytoplasm to the nucleus, leading to PARP-1-dependent cell death of neurons. Additionally, we compared XBJ injection effects in young and old age rats. Results showed that XBJ also provided protective effects in HS-induced brain injury in aging rats; however, the treatment efficacy of XBJ injection at the same concentration was more significant in the young age rats. In conclusion, XBJ injection attenuates HS-induced brain injury by inhibiting oxidative stress and Parthanatos via the PARP-1/AIF signaling, which might provide a novel therapeutic strategy for HS treatment.

Myocardial structure and functional alterations in a preclinical model of exertional heat stroke

AIM

Relatively little information is available about the effect of an acute exertional heat stroke (EHS) on myocardium structure and function. Herein, we used a survival male rat model of EHS to answer the question.

MAIN METHODS

Adult male Wistar rats underwent forced treadmill running at a 36 °C room temperature and 50 % relative humidity until EHS onset, characterized by hyperthermia and collapse. All rats that were followed for 14 days survived. Injury severity scores of both gastrocnemius and myocardium were determined histologically. Following an EHS event, pathological echocardiography, skeletal muscle and myocardial damage scores and indicators, myocardial fibrosis, hypertrophy, and autophagy were elucidated.

KEY FINDINGS

Rats with EHS onset displayed skeletal muscle damage, elevated serum levels of skeletal muscle indicators (e.g., creatinine kinase, myoglobin, and potassium) and myocardial injury indicators (e.g., cardiac troponin I, creatinine kinase, and lactate dehydrogenase) returning to homeostasis within 3 days post-EHS. However, EHS-induced myocardial damage, pathological echocardiography, myocardial fibrosis, hypertrophy, and deposited misfolded proteins lasted up to 14 days post-EHS at least.

SIGNIFICANCE

First, we provide evidence to confirm that despite the apparent return to homeostasis, underlying processes may still be ongoing after EHS onset. Second, we provide several key findings emphasizing the pathophysiology and risk factors of EHS, highlighting gaps in knowledge with the aim of stimulating future studies.

Clinical characteristics and risk factors of male exertional heatstroke in patients with myocardial injury: an over 10-year retrospective cohort study

BACKGROUND

Heatstrokes are a serious threat to human health, particularly the cardiovascular system. Understanding the clinical features and risk factors related to death in patients with myocardial injury (MI) complicated by heat stroke is crucial.

METHOD

This study included the baseline data of all patients with severe heatstroke between October 2008 and May 2019.

RESULTS

Of the 162 patients enrolled, 75 (46.3%) were in the MI group and 87 (53.7%) were in the non-MI group. A significant difference was noted in 90-day survival between the two groups even after correction for Age, Acute Physiology, and Chronic Health Evaluation II (APACHE II) scores, Sequential Organ Failure Assessment (SOFA) scores, Glasgow Coma Score (GCS), and activated partial thromboplastin time (before correction (p < .001; after correction, p = .023). Survival analysis showed that the 90-day survival time of patients with MI was shorter than that of patients without MI (p < .001). The area under the receiver operating characteristic (ROC) curve for predicting mortality based on the SOFA score was 92.8% (95% CI 0.847-1.000, p < .001), the optimal cutoff value was 7.5, the sensitivity was 91.7%, and the specificity was 94.6%.

CONCLUSION

Patients with heatstroke having MI had more severe clinical conditions, 90-day mortality was significantly increased, and the survival time was shortened. A high SOFA score is an independent risk factor for death in patients with heatstroke having MI, with an optimal cutoff value of 7.5, sensitivity of 91.7%, and specificity of 94.6%.