Changes in renal sympathetic nerve activity during experimental septic and endotoxin shock in conscious rats

Changes in postganglionic renal sympathetic nerve activity, arterial pressure, and heart rate were measured in conscious rats during intravenous infusion of live E. coli bacteria (10(9)/h) or bolus injection of E. coli endotoxin (20 mg/kg). Bacteria infusion was associated with a marked and parallel increase in heart rate and sympathetic activity with only minor changes in mean arterial pressure. The early response to bolus injection of endotoxin was a short-lasting decrease in mean arterial pressure combined with a marked increase in sympathetic activity and heart rate, probably due to baroreceptor unloading. However, when mean arterial pressure returned to pre-endotoxin levels, sympathetic activity and heart rate remained markedly elevated, indicating a partly nonreflexogenic increase in central sympathetic outflow. This study using direct nerve recordings of sympathetic activity in conscious animals confirms earlier clinical observations of an increased activity of the sympathetic nervous system in septic shock.     

Changes in central hemodynamics during experimental septic shock in conscious rats

This study describes the hemodynamic, metabolic, and respiratory effects of a 4-h continuous intravenous infusion of live Escherichia coli bacteria (10(9)/h) in conscious, unrestrained rats. The early response to bacterial infusion was moderate hypotension and a marked and sustained increase in heart rate and respiratory rate. During later stages of bacteria infusion a marked decrease in stroke volume and cardiac output was observed, while total peripheral resistance increased. Arterial blood gas measurements showed an early primary respiratory alkalosis, while later stages of bacteria infusion were accompanied by progressive development of metabolic acidosis. This small-sized animal shock model may be useful for further studies, particularly since conscious rats were used to avoid the influence of anesthesia upon the development of septic shock.     

门静脉高压大鼠内源性硫化氢体系的变化

在肝硬化门静脉高压形成中，门静脉系统的血流量增加是门静脉高压产生和加重的重要因素之一，近几年来人们发现气体信号分子NO、CO可以引起内脏血管扩张而使门静脉系统血流量增加。最近的研究发现H2S具有与NO、CO相似的生物学效应，如舒张血管、抑制平滑肌细胞增殖等。内源性H2S在诸多心血管疾病的发病过程中发挥着重要的病理生理学作用，广泛参与低氧性肺动脉高压、肺动脉高压、高血压、感染性休克等心肺疾病的发病过程。在门静脉高压的发病过程中是否也有H2S的参与，目前国内外鲜见报道。本研究以部分门静脉结扎大鼠为对象，观察门静脉高压大鼠门静脉压力的变化以及CSE基因表达的改变，以探讨H2S在门静脉高压中的作用。     

Changes in canine leukocyte glucocorticoid receptors during endotoxin shock

We studied changes in canine leukocyte glucocorticoid receptors during endotoxin shock. Blood samples for analysis were collected and leukocytes were isolated just prior to and 2 and 6 hours after endotoxin administration. Employing 3H-dexamethasone (3H-Dex) as a ligand, we studied 3H-Dex-specific binding of the leukocytes in dogs and their changes during endotoxin shock. Results from two groups (anesthetized and conscious) showed that the specific binding of the leukocytes decreased significantly 2 hours after endotoxin administration in both groups and 6 hours after endotoxin in anesthetized dogs. In conscious dogs, the specific binding returned to normal by 6 hours. No correlation was found between the changes of serum cortisol and 3H-Dex-specific binding. It may be suggested that perturbations in glucocorticoid hormone action at the receptor level might be involved in the pathogenesis of endotoxin shock.     

Oxygen delivery and utilization during rapidly fatal septic shock in rats

Oxygen delivery and utilization were studied in a rapidly fatal model of rat peritonitis. Cecal ligation and perforation induced peritonitis and septic shock in five animals. Five animals served as sham-operated controls. Arterial pressure, central venous pressure, cardiac index, hemoglobin, plasma colloid osmotic pressure, arterial blood lactate concentration, and arterial and central venous oxygen saturation were sequentially measured over 5 hr. In septic animals, decreases in mean central venous pressure were associated with hemoconcentration and decreases in plasma colloid osmotic pressure from 16.3 +/- 0.8 to 12.2 +/- 0.1 mmHg (P less than 0.05). The cardiac index decreased from 359 +/- 35 to 166 +/- 25 ml/kg/min (P less than 0.001), and arterial lactate increased from 0.2 +/- 0.1 to 2.1 +/- 0.4 mmol (P less than 0.001). However, oxygen consumption was maintained secondary to increases in systemic oxygen extraction. Arterial lactate concentration was inversely correlated with systemic oxygen delivery and central venous oxygen saturation (r = -0.68, P less than 0.05 and r = -0.71, P less than 0.001, respectively). These observations during lethal peritonitis suggest that hypovolemia is associated with increases in microvascular permeability, although the concomitant influence of intravascular pooling cannot be excluded. Decreases in systemic perfusion appear to account for critical oxygen deficits and lactic acidosis. The increases in systemic oxygen extraction imply that cellular oxygen utilization is maintained during lethal septic shock.     

Hydrogen sulfide (H2S) metabolism in mitochondria and its regulatory role in energy production

Although many types of ancient bacteria and archea rely on hydrogen sulfide (H(2)S) for their energy production, eukaryotes generate ATP in an oxygen-dependent fashion. We hypothesize that endogenous H(2)S remains a regulator of energy production in mammalian cells under stress conditions, which enables the body to cope with energy demand when oxygen supply is insufficient. Cystathionine γ-lyase (CSE) is a major H(2)S-producing enzyme in the cardiovascular system that uses cysteine as the main substrate. Here we show that CSE is localized only in the cytosol, not in mitochondria, of vascular smooth-muscle cells (SMCs) under resting conditions, revealed by Western blot analysis and confocal microscopy of SMCs transfected with GFP-tagged CSE plasmid. After SMCs were exposed to A23187, thapsigargin, or tunicamycin, intracellular calcium level was increased, and CSE translocated from the cytosol to mitochondria. CSE was coimmunoprecipitated with translocase of the outer membrane 20 (Tom20) in mitochondrial membrane. Tom20 siRNA significantly inhibited mitochondrial translocation of CSE and mitochondrial H(2)S production. The cysteine level inside mitochondria is approximately three times that in the cytosol. Translocation of CSE to mitochondria metabolized cysteine, produced H(2)S inside mitochondria, and increased ATP production. Inhibition of CSE activity reversed A23187-stimulated mitochondrial ATP production. H(2)S improved mitochondrial ATP production in SMCs with hypoxia, which alone decreased ATP production. These results suggest that translocation of CSE to mitochondria on specific stress stimulations is a unique mechanism to promote H(2)S production inside mitochondria, which subsequently sustains mitochondrial ATP production under hypoxic conditions.     

Dramatic changes in blood gases that are unrelated to arterial pH or cerebral oxygen delivery during endotoxin shock in conscious rats

In preliminary studies we demonstrated an effect of endotoxin on arterial blood gases that appeared to be related to the dose of endotoxin used and unrelated to changes in arterial pH. In the present study we tested the hypothesis that these changes in blood gases result from decreased oxygen delivery to central respiratory control areas. PO2 significantly rose from a pre-endotoxin value of 91.4 +/- 1.5 (mean +/- SEM) to 97.5 +/- 1.7, 104.0 +/- 0.8, and 108.4 +/- 0.9 at 10, 30, and 60 minutes, respectively, after administration of 6 mg/kg endotoxin and from 93.8 +/- 3.1 to 105.2 +/- 2.6, 118.7 +/- 1.4, and 121.0 +/- 2.8, respectively, after administration of 10 mg/kg endotoxin. PCO2 fell significantly from a pre-endotoxin value of 38.3 +/- 1.2 to 28.6 +/- 0.6 and 24.5 +/- 1.9 at 30 and 60 minutes post-endotoxin, respectively, in 6-mg/kg-treated rats, and from 40.5 +/- 2.1 to 30.7 +/- 4.5, 20.1 +/- 3.9, and 19.3 +/- 1.0, respectively, at 10, 30, and 60 minutes post-10 mg/kg endotoxin. The only significant change (decrease) in pH occurred at 60 minutes after 10 mg/kg treatment. In 10-mg/kg-treated rats, serum lactate rose significantly over time, while HCO-3 decreased. Heart rate was increased significantly (472 +/- 9.6) from a pre-10 mg/kg endotoxin value of 373 +/- 11.8 by 10 minutes post-endotoxin and remained elevated throughout the experiment. Cerebral medullary/pontine blood flow, mean arterial blood pressure, and respiratory rate were not significantly altered by endotoxin administration. Hemoglobin concentration and arterial oxygen content were significantly increased after 10 mg/kg endotoxin. These findings indicate that decreased oxygen delivery to central respiratory control areas is not a cause of the observed dramatic changes in blood gases.     

全脑缺血-再灌注大鼠脑组织内源性硫化氢的动态变化

目的探讨大鼠全脑缺血-再灌注过程中,不同时点内源性硫化氢（H2S）含量、胱硫醚β合酶（cystathionine beta synthase,CBS）活性及其mRNA表达的变化。方法取雄性SD大鼠56只,随机分为正常组、假手术组和脑缺血-再灌注（cerebral ischemia-reperfusion;I/R）12、24、48、72h及7d组,每组8只大鼠。应用四血管阻断法制作大鼠全脑I/R模型。采用全自动酶标仪（Bio-TEK ELx800,美国）测定各组大鼠双侧前脑皮质中H2S含量、CBS活性;用逆转录聚合酶链反应（RT-PCR）检测CBS mRNA表达的变化。结果正常组和假手术组大鼠前脑皮质组织H2S含量分别为（12.5±1.3）和（11.7±1.4）nmol/g,CBS酶活性分别为（44.5±2.3）和（44.1±2.8）nmol·g^-1·h^-1,CBS mRNA灰度值为3.62±0.23和3.94±0.40,两组比较差异无统计学意义（P〉0.05）。I/R12h组H2S含量为（18.3±1.2）nmol/g,CBS酶活性为（66.7±3.1）nmol·g^-1·h^-1,CBS mRNA灰度值为7.20±1.25;与假手术组比较均增高,差异均有统计学意义（P〈0.01）。I/R24h组以上指标为（8.3±1）nmol/g、（30.8±3.5）nmol·g^-1·h^-1及0.90±0.16,与假手术组比较均降低,差异均有统计学意义（P〈0.01）。I/R48、72h组以上指标逐渐恢复正常水平,与假手术组比较差异无统计学意义（P〉0.05）。I/R7d组CBS mRNA灰度值为5.19±0.01,与假手术组比较差异有统计学意义（P〈0.01）,其余指标差异均无统计学意义。结论内源性H2S在全脑缺血-再灌注的发生、发展过程中呈动态变化,并可能在缺血-再灌注早期发挥作用。     

Drotrecogin alpha (activated) in neonatal septic shock

A 12-d-old neonate suffering from group B streptococcal septic shock was treated with 24 microg/kg/h recombinant human activated protein C [rhAPC, drotrecogin alpha (activated)] for 96 h. The protein C activity increased from 5% to 53% after rhAPC infusion. The patient recovered within 14 d without any adverse effects.     

Circulating interleukin-1 and tumor necrosis factor in septic shock and experimental endotoxin fever

Interleukins (IL) -1 beta and -1 alpha and tumor necrosis factor (TNF-alpha) were measured by radioimmunoassay in plasma samples from 44 healthy individuals, 15 patients in septic shock, and 6 volunteers infused with endotoxin. Plasma IL-1 alpha levels were low (40 pg/ml) or undetectable in all situations. In 67% of the healthy subjects, plasma IL-1 beta levels were less than 70 pg/ml. Septic patients had higher plasma IL-1 beta levels (120 +/- 17 pg/ml, P = .001); those of surviving patients were higher than those of patients who died (P = .05). Plasma TNF-alpha concentrations in septic individuals were elevated (119 +/- 30 pg/ml) and correlated with severity of illness (r = .73, P = .003), but no correlation was observed between plasma IL-1 beta and TNF-alpha concentrations in individual samples. Infusion of endotoxin caused a twofold elevation of IL-1 beta, from a baseline of 35 +/- 5 pg/ml to a maximum of 69 +/- 27 pg/ml at 180 min (P less than .05). Peak TNF-alpha levels after endotoxin infusion were 15 times higher than IL-1 beta levels, were attained more rapidly (90 min), and as with the septic patients, did not correlate with IL-1 beta levels. These data support the concept that plasma IL-1 beta and TNF-alpha concentrations are regulated independently and are associated with different clinical outcomes.     

Changes of neurotensin and endotoxin in rats with intestinal ischemia

AIM: To investigate the changes of neurotensin (NT) and endotoxin in rats with segmental intestinal ischemia. METHODS: The distal ileal mesenteric arteries in rats were ligated to make segmental intestinal ischemia models. At the 2^nd, 6^th and 12^th hours after intestinal ischemia, endotoxin levels in portal blood were tested by limulus lysate test and NT levels in plasma from the heart and in intestine tissues (ischemia and peri-ischemia areas) were assayed by radioimmunoassay. Histological changes of the mucosa were examined under light and electron microscopes. RESULTS: NT levels decreased significantly in intestinal ischemia and peri-ischemia areas (34.07 ± 5.93 vs 40.14 ± 5.38, P < 0.05; 7.47 ± 1.38 vs 40.14 ± 5.38, P < 0.01), especially lower in ischemia area (34.07 ± 5.93 vs 7.47 ± 1.38, P < 0.05. However, NT level increased obviously in plasma (0.76 ± 0.16 vs 0.47 ± 0.10, P < 0.05). Levels of endotoxin elevated obviously in portal blood (389.0 ± 105.0 vs 55.1 ± 6.7, P < 0.01), and the mucosa was injured both in ischemia and peri-ischemia areas. CONCLUSION: Intestinal ischemia injures intestinal mucosa and leads to decrease of intestinal NT level, which is accelerated by endotoxemia and increase of blood NT level.     

Changes in anti-endotoxin-IgG antibody and endotoxaemia in three cases of gram-negative septic shock

Circulating endotoxin levels and IgG antibodies to a range of Gram-negative bacterial lipopolysaccharides (LPS) (endotoxins) of different sizes and structures were measured daily in three cases of septic shock. There was an inverse relationship between endotoxin levels and cross-reactive antibodies to the core glycolipid (CGL) region of lipopolysaccharide. This suggests that antibody to LPS-CGL was initially consumed by a superabundance of endotoxin, and that a resurgence of intrinsic anti-LPS-CGL antibody levels may be associated with a reduction of circulating endotoxin. The implications of these findings for passive antibody therapy of septic shock are discussed.     

感染性休克患者降钙素原和C-反应蛋白动态变化研究

目的观察降钙素原(PCT)、C-反应蛋白(CRP)等指标在感染性休克患者中的动态变化和急性生理和慢性健康(APACHEⅡ)评分在预后评估中的作用。方法回顾性分析45例感染性休克患者入院第1、3、5天以及出院或死亡前最后一次的血清PCT、CRP及入院时APACHEⅡ评分,根据预后将患者分为死亡组及存活组,并对其进行分析。结果 45例感染性休克患者生存20例,死亡25例,病死率为55.6%。死亡组患者入院时APACHEⅡ评分明显高于存活组[(28.84±8.03)分vs(21.82±7.10)分]。两组在入组第1、3天的PCT和CRP水平比较差异均无统计学意义。死亡组PCT和CRP水平在第5天及观察终点均明显高于存活组。各组内PCT和CRP与观察第1天相比,存活组随观察时间延长而明显下降,差异有统计学意义,而死亡组则无明显变化。结论患者血清中PCT、CRP呈持续高水平提示预后不佳,指标的高低对临床指导治疗和评估预后有参考意义。     

Effects of 2-[(5-chloro-2-methoxyphenyl)azo]-1H-imidazole (M6434) on hemorrhagic, cardiogenic, and endotoxin shock in rats and rabbits

The effects of 2-[(5-chloro-2-methoxyphenyl)azo]-1H-imidazole (M6434) were investigated in experimental models of lethal shock produced by hemorrhage, injection of endotoxin, or coronary ligation. M6434 improved the survival rate of rabbits in hemorrhagic shock. M6434, at the dose of 3 or 10 micrograms/kg/min, completely reversed the decreases in the blood pressure and the urine output of shocked rabbits, but did not affect the decreased regional blood flow through the kidneys in the animals. Survival rates of cardiogenic-shock rats improved, and the content of ATP and creatine phosphate in myocardium of these animals were restored by the treatment with 1 or 3 micrograms/kg/min of M6434. Intravenous infusion of M6434, at a dose of 3 or 10 micrograms/kg/min for 3 hr, increased the survival rate of the endotoxin-shocked rabbits. These results indicate that M6434 may be evaluated as a possible therapeutic agent for shock.     

Influence of hydrogen sulfide on zymogen activation of homocysteineinduced matix metalloproteinase-2 in H9C2 cardiocytes

Objective: To observe the influence of different concentrations of homocysteine(Hcy) and hydrogen sulfide(H2S) on the secretion and activation of matix metalloproteinase-2(MMP-2) in cardiocytes so as to search for new ways to fight against myocardial tissue fibrosis. Methods: Cardiocytes H9C2 was cultured in vitro and different concentrations of Hcy and H2 S were added for 6-h and 24-h cultivation. MTT cell proliferation assay was applied to test the activation change of cardiocytes H9C2 after affecting by different concentrations of Hcy and H2 S. ELISA and MTT were employed to detect the expression and enzymatic activity of MMP-2. Results: The H9C2 cell inhibition of activity was more significant with 1 000 μmol/L of Hcy as compared with other concentrations(P0.001). With 2.5-100.0 μmol/L Hcy and 0.1, 1.0 and 10.0 mmol/L H2 S, the activity of H9C2 did not change significantly(P0.05). Hcy with concentrations of 10, 50 and 100 μmol/L could increase the quantity of MMP-2 secreted by cardiocytes H9C2, and the interaction strength was concentration-dependent(P0.05). After interacting with 100 μmol/L of Hcy for 6 h, the zymogen activation effect of MMP-2 was stronger than that of the 2.5-25 μmol/L group(P0.05). After interacting with Hcy and H2S(1.0 mmol/L) for 6 h and 24 h, the activation effect of MMP-2 was stronger than those interacted with 10, 25, 50 and 100 μmol/L of Hcy(P0.05). Conclusions: Hcy can increase the production of MMP-2 secreted by H9C2 cell and improve its zymogen activation. Besides, the interaction strength is concentration-dependent; while H2 S can up-regulate the activation of MMP-2 and co-promote the activation of MMP-2 with Hcy as well.     

间羟胺对感染性休克患者血压和肾脏功能的影响

目的观察间羟胺对感染性休克患者血压、心率和肾脏功能的影响。方法根据病情相近、病因相同、年龄相仿的原则收集1995年以来在我科ICU接受治疗的感染性休克患者70例。所有患者在休克发生后,均根据病情变化随时调整间羟胺用量,以维持血压稳定。然后根据临床使用间羟胺剂量的大小,将患者分成3组:小剂量组[A组,n=23,最大泵速为0.5～5μg/（kg.min）]、中剂量组[B组,n=23,最大泵速为6～10μg/（kg.min）]、大剂量组[C组,n=24,最大泵速为>11μg/（kg.min）]。在治疗前对患者进行APACHEIII评分,记录其血压、心率变化及尿量、BUN（血尿素氮）、CRE（肌酐）、尿ALB（白蛋白）和β2-MG（β2-微球蛋白）定量等肾功指标变化。结果抗休克治疗前,B组患者的APACHEIII评分显著高于A组,但低于C组（P<0.01）,说明3组患者的病情依次加重;所有患者BUN、CRE、尿ALB和β2-MG定量均异常升高,但组间差异无统计学意义;抗休克治疗开始后,患者尿量、BUN、CRE及尿ALB和β2-MG定量也逐步恢复（与治疗前相比,均P<0.01）,但组间各指标随时间变化差异无统计学意义。结论间羟胺用于感染性休克时,患者肾功的恢复与血流动力学的稳定相关,而与间羟胺剂量的关系不大。     

Regional blood flow and metabolism in canine endotoxin shock before, during, and after infusion of glucose-insulin-potassium (GIK)

Glucose-insulin-potassium infused (GIK) during endotoxin shock causes increased cardiac output (CO) accompanied by decreased systemic vascular resistance. We have studied the effects of GIK on the distribution of cardiac output with radioactive microspheres to see if this decrease in resistance is equally distributed over all organs. GIK resulted in increased CO and increased flow to heart, splanchnic bed, kidneys, adrenals, and skeletal muscle, but fractional flow to these organs did not change. Thirty minutes after the GIK infusion, CO and organ flow had fallen again and differences between the endotoxin and control groups were no longer significant. GIK thus increases CO during endotoxin shock but does not influence its distribution. Systemic oxygen transport increased after GIK, but oxygen extraction decreased. Myocardial and splanchnic oxygen consumption did not change significantly. Oxygen extraction also diminished in these areas after GIK. GIK did not influence serum lactate: In both groups lactate increased significantly.     

Adrenocortical (dys)function in septic shock - a sick euadrenal state

A central feature of the endocrine pathophysiology of septic shock is thought to be the existence of adrenal dysfunction. Based on changes in glucocorticoid secretion and responsiveness, protein binding, and activity. These changes have been described by the terms "Relative Adrenal Insufficiency" (RAI), or "Critical Illness Related Corticosteroid Insufficiency" (CIRCI), and form part of the rationale for trials of glucocorticoid treatment in septic shock. Diagnostic criteria for these conditions have been based on plasma cortisol profiles and have proven notoriously difficult to establish. The uncertainty in this area arises from the inability of current tests to clearly identify who is truly glucocorticoid "deficient" at a cellular level, and hence who requires supplemental glucocorticoid administration. Emerging data suggest that there may be abnormalities in the tissue activity of glucocorticoids in patients with severe sepsis and plasma profiles may not be reliable indicators of tissue glucocorticoid activity, We put forward an alternative point of view, that is the spectrum of adrenocortical dysfunction in sepsis - plasma and tissue, can be grouped under the umbrella of a "sick euadrenal syndrome" rather than an adrenocortical insufficiency.