单唾液酸神经节苷脂对体外循环大鼠炎性反应的影响

目的 评价单唾液酸神经节苷脂(GM1)对体外循环(CPB)大鼠炎性反应的影响.方法 成年雄性SD大鼠24只,体重350 ～ 450 g,4～6月龄,采用随机数字表法,将其分为3组(n=8):假手术组(S组)、CPB组、CPB+ GM1组(G组).G组在预充液中加入GM1 20 mg/kg;C组预充液中加入等容量生理盐水.CPB组和G组于CPB停止后3h时,S组于相应时点,取颈静脉血样,采用ELISA法测定血浆神经元特异性烯醇化酶(NSE)和S-100β蛋白浓度,采用放射免疫分析法测定血浆TNF-α和IL-6浓度;取海马组织,采用Western blot法检测海马基质金属蛋白酶-9(MMP-9)、IL-10表达及NF-κB活性.结果 与S组比较,CPB组和G组血浆NSE、S-100β蛋白、TNF-α和IL-6浓度升高,海马MMP-9表达上调,NF-κB活性增强,IL-10表达下调(P＜0.05);与CPB组比较,G组血浆NSE、S-100β蛋白、TNF-α和IL-6浓度降低,海马MMP-9表达下调,NF-κB活性减弱,IL-10表达上调(P＜0.05).结论 GM1减轻CPB诱发大鼠脑损伤的机制可能与抑制中枢和全身炎性反应有关.     

The effect of methylprednisolone treatment on the cardiopulmonary bypass-induced systemic inflammatory response.

OBJECTIVE: Cardiac surgery with cardiopulmonary bypass (CPB) is associated with an inflammatory response caused by contact of blood with artificial surfaces of the extracorporeal circuit, ischemia-reperfusion injury, and release of endotoxin. The inflammatory reaction involves activation of complement leucocytes, and endothelial cells with secretion of cytokines, proteases, arachidonic acid metabolites, and generation of oxygen derived free radicals (OFR) by polymorphonuclear neutrophils (PMN). Although this inflammatory response to CPB often remains at subclinical levels, it can also lead to major organ dysfunction. A number of studies have demonstrated that treatment of patients with a high-dose (30 mg/kg) of corticosteroids (methylprednisolone) attenuates the CPB-induced SIR and improves the outcome of patients undergoing cardiac surgery. However, large doses of steroids can cause abnormal metabolic responses such as metabolic acidosis and hyperglycemia. In the present study, we examined the efficacy of low doses of methylprednisolone (5 and 10 mg/kg) to attenuate the CPB-induced inflammatory response, during and after heart operations. METHODS: Thirty-six adult patients undergoing cardiac surgery, were randomized into three groups: (1) control group: group A; (2) methylprednisolone, 5 mg/kg body weight: group B; and (3) methylprednisolone, 10 mg/kg body weight: group C. Plasma levels of the cytokines interleukin-6 (IL-6) and TNF-alpha were analyzed by enzyme-linked immunosorbent assay, before, during, and after CPB. OFR production was determined by cytofluorometry (FACS) at the same end points. RESULTS: No significant differences in age, body weight, CPB time, and cross-clamp time were observed among the three groups. CPB induced a marked increased in cytokine release and OFR generation. Low-dose of methylprednisolone (5 mg/kg) effectively reduced the increase in TNF-alpha and IL-6 secretion (P<0.05 compared to control group) after release of the cross-clamp. However, OFR generation was significantly reduced with a greater dose of methylprednisolone (10 mg/kg). CONCLUSIONS: The results indicate that a single low-dose of methylprednisolone (10 mg/kg) reduces the inflammatory reaction during and after CPB, by inhibition of proinflammatory cytokine release and OFR generation after release of the aortic cross-clamp.     

Inducible nitric oxide synthase in renal transplantation

The importance of the endothelial isoform of nitric oxide synthase (eNOS) has been well established. Endothelium-derived nitric oxide has been shown to be essential for vascular homeostasis and modulation of eNOS has thus become a target in prevention of cardiovascular disease. The role of the inducible form of nitric oxide synthase (iNOS) in vascular biology, however, is less clear. Classically, iNOS has been regarded as an enzyme that produces nmolar amounts of the nitric oxide radical, thereby leading to cellular damage. More recent data, however, have shown that the iNOS can be a superoxide, peroxynitrite as well as a nitric oxide-producing enzyme, while the biological effects of iNOS probably depend upon the sort of radical species released by the enzyme as well as the anti-oxidant capacity of the cellular microenvironment of the enzyme. This brief review discusses these aspects in relation to renal transplantation.     

The systemic inflammatory response to cardiopulmonary bypass

Although our understanding of the basic pathophysiology of systemic inflammatory response to CPB has significantly advanced in the last 2 decades, these experimentally derived ideas have yet to be fully integrated into clinical practice. Treatment of the systemic inflammatory response to CPB is also confounded by the fact that inhibition of inflammation might disrupt protective physiologic responses or result in immunosuppression. Although it is unlikely that no single therapeutic strategy will ever be sufficient in of itself to totally prevent CPB-associated morbidity, the combination of multiple pharmacologic and mechanical therapeutic strategies, each selectively targeted at different components of the inflammatory response, may eventually result in significantly improved clinical outcomes following cardiac surgery.     

体外循环心脏手术围术期肺的炎性反应

目的 研究体外循环心脏手术过程中肺的炎性反应和观察术后肺功能受损的程度。方法 择期心脏瓣膜置换患者20例,在CPB前,主动脉开放心脏复跳1、3、5、10 min分别采右心房与肺静脉血检测PMN、CD11b、IL-8、IL-10、MDA和SOD水平以及对术后肺功能进行观察。结果 血中上述物质的水平,肺静脉明显高于右心房,主动脉开放心脏复跳后各时点较CPB前显著性升高(P<0.05)。与CPB前比较,术后各时点所有患者肺泡OI、VD/VT及P(A-a)O2分别较CPB前增大(P<0.05),CaO2、SaO2和PaO2均呈下降趋势(P<0.05)。结论 体外循环过程中肺发生了炎性反应并造成肺损害,肺损伤后肺功能的改变为亚临床性。     

一氧化氮对肺泡巨噬细胞致炎效应的调节作用

目的 探讨一氧化氮（ＮＯ）对肺泡巨噬细胞致炎效应的调节作用。方法 内毒素（ＬＰＳ）刺激体外培养的小鼠肺泡巨噬细胞,ＴＮＦα等细胞因子释放及ＮＯ对细胞因子释放的影响。结果ＬＰＳ诱导巨噬细胞释放炎症性细胞因子的时效关系不同,肺泡巨噬细胞释放ＴＢＦα、ＩＬ－１α、ＩＬ－６的峰值时间分别为６、８、２４小时。ＮＯ合成酶抑制剂甲基异硫脲明显降低ＬＰＳ诱导的ＮＯ释放,同时强烈刺激肺泡巨噬细胞释放ＩＬ－１β、ＩＬ     

米力农对心肺转流促炎细胞因子反应及心肌损伤的影响

目的探讨米力农对心肺转流(CPB)诱发的促炎细胞因子反应及心肌损伤的影响。方法24例择期瓣膜替换术病人,随机分成米力农组(M组)和对照组(C组),每组12例。麻醉诱导开始前,M组给予米力农30μg/kg负荷量静注,继以0.5μg·kg-1·min-1持续静脉输注;C组以相同速度输注等量生理盐水。分别于术前(T1)、CPB60min(T2)、CPB结束后2h(T3)、4h(T4)及24h(T5)各时间点测定动脉血中下列各项指标:肿瘤坏死因子α(TNFα)、白细胞介素6(IL6)、白细胞介素8(IL8)、血浆过氧化脂质(LPO)、心肌肌酸激酶同工酶(CKMB)。结果与T1比较,其余各时点两组TNFα、IL6、IL8、LPO、CKMB均明显升高(P<0.05或P<0.01),但M组升高明显低于C组(P<0.05)。结论米力农能有效抑制CPB诱发的促炎细胞因子反应和心肌损伤。     

小剂量氯胺酮对体外循环促炎细胞因子反应及心肌损伤的影响

目的 探讨小剂量氯胺酮对体外循环（CPB）诱发的促炎细胞因子反应及心肌损伤的影响。方法 20例择期瓣膜替换术病人,随机分成氯胺酮组（n＝10）和对照组（n＝10）。氯胺酮组于麻醉诱导和转流开始时按1mg.kg^-1静注氯胺酮,对照组则采用等量生理盐水注射。分别于术前（T1）、CPB60min（T2）、CPB结束后2h（T3)、4h(T4)及24h（T5）各时间点测定动脉血中下列各项指标;肿瘤坏死因子－α（TNF－α）、白细胞介素－6（IL－6）、白细胞介素－8（IL－8）、血浆过氧化脂质（LPO）、心肌肌酸酶同工酶（CK－MB）。结果 与术前（T1）比较,两组TNF－α、IL－6、IL－8、LPO、CK－MB均明显升高（P＜0．05或0．01）;但氯胺酮组T2－T5TNF－α、IL－6、IL－8浓度、T3LPO浓度和T3、T4、CK－MB活性均显著低于对照组（P＜0．05）。结论 小剂量氯胺酮能有效抑制CPB诱发的促炎细胞因子反应和心肌损伤。     

Vascular smooth muscle contraction is an independent regulator of endothelial nitric oxide production

This investigation was conducted to determine whether endothelial nitric oxide (NO) production is regulated by vascular smooth muscle contraction. Unperfused ring segments of rat aorta and mesenteric artery were studied using isometric tension recording (n = 6-8 in all experiments). Following a reference contraction to K+ 80 mM (100%), arteries were left either unstimulated or stimulated by different concentrations of K+ or prostaglandin F2alpha (PGF2alpha) to induce different levels of vascular precontraction. N(G)-nitro-L-arginine methyl ester (L-NAME 0.1-300 microM) or NS 2028 (0.03-3 microM), which is a new specific inhibitor of the NO-sensitive guanylate cyclase, was then added at increasing concentrations to evaluate endothelial NO production. L-NAME and NS 2028 produced a concentration-dependent vasoconstrictor response which was progressively enhanced with increasing levels of precontraction. For L-NAME, this amounted in aorta to (% of reference contraction): 35+/-1% and 105 +/- 4% (precontraction by K(+) 20 and 30 mM) and 22+/-1%, 89+/-1%, 138+/-1% and 146+/-2% (precontraction by PGF2alpha 0.5, 1, 2 and 3 microM). A similar coupling was found in the mesenteric artery. A precontraction as little as 2% was enough to trigger a vasoconstrictor response to L-NAME. In contrast, L-NAME and NS 2028 had no effect in non-contracted arteries, not even when passive mechanical stretch was increased by 100%. The results suggest (i) that endothelial NO formation is progressively increased with increasing vascular tone, and (ii) that vascular isometric contraction per se stimulates endothelial NO formation. It is concluded, that active vascular smooth muscle contraction is an independent regulator of endothelial NO production.     

Inducible nitric oxide synthetase is expressed in adult but not fetal pig pancreatic islets

Abstract: Cytokine-induced expression of inducible nitric oxide synthetase (iNOS) and production of nitric oxide (NO) by pancreatic islet cells has been suggested as one potential mechanism for beta cell destruction. In this study, we investigated the role of iNOS and NO in islet primary non-function. Islets were assessed for their function, viability and expression of iNOS. Adult rat and pig islets isolated by collagenase digestion and fetal pig pancreas (FPP) grafts isolated by collagenase digestion or high oxygen culture were transplanted into C57BL6 mice and nude mice. iNOS protein was detected by immunohistochemistry. iNOS protein was found in normal rat and pig pancreas and adult rat and pig islets that were isolated by collagenase digestion and transplanted into either C57BL6 mice or nude mice. iNOS was not detected in fetal pig islet grafts, regardless of whether collagenase was used in the isolation process. In adult pig islet grafts, the presence of iNOS protein correlated with high levels of islet cell apoptosis and primary non-function. Despite the persistent presence of iNOS in rat islets, there was no evidence that it had a deleterious effect on rat islet viability, or function. Therefore, in isolated adult pig islets, there was a correlation between iNOS expression and apoptosis, suggesting that iNOS activation may be deleterious to the adult pig islets. However, other factors such as the fragility of the islet capsule may be equally important. By contrast, fetal pig islets did not express iNOS and this may be an important reason for their enhanced viability when compared with adult islet tissue.     

Cerebral response to haemodilution during cardiopulmonary bypass in dogs: the role of nitric oxide synthase

During cardiopulmonary bypass, haemodilution is standard practice and is accompanied by increases in cerebral blood flow (CBF). We investigated if changes in cerebral vascular resistance (CVR) during cardiopulmonary bypass-haemodilution are dependent on nitric oxide synthase. The cerebral response to haemodilution in nine dogs treated with the nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME), was compared with a control group (n = 8). Both groups underwent serial isovolaemic haemodilution (target packed cell volumes 0.39, 0.26, 0.19 and 0.14) using 6% dextran 70. CBF, CVR and cerebral metabolic rate for oxygen (CMRO2) were measured. While initial CVR was different in the two groups, haemodilution-dependent reductions in CVR were equivalent and the curves describing the packed cell volume- CVR relationship were parallel in control and nitric oxide synthase inhibition groups. Our data indicate that nitric oxide synthase does not play a primary role in the cerebral response to haemodilution.      

Inducible nitric oxide synthase attenuates endothelium-dependent renal microvascular vasodilation

Previous studies have demonstrated that inducible nitric oxide synthase (iNOS) plays a key pathophysiologic role during sepsis. The present study was designed to delineate the consequences of iNOS activation on renal microvascular function. Male Sprague-Dawley rats were given intraperitoneal injections of lipopolysaccharide (LPS; 4 mg/kg) at 16 h and 4 h before experimentation. Afferent and efferent arteriolar diameters from LPS-treated and control rats were assessed in vitro with the use of the blood perfused juxtamedullary nephron technique. Basal afferent and efferent arteriolar diameters of LPS-treated rats averaged 19.7 +/- 0.9 (n = 7) and 18.3 +/- 1.0 microm (n = 5), respectively, and were similar to those of control rats (20.8 +/- 0.3 [n = 6] and 18.4 +/- 0.6 microm [n = 6], respectively). Superfusion with the selective iNOS inhibitor S,S'-(1,3-phenylenebis[1,2-ethanediyl]) bisisothiourea (PBIT), at the doses of 0.01, 0.1, and 1 microM, significantly decreased afferent and efferent arteriolar diameters in a dose-dependent manner, whereas afferent or efferent arteriolar diameters of control rats were not altered in response to the same doses of PBIT. In the second series of experiments, superfusion with 10 microM acetylcholine (ACh) significantly increased afferent and efferent arteriolar diameters of LPS-treated rats by 14.9 +/- 1.6% (n = 9) and 6.6 +/- 1.1% (n = 6), respectively. The ACh-induced afferent and efferent arteriolar dilator responses were inhibited by superfusion with the nonselective NOS inhibitor N:(omega)-nitro-L-arginine (100 microM). However, afferent and efferent arteriolar dilator responses to ACh were significantly enhanced during selective iNOS inhibition with 1 microM PBIT (40.1 +/- 0.7% and 25.2 +/- 1.3%, respectively). These results suggest that activation of iNOS by LPS increases the influence of nitric oxide on afferent and efferent arteriolar tone and impairs endothelium-dependent nitric oxide effects.