Yu-Ping Zhang

Mesenteric lymph duct ligation against renal injury in rats after hemorrhagic shock

Background: The kidney is a common target in multiple organ dysfunction syndrome (MODS). The aim of this study is to determine the role of intestinal lymphatic pathway on renal injury in hemorrhagic shock rats. Methods: Wistar rats were divided into sham, shock, and ligation groups. The hemorrhagic shock model was induced in the shock and ligation groups. After resuscitation, the mesenteric lymph ducts were ligated in the ligation group. Blood from the carotid artery was taken to determine renal functional indices. The kidneys were used to observe histomorphological changes at 6 h after resuscitation. In addition, kidney homogenate was used to determine malondialdehyde (MDA), superoxide dismutase (SOD), tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6), and myeloperoxidase (MPO) levels at 90 min after shock and 0, 1, 3, 6, 12, and 24 h after resuscitation. And the survival rate of 24 h was recorded. Results: The survival rate in shock group was obviously lower than sham and ligation groups. The urea and creatinine contents in the serum of shock and ligation groups were significantly higher than the sham group; the indices in the ligation group were significantly lower than the shock group. Histological studies showed various degrees of renal injury in the shock and ligation groups with a lesser severity in the ligation group. MDA, TNFα, IL-6, and MPO in renal homogenate of the shock group were raised, and the activity of SOD was lower in comparison to the sham group. Further, MDA, TNFα, IL-6, and MPO in renal homogenate of the ligation group at 6, 12, and 24 h were lower, and the SOD activity was higher than that of the shock group at the same time points. Conclusion: The mesenteric lymph duct ligation could be used to attenuate renal injury in shock rats. Its mechanism might be related to reducing the polymorph nuclear (PMN) and decreasing inflammatory mediator and free radical.

Exogenous normal lymph alleviates lipopolysaccharide-induced acute kidney injury in rats.

Abstract Background: Acute kidney injury (AKI) is a common pathological process which occurs in hemorrhage, intoxication, etc. It has been shown that the lymphatic circulation plays an important regulatory role in the pathogenesis of hemorrhage shock, and that exogenous normal lymph (ENL) has a beneficial effect on multiple organ injuries. In the present study, we investigated the effect of ENL on lipopolysaccharide (LPS)-induced AKI in rats. Methods: The AKI was induced by the jugular vein injection of LPS (iv, 15 mg/kg). After 15 min of LPS injection, saline or ENL without cell components (5 mL/kg) was iv infused at the speed of 0.5 mL per minute. Then, the renal function indices in plasma and renal histomorphology, and the levels of P-selectin, intercellular adhesion molecule-1 (ICAM-1), myeloperoxidase (MPO) and Na+-K+-ATPase in renal tissue were assessed at 3 or 6 h after LPS injection. Results: LPS induced a severe kidney injury including increased levels of urea, creatinine in plasma, aggrandized activities of ICAM-1 and MPO in renal tissue, and decreased the Na+-K+-ATPase activity in renal cells. These deleterious effects of LPS were significantly ameliorated by ENL treatment. Conclusion: The present results indicate that ENL protect against LPS-induced AKI, suggesting an alternative therapeutic strategy for treatment of kidney injury accompanied with severe infection or sepsis.

Mesenteric lymph return is an important contributor to vascular hyporeactivity and calcium desensitization after hemorrhagic shock.

ABSTRACT Vascular hyporeactivity is an important factor in irreversible shock, whereas calcium desensitization is one of the mechanisms of vascular hyporeactivity, and the intestinal lymphatic pathway plays an important role in multiple organ injury after severe hemorrhagic shock (HS). In this study, our aims were to determine the effects of mesenteric lymph on vascular reactivity during HS and the mechanisms involved. First, the in vivo pressor response was observed by intravenous injection of norepinephrine (3 &mgr;g/kg) at different time points after HS. We found that mesenteric lymph duct ligation (MLDL) and mesenteric lymph drainage (MLD) enhanced the pressor response at multiple time points after shock. Next, vascular reactivity and calcium sensitivity in superior mesenteric artery (SMA) vascular rings were examined using an isolated organ perfusion system. Vascular reactivity and calcium sensitivity were higher for SMA rings from rats that had undergone HS plus MLDL or MLD that those from rats that had undergone only HS. The effects of MLDL and MLD on vascular reactivity and calcium sensitivity were significantly increased following incubation with the calcium sensitizer angiotensin II and were reduced after incubation with the calcium sensitivity inhibitor insulin. When SMA rings from normal rats were incubated with mesenteric lymph from rats subjected to HS, lymph obtained 0 to 0.5 h after shock enhanced vascular reactivity and calcium sensitivity, whereas lymph obtained 1 to 3 h after shock blunted these effects. We finally examined vascular reactivity and calcium sensitivity in HS rats subjected to MLD at 0 to 3 h or 1 to 3 h after shock. We found that contractile activity of SMAs in response to norepinephrine or Ca2+ was higher in HS rats subjected to MLD at 1 to 3 h after shock compared with rats subjected to MLD at 0 to 3 h after shock. These results indicate that mesenteric lymph return plays an important role in biphasic changes in vascular reactivity during HS. Even more importantly, mesenteric lymph 1 h after shock was an important contributor to vascular hyporeactivity, and its mechanism of action was related to calcium desensitization. Targeting lymph may therefore have therapeutic potential in the treatment of severe shock-induced hypotension.

Exogenous Normal Lymph Alleviating Kidney Injury by Improving Coagulation Function in Disseminated Intravascular Coagulation Rats

Aim: To investigate the effect of exogenous normal lymph on kidney injury in disseminated intravascular coagulation (DIC) rats and to probe its mechanism. Methods: The DIC model was established by intravenous injection of Dextran 500. After 6 min, normal lymph without cell components was infused in the lymph group. After 40 min, the renal and coagulation function indices and renal histomorphology were observed. Results: Serum urea and creatinine in the model group were significantly higher than in the control and lymph groups. Renal morphological study showed red blood cell silting and casts forming in the model group. The prothrombin time (PT), prothrombin time ratio (PTR), activated partial thromboplastin time (APTT), and thrombin time of lymph and model groups were higher than those in the control group, whereas fibrinogen was lower. The PT, PTR, and APTT were prolonged in the lymph group than in the model group. The platelet functions of the lymph and model groups were higher than in the control group, but platelet aggregation rate and thrombosis-forming indices were lower than in the control group; the platelet adhesive and aggregation rates and thrombosis dry weight of the lymph group were lower than those of the model group. Conclusion: Exogenous normal lymph could alleviate kidney injury in DIC rats, which may be related to the improving coagulation function.

Role of RhoA in regulating the pump function of isolated lymphatics from hemorrhagic shock rats.

ABSTRACT The aim of this present study was to examine changes in RhoA protein levels and the role in RhoA in lymphatic contractility and reactivity after hemorrhagic shock. Levels of RhoA and phospho-RhoA in lymphatic tissue isolated from hemorrhagic shock rats were measured, and the contractility and reactivity to substance P of lymphatics isolated from control rats and rats subjected to shock 0.5 and 2 h were determined with an isolated lymphatic perfusion system at a transmural pressure of 3 cmH2O. At the same time, lymphatics isolated from rats subjected to shock 0.5 and 2 h were incubated with agonists and antagonists of RhoA/Rho kinase signaling. Contractile frequency, end-diastolic and end-systolic diameter, and passive diameter were recorded and used to calculate lymphatic tonic index, contractile amplitude, and fractional pump flow. After stimulation with a gradient of substance P, the differences between the preadministration and postadministration values of contractile frequency, contractile amplitude, tonic index, and fractional pump flow were calculated to further assess lymphatic reactivity. RhoA protein levels were significantly increased at 0.5 h after shock but decreased at 2 and 3 h after shock; p-Rho levels were initially increased after shock and subsequently decreased. The contractility and reactivity of 0.5-h-shocked lymphatics were significantly reduced by the RhoA antagonist C3 transferase and the Rho kinase antagonist Y-27632. The RhoA agonist U-46619 increased the contractility and reactivity of 2-h-shocked lymphatics, whereas Y-27632 suppressed the effect of U-46619. Okadaic acid, an inhibitor of myosin light-chain phosphatase, had no effect on the contractility of 2-h-shocked lymphatics, but improved lymphatic reactivity. These results suggest that RhoA is involved in the modulation of lymphatic pump function during hemorrhagic shock and that its effects may be mediated by Rho kinase and MLCP.

Lymphatic hyporeactivity and calcium desensitization following hemorrhagic shock.

ABSTRACT The lymphatic circulation is an important component of the circulatory system. In preliminary studies, we found contractile activity of lymphatic vessels to be decreased during severe shock. In the present study, our aim was to observe changes in lymphatic reactivity to norepinephrine (NE) and to explore the mechanism of calcium sensitivity in rats subjected to hemorrhagic shock (HS). Thirty-two Wistar rats were randomly divided into sham and shock groups, and changes in lymphatic pressure and contractility of mesenteric lymphatics in response to NE were measured at different time points after shock. The results showed that NE-induced changes in lymphatic pressure were decreased at 1 h after shock and that hyporeactivity was maintained for 3 h after shock. The reactivity of mesenteric lymphatics to NE in the shock group at 1 to 2 h after shock was significantly lower than that of the sham group and before shock. The other 49 rats were divided into sham, shock 1 h, and shock 2 h groups for isolation thoracic duct rings. Forty-eight isolated lymphatics per group were used to assay lymphatic reactivity to NE and calcium sensitivity in an isolated vessel perfusion system. The NE concentration-response curves for postshock lymphatic rings (1 or 2 h) and calcium concentration-response curves after shock (2 h) were shifted to the right; isolated lymphatic reactivity to NE and contraction in response to calcium were markedly reduced in shock groups. Lymphatic reactivity to NE and calcium sensitivity were significantly increased in the 2-h shock group following incubation with the calcium sensitizer angiotensin II, and the lymphatic reactivity was reduced after incubation with the calcium sensitivity inhibitor insulin. In conclusion, lymphatic reactivity declines progressively during HS as a result of calcium desensitization. The results suggest that lymphatic hyporeactivity is one of the mechanisms of lymphatic hypocontraction in rats subjected to HS.

The mechanism of myocardium and pancreas injury in rabbits with acute renal failure might be related to myeloperoxidase and membrane pump activities

There is increasing evidence indicating that the distant organ injury is a major contributor of high mortality in patients subjected to acute renal failure (ARF). However, sources and mechanisms that ARF causes distant organ injury remain to be determined. The aim of this study is to explore the mechanism from polymorphonuclear neutrophil (PMN) sequestration and membrane pump suppression. To achieve this, we examined myeloperoxidase (MPO), a marker of PMN accumulation in tissues, and membrane pump activities of heart, pancreas, and kidney in two ARF rabbit models. Rabbits are randomly assigned to control, HgCl2-treated, and glycerin-treated groups. ARF animal models are established by hypodermic injection of 1% HgCl2 with 1.3 mL/kg bodyweight (bw) in HgCl2-treated group or intramuscular injection of 50% glycerin with 10 mL/kg bw in glycerin-treated group, respectively, and all animals in each group are further divided into 12 h, 24 h, and 48 h subgroups with each consisting of six rabbits. Six healthy rabbits serve as control group. Results have shown that MPO activities of kidney, myocardium, and pancreas in two model groups were significantly increased than control group at diverse time points. Membrane pump activities of kidney in two model groups are significantly lower than the control group at multiple time points. Moreover, Na+-K+-, Ca2+-, Mg2+-, and Ca2+-Mg2+-ATPase activities of myocardium and pancreas in two model groups are gradually declined with the development of ARF. These findings suggest that PMN sequestration and membrane pump suppression plays an important role in the pathogenesis of ARF and also a major mechanism of myocardium and pancreas injury during the process of ARF.

Postshock mesenteric lymph drainage ameliorates vascular reactivity and calcium sensitivity through RhoA

BACKGROUND Vascular hyporeactivity plays an important role in the pathogenesis of severe shock. Previous studies have shown that postshock mesenteric lymph (PSML) blockage ameliorates the vascular reactivity and calcium sensitivity, and RhoA is involved in the regulation of vascular reactivity after hemorrhagic shock. Therefore, the present study tested whether small GTPase RhoA mediates the improvement of the vascular reactivity and calcium sensitivity in superior mesenteric artery (SMA) of rats with PSML drainage. MATERIALS AND METHODS The hemorrhagic shock model (blood pressure to 40 ± 2 mm Hg) was established, and PSML was drained from immediate hypotension for 3 h, after which SMA was isolated, and the vascular reactivity and calcium sensitivity were tested in the presence of RhoA agonist (U-46619) or inhibitor (C3 transferase). The protein expressions of small GTPase RhoA and phospho-RhoA were also examined in SMA. RESULTS The hemorrhagic shock resulted in a significant decrease in the SMA reactivity and calcium sensitivity, which was enhanced by the application of U-46619 to the SMA. In contrast, the PSML drainage ameliorated the deleterious effect of the hemorrhagic shock on the SMA. This beneficial effect of the PSML drainage was abolished by C3 transferase. Western blotting revealed that the expressions of the RhoA and phospho-RhoA in SMA tissue obtained from the shock group were significantly decreased, and the PSML drainage markedly enhanced these protein expressions. CONCLUSIONS RhoA is an important contributor to the PSML drainage-induced amelioration of the vascular reactivity and calcium sensitivity in rats with hemorrhagic shock.

Exogenous normal lymph alleviates microcirculation disturbances and abnormal hemorheological properties in rats with disseminated intravascular coagulation

Disturbances of the microcirculation and abnormal hemorheological properties are important factors that play an important role in disseminated intravascular coagulation (DIC) and result in organ dysfunction or failure. In the present study, we established an animal model of DIC using intravenous Dextran 500 in rats, and used exogenous normal lymph corresponding to 1/15 of whole blood volume for injection through the left jugular vein. We found that normal lymph could improve the blood pressure and survival time of rats with DIC. The results regarding the mesenteric microcirculation showed that the abnormality of the diameter of mesenteric microvessels and micro-blood flow speed in the DIC+lymph group was significantly less than in the DIC+saline group. Whole blood viscosity, relative viscosity, plasma viscosity, hematocrit (Hct), erythrocyte sedimentation rate (ESR), and electrophoresis time of erythrocytes were significantly increased in the DIC+saline group compared to the control group. The electrophoretic length and migration of erythrocytes from the DIC+saline and DIC+lymph groups were significantly slower than the control group. Blood relative viscosity, Hct, ESR, and electrophoretic time of erythrocytes were significantly increased in the DIC+lymph group compared to the control group. Whole blood viscosity, relative viscosity and reduced viscosity were significantly lower in the DIC+lymph group than in the DIC+saline group, and erythrocyte deformability index was also significantly higher than in the DIC+saline and control groups. These results suggest that exogenous normal lymph could markedly improve the acute microcirculation disturbance and the abnormal hemorheological properties in rats with DIC induced by Dextran 500.

The Mechanism of Spleen Injury in Rabbits with Acute Renal Failure

Immune function disorders are common during acute renal failure (ARF), but the mechanisms are unknown. As the spleen is the largest organ of the immune system, we aimed to observe if there are morphological changes in the spleen in rabbits with ARF. In addition, we tried to explore its mechanism from the perspective of oxygen free radicals, nitric oxide (NO), myeloperoxidase (MPO), and membrane pump activities. ARF animal models were established by either hypodermic injection of 1.3 mL/kg bw 1% HgCl2 or intramuscular injection of 10 mL/kg bw 50% glycerin. Animals were divided into 12 h, 24 h, and 48 h treatment groups with six rabbits in each group. Compared with control animals, congestion was found in the spleen and splenic trabeculae were increased in the two ARF model groups at multiple time points. The malonaldehyde, NO, nitric oxide synthase, and MPO levels in the ARF models were increased compared with the control group at 24 h or 48 h, and the superoxide dismutase and adenosine triphosphatase activities were significantly lower than the levels in the control group at multiple time points. These indices of free radical damage were induced gradually with ARF development, and there were statistically significant differences at different time points. These data suggested that histological damage of spleen during ARF may lead to immune disorders, which might be related to free radical injury, NO excessive release, polymorphonuclear neutrophils (PMN) sequestration, and membrane pump dysfunction.