CHANGES OF RHO KINASE ACTIVITY AFTER HEMORRHAGIC SHOCK AND ITS ROLE IN SHOCK-INDUCED BIPHASIC RESPONSE OF VASCULAR REACTIVITY AND CALCIUM SENSITIVITY

Articles on hemorrhagic shock published between 2000 and 2021: A CiteSpace-Based bibliometric analysis

Objective

To conduct a bibliometric analysis of literature on hemorrhagic shock published between 2000 and 2021 with the help of Citespace to explore the current status, hotspots and research trends in this regard, with the results presented in a visualized manner.

Methods

The data over the past 22 years were retrieved from the Web of Science (WOS) Core Collection database and downloaded as the "Full Record and Cited References". Cooperative analysis, cluster analysis, co-citation analysis, and burst analysis were performed based on the data on countries/regions, institutions, journals, authors, and keywords through Citespace.

Results

A total of 2027 articles were retrieved. The number of annual publications fluctuated but was generally on an upward trend. The United States stands out as the most productive country (989 articles), the University of Pittsburgh the most productive publishing institution (109 articles), SHOCK the most cited journal (1486 articles), TAO LI the most productive author (40 articles), DEITCH EA the most cited author (261 times of citation), hemorrhagic shock the most frequent keyword (725 times of occurrence), and "traumatic brain injury" the most covered article in keyword clustering (29 articles). The burst analysis revealed Harvard University as the institution with the highest strength value and the Journal of Trauma and Acute Care Surgery the most important journal. It was also concluded that HASAN B ALAM, AARON M WILLIAMS, and LIMIN ZHANG may continue to publish high-quality articles in the future. In the meanwhile, both "protect" and "transfusion" were considered the hotspots and trends in current research.

Conclusions

The United States has been a major contributor to the publication of the articles over the past 22 years, with the most productive publishing institution, the most cited journal, and the most cited author all coming from the US. Hemorrhagic shock, injury, resuscitation, trauma, models, activation, expression, fluid resuscitation, rats, and nitric oxide are hot topics in relevant research. According to the keyword burst analysis, the areas related to "protect" and "transfusion" may rise as the research directions in the future. However, since the hotspots in the research of hemorrhagic shock are short-lived and fast-changing, the researchers should pay more attention to the development trend in this field.

Role of Tumor Necrosis Factor-α in vascular hyporeactivity following endotoxic shock and its mechanism

BACKGROUND

Vascular hyporeactivity plays an important role in organ dysfunction induced by endotoxic shock. Given that cytokine, such as TNF-α, plays an important role in endotoxic shock, the aim of the present study is to investigate the role of Tumor Necrosis Factor (TNF)-α in vascular hyporeactivity following endotoxic shock and the mechanisms.

METHODS

Lipopolysaccharide (LPS) (1 mg/kg) injection was used for replicating the endotoxic shock model in the rabbit. The changes in the level of TNF-α in plasma in the rabbits model and the contractile response of superior mesenteric arteries (SMA) to norepinephrine (NE) and Ca were observed. The mechanisms in TNF-α-induced vascular hyporeactivity were further explored.

RESULTS

The levels of TNF-α in plasma were gradually increased after 1 hour of LPS administration and reached the peak at 6 hours. The contractile responses of SMA to NE were decreased at 1 hour of LPS and lowest at 6 hour. TNF-α (200 ng/mL) incubation decreased contractile response of SMA to NE significantly. Further studies found that calcium desensitization participated in the occurrence of TNF-α-induced vascular hyporeactivity, the changes were consistent with the changes of vascular reactivity, calcium sensitivities were decreased significantly at 1 hour, 2 hours, 4 hours, and 6 hours after LPS injection. TNF-α (200 ng/mL) incubation could significantly reduce the contractile response of SMA to Ca. The activity of Rho-kinase and the changes of myosin light chain 20 (MLC20) phosphorylation level were significantly decreased at 6 hours following LPS administration, and TNF-α (200 ng/mL) incubation led to a decrease of Rho-kinase and MLC20 phosphorylation. Arginine vasopressin significantly antagonized TNF-α (200 ng/mL)-induced the decrease of the vascular reactivity and calcium sensitivity.

CONCLUSION

TNF-α is involved in vascular hyporeactivity after endotoxic shock. Calcium desensitization plays an important role in TNF-α-induced vascular hyporeactivity after endotoxic shock. Rho-kinase/MLC20 phosphorylation pathway takes part in the regulation of calcium desensitization and vascular hyporeactivity induced by TNF-α. Arginine vasopressin is beneficial to endotoxic shock in TNF-α-induced vascular hyporeactivity.

Selenium Deficiency Affects Uterine Smooth Muscle Contraction Through Regulation of the RhoA/ROCK Signalling Pathway in Mice

Selenium (Se) is considered one of the essential micronutrients for humans and animals, and its effects on physiological functions are multifaceted. In the present study, we investigated the effects of Se deficiency on uterine smooth muscle contraction in mice by studying G protein Rho (RhoA)/Rho kinase (ROCK) signalling pathway-related molecules. The α-sma in smooth muscle tissue of mice was determined. The extracorporeal contraction curve for uterine smooth muscle in mice was determined. Both of these results indicate that Se deficiency impairs the contractile ability of uterine smooth muscle in mice. The expression of mRNA was measured by real-time quantitative PCR. The results showed that there was no significant change in mRNA expression of RhoA, ROCK, myosin light chain phosphatase (MLCP), or myosin light chain (MLC) in tissues. The protein levels were detected by Western blot. The results showed that there were no significant differences in RhoA, ROCK, MLCP, or MLC expression. However, compared with the CG, the concentration of phosphorylated MLC (P-MLC) increased in the SG and the concentration of P-MLC decreased in the DG. The activity of ROCK and MLCP was tested by liquid scintillation. The results suggest that the lack of Se may affect the regulation of MLCP by ROCK. Cellular experiments were performed to compare with results from tissues. There was no significant difference between the two models. The results indicated that Se deficiency affects uterine smooth muscle contraction by regulating the RhoA/ROCK signalling pathway. As the concentration of Se decreases, the activity of MLCP increases, which promotes the dephosphorylation of P-MLC, causing a decrease in contraction.

Dengue Virus Infection of Primary Human Smooth Muscle Cells

Dengue virus (DENV) infection of humans is presently the most important arthropod-borne viral global threat, for which no suitable or reliable animal model exists. Reports addressing the effect of DENV on vascular components other than endothelial cells are lacking. Dengue virus infection of vascular smooth muscle cells, which play a physiological compensatory response to hypotension in arteries and arterioles, has not been characterized, thus precluding our understanding of the role of these vascular components in dengue pathogenesis. Therefore, we studied the permissiveness of primary human umbilical artery smooth muscle cells (HUASMC) to DENV 1-4 infection and compared with the infection in the previously reported primary human umbilical vein endothelial cells (HUVEC) and the classically used, non-transformed, and highly permissive Lilly Laboratories Cell-Monkey Kidney 2 cells. Our results show that HUASMC are susceptible and productive to infection with the four DENV serotypes, although to a lesser extent when compared with the other cell lines. This is the first report of DENV permissiveness in human smooth muscle cells, which might represent an unexplored pathophysiological contributor to the vascular collapse observed in severe human dengue infection.

Role of connexin 43 in vascular hyperpermeability and relationship to Rock1-MLC20 pathway in septic rats

Connexin (Cx)43 has been shown to participate in several cardiovascular diseases. Increased vascular permeability is a common and severe complication in sepsis or septic shock. Whether or not Cx43 takes part in the regulation of vascular permeability in severe sepsis is not known, and the underlying mechanism has not been described. With cecal ligation and puncture-induced sepsis in rats and lipopolysaccharide (LPS)-treated vascular endothelial cells (VECs) from pulmonary veins, the role of Cx43 in increased vascular permeability and its relationship to the RhoA/Rock1 pathway were studied. It was shown that vascular permeability in the lungs, kidneys, and mesentery in sepsis rats and LPS-stimulated monolayer pulmonary vein VECs was significantly increased and positively correlated with the increased expression of Cx43 and Rock1 in these organs and cultured pulmonary vein VECs. The connexin inhibitor carbenoxolone (10 mg/kg iv) and the Rock1 inhibitor Y-27632 (2 mg/kg iv) alleviated the vascular leakage of lung, mesentery, and kidney in sepsis rats. Overexpressed Cx43 increased the phosphorylation of 20-kDa myosin light chain (MLC20) and the expression of Rock1 and increased the vascular permeability and decreased the transendothelial electrical resistance of pulmonary vein VECs. Cx43 RNA interference decreased the phosphorylation of MLC20 and the expression of Rock1 and decreased LPS-stimulated hyperpermeability of cultured pulmonary vein VECs. The Rock1 inhibitor Y-27632 alleviated LPS- and overexpressed Cx43-induced hyperpermeability of monolayer pulmonary vein VECs. This report shows that Cx43 participates in the regulation of vascular permeability in sepsis and that the mechanism is related to the Rock1-MLC20 phosphorylation pathway.

Protein markers related to vascular responsiveness after hemorrhagic shock in rats

BACKGROUND

Vascular hyporesponsiveness is an important pathophysiological feature of some critical conditions such as hemorrhagic shock. Many proteins and molecules are involved in the regulation of the pathologic process, however the mechanism has still remained unclear. Our study was intended to look for the related protein markers involved in the regulation of vascular reactivity after hemorrhagic shock.

METHODS

Differential in-gel electrophoresis and tandem mass spectrometry were applied to quantify the differences of protein expression in the superior mesenteric arteries from hemorrhagic shock and normal rats.

RESULTS

A total of 2317 differentially expressed protein spots in the superior mesenteric arteries of rats before and after hemorrhagic shock were found, and 146 protein spots were selected for tandem mass spectrometry identification. Thirty-seven differentially expressed proteins were obtained, including 3 uncharacterized proteins and 34 known proteins. Among them, heat shock protein beta-1 and calmodulin were the known proteins involved in the occurrence of vascular hyporesponsiveness. Bioinformatics analysis results showed that 18 proteins were related to vasoconstriction, 11 proteins may be involved in other vascular functions such as regulation of angiogenesis and endothelial cell proliferation.

CONCLUSIONS

The changes of vascular responsiveness after hemorrhagic shock in rats may be associated with the upregulation or downregulation of previously mentioned protein expressions. These findings may provide the basis for understanding and further study of the mechanism and treatment targets of vascular hyporeactivity after shock.

Beneficial effects of platelet-derived growth factor on hemorrhagic shock in rats and the underlying mechanisms

Studies have shown that local application of platelet-derived growth factor (PDGF) can be used for the treatment of acute and chronic wounds. We investigated if systemic application of PDGF has a protective effect on acute hemorrhagic shock in rats in the present study. Using hemorrhagic shock rats and isolated superior mesenteric arteries, the effects of PDGF-BB on hemodynamics, animal survival, and vascular reactivity as well as the roles of the gap junction proteins connexin (Cx)40 and Cx43, PKC, and Rho kinase were observed. PDGF-BB (1–15 μg/kg iv) significantly improved the hemodynamics and blood perfusion to vital organs (liver and kidney) as well as vascular reactivity and improved the animal survival in hemorrhagic shock rats. PDGF recovering shock-induced vascular hyporeactivity depended on the integrity of the endothelium and myoendothelial gap junction. Cx43 antisense oligodeoxynucleotide abolished these improving effects of PDGF, whereas Cx40 oligodeoxynucleotide did not. Further study indicated that PDGF increased the activity of Rho kinase and PKC as well as vascular Ca2+ sensitivity, whereas it did not interfere with the intracellular Ca2+ concentration in hypoxia-treated vascular smooth muscle cells. In conclusion, systemic application of PDGF-BB may exert beneficial effects on hemorrhagic shock, which are closely related to the improvement of vascular reactivity and hemodynamics. The improvement of PDGF-BB in vascular reactivity is vascular endothelium and myoendothelial gap junction dependent. Cx43, Rho kinase, and PKC play very important role in this process. These findings suggest that PDGF may be a potential measure to treat acute clinical critical diseases such as severe trauma, shock, and sepsis.

Ryanodine receptor 2 contributes to hemorrhagic shock-induced bi-phasic vascular reactivity in rats

AIM

Ryanodine receptor 2 (RyR2) is a critical component of intracellular Ca(2+) signaling in vascular smooth muscle cells (VSMCs). The aim of this study was to investigate the role of RyR2 in abnormal vascular reactivity after hemorrhagic shock in rats.

METHODS

SD rats were hemorrhaged and maintained mean arterial pressure (MAP) at 40 mmHg for 30 min or 2 h, and then superior mesenteric arteries (SMA) rings were prepared to measure the vascular reactivity. In other experiments, SMA rings of normal rats and rat VSMCs were exposed to a hypoxic medium for 10 min or 3 h. SMA rings of normal rats and VSMCs were transfected with siRNA against RyR2. Intracellular Ca(2+) release in VSMCs was assessed using Fura-2/AM.

RESULTS

The vascular reactivity of the SMA rings from hemorrhagic rats was significantly increased in the early stage (30 min), but decreased in the late stage (2 h) of hemorrhagic shock. Similar results were observed in the SMA rings exposed to hypoxia for 10 min or 3 h. The enhanced vascular reactivity of the SMA rings exposed to hypoxia for 10 min was partly attenuated by transfection with RyR2 siRNA, whereas the blunted vascular reactivity of the SMA rings exposed to hypoxia for 3 h was partly restored by transfection with RyR2 siRNA. Treatment with the RyR agonist caffeine (1 mmol/L) significantly increased Ca(2+) release in VSMCs exposed to hypoxia for 10 min or 3 h, which was partially antagonized by transfection with RyR2 siRNA.

CONCLUSION

RyR2-mediated Ca(2+) release contributes to the development of bi-phasic vascular reactivity induced by hemorrhagic shock or hypoxia.

Bradykinin induces vascular contraction after hemorrhagic shock in rats

BACKGROUND

Bradykinin (BK) has many biological effects in inflammation, allergy, and septic shock. Studies have shown that low doses of BK can induce vascular relaxation and high doses can induce vascular contraction in many pathophysiological conditions, but the role and mechanisms that high doses of BK have on vascular contraction in hemorrhagic shock are not clear.

METHODS

With hemorrhagic-shock rats and hypoxia-treated superior mesenteric artery (SMA), we investigated the role and mechanisms of high doses of BK-induced vascular contraction in hemorrhagic shock.

RESULTS

High doses of BK (500-50,000 ng/kg in vivo or 10(-10) to 10(-5) mol/L in vitro) dose dependently induced vascular contraction of SMA and increased the vascular calcium sensitivity in normal and hemorrhagic-shock rats. Less than 10(-10) mol/L of BK induced vascular dilation BK-induced increase of vascular contractile response and calcium sensitivity was reduced by denudation of the endothelium, 18α-glycyrrhetic acid (an inhibitor of myoendothelial gap junction) and connexin 43 antisense oligodeoxynucleotide. Further studies found that high concentrations of BK-induced vascular contraction in hemorrhagic shock was closely related to the activation of Rho A-Rho kinase pathway and Protein Kinase C (PKC) α and ε.

CONCLUSIONS

High doses of BK can induce vascular contraction in hemorrhagic shock condition, which is endothelium and myoendothelial gap junction dependent. Cx43-mediated activation of Rho A-Rho kinase and Protein Kinase C (PKC) pathway plays a very important role in this process. This finding provided a new angle of view to the biological role of BK in other pathophysiological conditions such as hemorrhagic shock or hypoxia.

Rho kinase acts as a downstream molecule to participate in protein kinase Cε regulation of vascular reactivity after hemorrhagic shock in rats

Our previous study demonstrated that Rho kinase and protein kinase C (PKC) played important parts in the regulation of vascular reactivity after shock. Using superior mesenteric arteries (SMAs) from hemorrhagic shock rats and hypoxia-treated vascular smooth muscle cells (VSMCs), relationship of PKCε regulation of vascular reactivity to Rho kinase, as well as the signal transduction after shock, was investigated. The results showed that inhibition of Rho kinase with the Rho kinase-specific inhibitor Y-27632 antagonized the PKCε-specific agonist carbachol and highly expressed PKCε-induced increase of vascular reactivity in SMAs and VSMCs, whereas inhibition of PKCε with its specific inhibitory peptide did not antagonize the Rho kinase agonist (U-46619)-induced increase of vascular reactivity in SMAs and VSMCs. Activation of PKCε or highly expressed PKCε upregulated the activity of Rho kinase and the phosphorylation of PKC-dependent phosphatase inhibitor 17 (CPI-17), zipper interacting protein kinase (ZIPK), and integrin-linked kinase (ILK), whereas activation of Rho kinase increased only CPI-17 phosphorylation. The specific neutralization antibodies of ZIPK and ILK antagonized PKCε-induced increases in the activity of Rho kinase, but CPI-17 neutralization antibody did not antagonize this effect. These results suggested that Rho kinase takes part in the regulation of PKCε on vascular reactivity after shock. Rho kinase is downstream of PKCε. Protein kinase Cε activates Rho kinase via ZIPK and ILK; CPI-17 is downstream of Rho kinase.

Age and sex differences in vascular responsiveness in healthy and trauma patients: contribution of estrogen receptor-mediated Rho kinase and PKC pathways

Several medical conditions exhibit age- and sex-based differences. Whether or not traumatic shock exhibits such differences with regard to vascular responsiveness is not clear. In a cohort of 177 healthy subjects and 842 trauma patients (21–82 years) as well as different ages (4, 8, 10, 14, 18, and 24 wk; 1 and 1.5 years) and sexes of Sprague-Dawley normal and traumatic shock rats, the age- and sex-based differences of vascular responsiveness and the underlying mechanisms were investigated. Middle-aged and young women as well as female rats of reproductive age had higher vascular responsiveness in the normal condition and a lower decrease in vascular responsiveness after traumatic shock than older men and male rats of identical age. Exogenous supplementation of 17β-estrdiol increased vascular reactivity in both male and femal rats of 8–24 wk and preserved vascular responsiveness in rats following traumatic shock. No effect was observed in rats 1 to 1.5 years. These protective effects of estrogen were closely related to G protein-coupled receptor (GPR)30, estrogen receptor-mediated Rho kinase, and PKC pathway activation. Vascular responsiveness exhibits age- and sex-based differences in healthy subjects and trauma patients. Estrogen and its receptor (GPR30) mediated activation of Rho kinase and PKC using genomic and nongenomic mechanisms to elicit protective effects in vascular responsiveness. This finding is important for the personalized treatment for several age- and sex-related diseases involving estrogen.

Bkca opener, NS1619 pretreatment protects against shock-induced vascular hyporeactivity through PDZ-Rho GEF-RhoA-Rho kinase pathway in rats

BACKGROUND

Our previous study showed that the ischemic preconditioning and pretreatment of adenosine triphosphate-sensitive potassium channel (KATP) opener, pinacidil, may induce a good protective effect on shock-induced vascular hyporeactivity. Whether the pretreatment of opener/activator of the large-conductance calcium-activated potassium channel (Bkca), NS1619, can also induce a protective effect on vascular reactivity and play a beneficial effect on subsequent hemorrhagic shock is not clear.

METHODS

With Sprague-Dawley rats subjected to hemorrhagic shock and their isolated superior mesenteric artery, the protective effect of NS1619 (0.5, 1, 2, and 4 mg/kg) pretreatment (30 minutes before hemorrhage shock) on vascular reactivity and the underlying mechanisms were observed.

RESULTS

NS1619 pretreatment significantly improved the 72-hour survival of hemorrhagic shock rats, alleviated shock-induced decrease of vascular reactivity and calcium sensitivity, and increased the cardiac output and oxygen delivery. NS1619 2 mg/kg had the best effect. These protective effects of NS1619 pretreatment on vascular reactivity and calcium sensitivity were antagonized by RhoA inhibitor, C3 transferase, and Rho kinase antagonist, Y-27632. NS1619 pretreatment up-regulated the activities of RhoA, Rho-kinase, and PDZ-Rho GEF (guanine nucleotide exchange factor). These effects of NS1619 pretreatment were eliminated by RhoA inhibitor, C3 transferase.

CONCLUSION

Bkca opener, NS1619 pretreatment has good protective effect on vascular reactivity and calcium sensitivity, which plays a good beneficial effect on hemorrhagic shock. The mechanism may be mainly through PDZ-Rho GEF-RhoA-Rho kinase pathway. Bkca channel may be a potential target for the treatment of shock-induced vascular hyporeactivity.

Effects of interleukin-1β on vascular reactivity after lipopolysaccharide-induced endotoxic shock in rabbits and its relationship with PKC and Rho kinase

Calcium desensitization plays a critical role in the occurrence of vascular hyporeactivity after shock. Interleukin (IL)-1β participates in the regulation of vascular reactivity via both nitric oxide (NO)-dependent and NO-independent mechanisms. However, the specific NO-independent pathway remains to be established. The issue of whether IL-1β modulates vascular reactivity via regulation of calcium sensitivity in the NO-independent mechanism is unclear. In the current study, effects of IL-1β on vascular calcium sensitivity and its relationship with PKC and Rho kinase were investigated in vivo and in vitro using a rabbit model of lipopolysaccharide (LPS)-induced endotoxic shock and superior mesenteric arteries (SMAs), respectively. The calcium sensitivity profile of SMAs displayed a biphasic change after LPS-induced endotoxic shock (significant increase at 0.5 hour and 1 hour after LPS administration and marked decrease after 2 hours) and was negatively related to changes in serum IL-1β. The IL-1 receptor antagonist, IL-1ra (4 μg/mL), partly reversed LPS-induced calcium desensitization. In vitro incubation with IL-1β (50-200 ng/mL) reduced the calcium sensitivity of SMAs and suppressed the activities of Rho kinase and PKC and the phosphorylation of 20-kDa myosin light chain. These effects of IL-1β were shown to be regulated by the PKC agonist, phorbol 12-myristate 13-acetate, and Rho kinase agonist and antagonist, angiotensin II, and Y-27632, respectively. Our results collectively suggest that IL-1β participates in vascular hyporeactivity after endotoxic shock via regulation of vascular calcium sensitivity. Moreover, this regulatory effect of IL-1β seems closely related to downregulation of the activities of PKC and Rho kinase.

Myosin light chain kinase is necessary for post-shock mesenteric lymph drainage enhancement of vascular reactivity and calcium sensitivity in hemorrhagic-shocked rats

Vascular hyporeactivity is an important factor in irreversible shock, and post-shock mesenteric lymph (PSML) blockade improves vascular reactivity after hemorrhagic shock. This study explored the possible involvement of myosin light chain kinase (MLCK) in PSML-mediated vascular hyporeactivity and calcium desensitization. Rats were divided into sham (n=12), shock (n=18), and shock+drainage (n=18) groups. A hemorrhagic shock model (40±2 mmHg, 3 h) was established in the shock and shock+drainage groups. PSML drainage was performed from 1 to 3 h from start of hypotension in shock+drainage rats. Levels of phospho-MLCK (p-MLCK) were determined in superior mesenteric artery (SMA) tissue, and the vascular reactivity to norepinephrine (NE) and sensitivity to Ca²⁺ were observed in SMA rings in an isolated organ perfusion system. p-MLCK was significantly decreased in the shock group compared with the sham group, but increased in the shock+drainage group compared with the shock group. Substance P (1 nM), an agonist of MLCK, significantly elevated the decreased contractile response of SMA rings to both NE and Ca²⁺ at various concentrations. Maximum contractility (E_max) in the shock group increased with NE (from 0.179±0.038 to 0.440±0.177 g/mg, P<0.05) and Ca²⁺ (from 0.515±0.043 to 0.646±0.096 g/mg, P<0.05). ML-7 (0.1 nM), an inhibitor of MLCK, reduced the increased vascular response to NE and Ca²⁺ at various concentrations in the shock+drainage group (from 0.744±0.187 to 0.570±0.143 g/mg in E_max for NE and from 0.729±0.037 to 0.645±0.056 g/mg in E_max for Ca²⁺, P<0.05). We conclude that MLCK is an important contributor to PSML drainage, enhancing vascular reactivity and calcium sensitivity in rats with hemorrhagic shock.

Mitogen-activated protein kinases regulate vascular reactivity after hemorrhagic shock through myosin light chain phosphorylation pathway

BACKGROUND

Vascular hyporeactivity played an important role in many critical illness including shock or sepsis, but the mechanisms are incompletely understood. The objective of the present study was to investigate the roles of major mitogen-activated protein kinases (MAPKs extracellular signal-regulated kinase [ERK], p38 MAPK, and jun NH2-terminal kinase [JNK]) on vascular reactivity and the mechanisms.

METHODS

With superior mesenteric arteries from hemorrhagic shock rats, the role of p38 MAPK, ERK, and JNK in the regulation of vascular reactivity following shock and their relationship to myosin light chain (MLC20) phosphorylation-dependent pathway was observed.

RESULTS

ERK, p38 MAPK, and JNK activities in superior mesenteric arteries were increased at early shock and decreased at late shock. Stimulation of MAPKs with angiotensin II (AngII) increased the vascular reactivity, calcium sensitivity, and MLC20 phosphorylation. The increasing effect of AngII on vascular reactivity was antagonized by ERK, p38 MAPK, and JNK inhibitors, while the effect of AngII on calcium sensitivity was only blocked by ERK and p38 MAPK inhibitor, but not by JNK inhibitor. AngII increased the activity of protein kinase C-dependent phosphatase inhibitor of 17-kD (CPI17), integrin-linked kinase (ILK), and zipper-interacting protein kinase (ZIPK), The effect of AngII on CPI17 was blocked by ERK and p38 MAPK inhibitor, while the effect of AngII on ILK and ZIPK was only blocked by ERK inhibitor.

CONCLUSION

MAPKs participated in the regulation of vascular reactivity during shock. ERK and p38 MAPK is mainly through ILK, ZIPK, and CPI17-mediated MLC20 phosphorylation-dependent pathway, while JNK may be involved in the regulation of vascular reactivity by other mechanisms.

Pinacidil pretreatment improves vascular reactivity after shock through PKCα and PKCε in rats

We investigated the beneficial effect of pinacidil pretreatment on vascular reactivity, calcium sensitivity, and animal survival after hemorrhagic shock, its relationship to protein kinase Cα (PKCα), protein kinase Cε (PKCε), and adenosine. Using hemorrhagic shock rats, the protective effects of different extents of pinacidil pretreatment on vascular reactivity and in which the roles of PKCα, PKCε, and adenosine were observed. Pinacidil pretreatment significantly improved shock-induced decrease of vascular reactivity of superior mesenteric artery, which was antagonized by the PKCα antagonist Gö-6976 (5 × 10 mole/L) and PKCε pseudosubstrate inhibitory peptide (1 × 10 mole/L). Pinacidil pretreatment induced the translocation of PKCα and PKCε from the cytoplasm to the membrane. This translocation of PKCα and PKCε was eliminated by adenosine A1 receptor antagonist DPCPX (1 × 10 mole/L). As compared with simple fluid resuscitation, combination with pinacidil pretreatment significantly improved the vascular reactivity and survival rate of hemorrhagic-shocked rats. These results suggested that pinacidil pretreatment could induce good protective effects on vascular reactivity and calcium sensitivity after hemorrhagic shock mainly through the activation of PKCα and PKCε via adenosine A1 receptor, and this protective effect made an important contribution to the overall outcome of shock therapy.

Inhibition of Rho-kinase attenuates endothelial-leukocyte interaction during ischemia-reperfusion injury

Resuscitation from hemorrhagic shock induces endothelial dysfunction and activates inflammatory cascades leading to organ damage. Following restoration of blood flow to ischemic vascular beds, leukocyte-endothelium interactions leading to leukocyte infiltration into the vascular wall occur very early due, in part, to the loss of endothelium-derived nitric oxide (NO). The mechanism by which ischemia-reperfusion injury impairs endothelium-derived NO is not completely understood. We hypothesized that inhibition of Rho-kinase could exert beneficial effects following hemorrhagic shock by preserving endothelial function and attenuating leukocyte trafficking in the microcirculation. Using intravital microscopy, we found that resuscitation from hemorrhage acutely increased the number of rolling and adherent leukocytes in the mouse splanchnic microcirculation. Treatment of mice with the Rho-kinase inhibitor fasudil, markedly attenuated leukocyte-endothelium interaction in response to hemorrhage/reinfusion. The beneficial effect of fasudil was not observed in endothelial nitric oxide synthase (eNOS)(-/-) mice. In conclusion, inhibition of Rho-kinase prevents inflammatory leukocyte trafficking in the microcirculation via an eNOS-dependent mechanism. Our data support a role for Rho-kinase inhibitors in the treatment of ischemia-reperfusion injury.

Physiopathology of shock

Shock syndromes are of three types: cardiogenic, hemorrhagic and inflammatory. Hemorrhagic shock has its initial deranged macro-hemodynamic variables in the blood volume and venous return. In cardiogenic shock there is a primary pump failure that has cardiac output/mean arterial pressure as initial deranged variables. In Inflammatory Shock it is the microcirculation that is mainly affected, while the initial deranged macrocirculation variable is the total peripheral resistance hit by systemic inflammatory response.

Regulatory effect of Rac1 on vascular reactivity after hemorrhagic shock in rats

We used isolated superior mesenteric arteries (SMAs) from hemorrhagic-shock rats and hypoxia-treated vascular smooth muscle cells (VSMCs; mimicking the shock state) to observe the effects of platelet-derived growth factor (PDGF; Rac1 stimulator) and NSC23766 (Rac1 antagonist) on vascular reactivity and the relationship with the Rho kinase-myosin light-chain phosphatase (MLCP) and p21-activated kinase (PAK)-myosin light-chain kinase (MLCK) signal pathway. The results indicated that the contractile responses of the SMAs and VSMCs were significantly increased at early shock or after transient hypoxia. NSC23766 (Rac1 antagonist) further increased, whereas PDGF (Rac1 stimulator) decreased the contractile responses of SMAs and VSMCs. In the late period of shock or prolonged hypoxia, the contractile responses of SMAs and VSMCs were significantly decreased; NSC23766 increased (whereas PDGF further decreased) the contractile response of the SMAs and VSMCs. Activation of Rac1 with PDGF significantly increased the activity of PAK and MLCP, and decreased Rho kinase and MLCK activity and 20-kDa myosin light-chain phosphorylation in VSMCs. The PAK inhibitor PAK-18 significantly antagonized the PDGF-induced decrease in MLCK activity, whereas the Rho kinase antagonist Y-27632 further enforced the PDGF-induced increase in MLCP activity. Simple fluid resuscitation did not improve but in combination with NSC23766 significantly improved vascular reactivity and animal survival at 24 hours. This suggested that Rac1 has an inhibitory effect on vasoreactivity after shock. Rac1-mediated regulation of vascular reactivity is mainly through activation of PAK, inhibition of MLCK and inhibition of Rho kinase, unpack the inhibition of Rho kinase to MLCP. Rac1 may be a potential target to treat vascular hyporeactivity in many critical conditions.

The mechanism by which RhoA regulates vascular reactivity after hemorrhagic shock in rats

RhoA, an important member of the Rho family of GTPases, has been implicated in many cellular processes. Our pilot study found that RhoA participated in the regulation of vascular reactivity after shock, but the mechanism was incompletely understood. Whether RhoA regulates vascular reactivity through the Rho kinase-myosin light-chain phosphatase (MLCP) and Rac1-p21-activated kinase (PAK)-myosin light-chain kinase (MLCK) signaling pathway needs investigation. With isolated, superior mesenteric arteries from hemorrhagic-shock rats and hypoxia-treated vascular smooth muscle cells (VSMCs), the effects of U-46619 (RhoA agonist) and C3 transferase (RhoA antagonist) on vascular reactivity, and the relationship to the Rho kinase-MLCP and Rac1-PAK-MLCK signaling pathways were observed. The vascular reactivity of the superior mesenteric artery and the contractile response of VSMCs to norepinephrine after prolonged hemorrhagic shock and hypoxia (2 h) were significantly decreased. Activation of RhoA with U-46619 significantly increased shock or hypoxia-induced decreased vascular reactivity. These effects of U-46619 were abolished by Y-27632 (Rho kinase inhibitor) and PDGF (Rac1 stimulator). Y-27632 had a stronger antagonistic effect than PDGF. U-46619 increased the activity of Rho kinase and MLCK, enhanced the phosphorylation of 20-kDa myosin light chain, and decreased the activity of Rac1, PAK, and MLCP in VSMCs after hypoxia. Y-27632-antagonized U-46619 induced the decrease of MLCP activity and the increase of 20-kDa myosin light chain phosphorylation. PDGF-antagonized U-46619 induced decrease of PAK activity and increase of MLCK activity. RhoA has an important role in the regulation of vascular reactivity after hemorrhagic shock. The Rho kinase-MLCP and Rac1-PAK-MLCK signal pathways participate in the regulatory process of RhoA. Rho kinase-MLCP may be the main signaling pathway by which RhoA regulates vascular reactivity.

Alcohol does not modulate the augmented acetylcholine-induced vasodilatory response in hemorrhaged rodents

Our previous studies have shown that acute alcohol intoxication (AAI) decreases blood pressure, exacerbates hypotension after hemorrhagic shock, impairs the pressor response to fluid resuscitation, and blunts neuroendocrine activation. We hypothesized that impaired hemodynamic compensation during and after hemorrhagic shock in the acute alcohol-intoxicated host is the result of blunted neuroendocrine activation or, alternatively, of an impaired vascular responsiveness to vasoactive agents. The aim of this study was to examine the effects of AAI, AAI and hemorrhagic shock, and AAI and hemorrhagic shock and resuscitation on reactivity of isolated blood vessel rings to phenylephrine and acetylcholine. Chronically instrumented, conscious male Sprague-Dawley rats (300-350 g) received a primed continuous 15-h intragastric alcohol infusion (2.5 g x kg(-1) + 300 mg x kg(-1) x h(-1)), and time-matched controls received an isocaloric-isovolumic dextrose infusion. At completion of infusions, animals were randomized to sham, 60-min fixed-pressure hemorrhage, or hemorrhagic shock followed by resuscitation with lactated Ringer's solution. At the completion of the experimental protocols, animals were killed, and thoracic aorta and mesenteric artery ring segments (1-2 mm) were prepared and studied in myograph baths. Acute alcohol intoxication did not produce significant alterations in either pressor or dilator responses in aortic or mesenteric rings. These findings suggest that impaired hemodynamic counterregulation during hemorrhagic shock in AAI is not due to decreased vasopressor responsiveness. However, our results suggest a role for accentuated vasodilatory responses that may be central in progression to decompensatory shock.

PKC plays an important mediated effect in arginine vasopressin induced restoration of vascular responsiveness and calcium sensitization following hemorrhagic shock in rats

The present study investigated the mediated effect of protein kinase C (PKC) in arginine vasopressin (AVP)-induced restoration of vascular responsiveness and calcium sensitization following hemorrhagic shock. Using both isolated superior mesenteric artery from hemorrhagic shock rats and hypoxia-treated vascular smooth muscle cell (VSMC), we investigated the roles of PKC-alpha, delta and epsilon isoforms in AVP-induced restoration of vascular reactivity and calcium sensitivity. Meanwhile, effects of their specific inhibitors on the activity of myosin light chain phosphatase (MLCP), myosin light chain kinase (MLCK), and the phosphorylation of myosin light chain (MLC(20)) in VSMC were observed. The results indicated that AVP improved the reactivity of superior mesenteric artery and VSMC to norepinephrine and calcium following hemorrhagic shock and hypoxia. PKC-alpha inhibitor and PKC-epsilon inhibitory peptide antagonized these effects of AVP, while PKC-delta inhibitor only partially antagonized these effects of AVP. AVP up-regulated the expression of PKC-alpha and epsilon in the particulate fractions of hypoxia-treated VSMC with the decrease of the activity of MLCP and the increase of the phosphorylation of MLC(20). These effects of AVP were inhibited by PKC-alpha inhibitor and PKC-epsilon inhibitory peptide, but not by the PKC-delta inhibitor. The results suggested that PKC plays an important role in AVP-induced restoration of vascular reactivity and calcium sensitivity following hemorrhagic shock. PKC-alpha and epsilon may be the main isoforms involved in this process and play effect via MLC(20) phosphorylation dependent mechanism, while PKC-delta may be partially involved in AVP action by other mechanisms.

Regulatory effects of myoendothelial gap junction on vascular reactivity after hemorrhagic shock in rats

Myoendothelial gap junction (MEGJ), one kind of gap junction between vascular endothelial cell and vascular smooth muscle cell, can transmit electrical and chemical signals to keep the electric and machinery activity synchronism of vasculature. After severe trauma or shock, vascular reactivity to vasoconstrictors or vasodilators is greatly reduced. However, whether MEGJ participates in the regulation of vascular reactivity after hemorrhagic shock, what type of MEGJ is involved, and what is the possible mechanism are unknown. With the hemorrhagic shock Sprague-Dawley rats and their superior mesenteric arteries (SMAs), the effects of 18alpha-glycyrrhetic acid, a lipophilic aglycone that disrupts gap junction plaques, on vascular contractile response to norepinephrine (endothelium-independent vascular constrictor), myricetin (endothelium-dependent vasoconstrictor) and relaxation reactivity to sodium nitroprusside (endothelium-independent vasodilator), and acetylcholine (Ach; endothelium-dependent vasodilator) were observed. Meanwhile, the relationship of the mRNA/protein expression of connexins 37, 40, and 43(Cx40 and Cx43) to the changes of vascular reactivity after hemorrhagic shock and the effect of antisense oligodeoxynucleotide of Cx40 or Cx43 on vascular calcium sensitivity and vascular reactivity were investigated. The results indicated that 18alpha-glycyrrhetic acid antagonized myricetin and Ach-induced SMA reactivity, but had no effect on norepinephrine- and sodium nitroprusside-induced vascular response. The mRNA and protein expression of Cx37 and Cx40 of SMA were negatively associated with the vascular reactivity, whereas Cx43 seemed to be a positive relationship to vascular reactivity. Antisense oligodeoxynucleotide of Cx40 significantly increased the calcium sensitivity, myricetin-induced vasoconstriction, and Ach-induced vasodilation, whereas antisense oligodeoxynucleotide of Cx43 depressed them. It was suggested that MEGJ plays an important role in the regulation of endothelium-dependent vascular reactivity after hemorrhagic shock. The involved types were mainly Cx40 and Cx43. The possible mechanism that Cx40/Cx43 regulates the endothelium-dependent vasoconstrictor reactivity may be related to their regulating effects on the calcium sensitivity of vascular smooth muscle cell.

Inhibition of L-type calcium channels in arteriolar smooth muscle cells is involved in the pathogenesis of vascular hyporeactivity in severe shock

The objective was to investigate the changes in the function of L-type calcium (L-Ca2+) channels of arteriolar smooth muscle cells (ASMCs) in the genesis of vascular hyporeactivity during severe shock. A hemorrhagic shock (HS) model was reproduced in rats, and the responsiveness of arterioles in the cremaster muscle to norepinephrine (NE) was measured. The inward currents of L-Ca2+ channel and intracellular concentration of Ca2+ ([Ca2+]i) level in isolated ASMCs were measured using patch clamp and fluorescent probe techniques. The arteriolar vasoreactivity was significantly reduced with a 12.5-fold increase of NE threshold level 2 h post-HS. Meanwhile, the inward currents through L-Ca2+ channels of ASMCs were significantly decreased at different holding potentials, and the maximal inward current was only 26.7% of control value in the shock group. The increased intracellular concentration of Ca2+ level of ASMCs stimulated by NE was reduced to 32.0% of control value 2 h post-HS. Administration of the L-Ca2+ channel stimulator, Bay K8644, partially restored the NE threshold level and transiently increased the mean arterial pressure during HS, lending further support to the importance of ASMC L-Ca2+ channel inhibition in the genesis of low vasoreactivity in vivo during severe shock. Our results suggest that stimulation of L-Ca2+ channels of ASMCs might be a potential therapeutic approach for treatment of refractory hypotension in severe shock.

Mechanisms of Rho kinase regulation of vascular reactivity following hemorrhagic shock in rats

Our previous research showed that Rho kinase took part in the regulation of vascular hyporeactivity after shock. The objective of the present study was to investigate its mechanism. With isolated superior mesenteric artery (SMA) from hemorrhagic shock rats, we studied the relationship of Rho kinase regulating vascular reactivity to calcium sensitivity and myosin light chain phosphatase (MLCP) and myosin light chain kinase (MLCK). The vascular reactivity and calcium sensitivity of SMA were observed by measuring the contraction initiated by accumulative norepinephrine (NE) and calcium under depolarizing condition (120 mM K(+)) with an isolated organ perfusion system. Hypoxia-treated vascular smooth muscle cells (VSMCs) were used to study the effects of Rho kinase on the activity of MLCP and MLCK and the phosphorylation of 20-kDa myosin light chain (MLC(20)). Myosin light chain (20 kDa) phosphorylation of VSMC in mesenteric artery was detected by immunoprecipitation and Western blotting. The activity of MLCP and MLCK was assayed by enzymatic catalysis. The contractile response of VSMC was measured by the ratio of accumulative infiltration of fluorescent isothiocyanate-conjugated bovine serum albumin through transwell. The results indicated that the vascular reactivity and calcium sensitivity of SMA to NE and calcium following hemorrhagic shock and the contractile response of VSMC to NE following hypoxia were significantly decreased. Angiotensin II (Ang-II), the Rho kinase stimulator, significantly improved hypoxia or hemorrhagic shock-induced decrease of vascular reactivity and calcium sensitivity. These effects of Ang-II on vascular reactivity were abolished by Y-27632, the specific Rho kinase inhibitor. Calyculin A, the MLCP inhibitor, further enhanced Ang-II-induced increase of calcium sensitivity, but ML-9, the MLCK inhibitor, had no effect. Further studies showed Ang-II reversed the hypoxia-induced increase of MLCP activity and increased the hypoxia-induced decrease of MLC(20) phosphorylation in VSMC. It was suggested that Rho kinase played an important role in the regulation of vascular reactivity after hemorrhagic shock. The mechanisms may be related to its calcium sensitivity regulation. Rho kinase up-regulates calcium sensitivity of VSMC possibly through inhibiting the activity of MLCP and increasing the phosphorylation of MLC(20).