[Effect of poly-adenosine diphosphate ribosyl-polymerase on vascular hyporeactivity in rats with hemorrhagic shock].

OBJECTIVE: To study the effects of poly-adenosine diphosphate ribosyl-polymerase (PARP) on vascular hyporeactivity during hemorrhagic shock in rats. METHODS: Sprague-Dawley (SD) rats were randomly divided into three groups: shock, 3-aminobenzamide (3-AB) pretreatment+shock, and sham operation. Bleeding from the femoral artery to induce hemorrhagic shock model. The blood pressure changes following 3 microg/kg norepinephrine (NE) injection were observed in vivo. The response of vascular rings of superior mesenteric artery (SMA) to NE was determined ex vivo. The nitrogen monoxide (NO) contents of plasma and tissue homogenate of SMA were measured using the assay kit based on the nitrate reductase reaction. RESULTS: The maximum increase of mean arterial pressure in response to NE immediately following shock in the shock group was significantly lower than in the sham operation group (P<0.01) and the value at 1 hour after blood reinfusion in the shock group was obviously lower than in the 3-AB pretreatment+shock group (P<0.05) and in the sham operation group (P<0.01). The maximum concentration force in the sham operation group [(0.367 1+/-0.221 3)g/mm] was significantly increased than in the 3-AB pretreatment+shock group [(0.286 4+/-0.153 2) g/mm, P<0.05] and in the shock group [(0.185 6+/-0.111 3)g/mm, P<0.01]. The cumulative dose-response curves of SMA to NE shifted to the left, and the contraction force was markedly increased as NE concentration reaching 10(-6), 10(2+) and 10(-5) mol/L in the 3-AB pretreatment+shock group compared to the shock group (all P<0.05). There were no significant difference on plasma NO content among the three groups. However, the NO contents of plasma and tissue homogenate of SMA in the 3-AB pretreatment+ shock group were slightly lower than in the shock group (P>0.05). CONCLUSION: PARP is involved in the vascular hyporeactivity in hemorrhagic-shocked rats.

[Regulatory effect of protein kinase C and protein kinase G on calcium sensitivity of vascular smooth muscle cells following hemorrhagic shock].

OBJECTIVE: To observe the effect of protein kinase C (PKC) and protein kinase G (PKG) on calcium desensitization following hemorrhagic shock in rats. METHODS: The model of hemorrhagic shock was replicated by blood letting and maintaining mean arterial pressure at 40 mm Hg (1 mm Hg=0.133 kPa) for 2 hours. The superior mesenteric artery (SMA) in hemorrhagic shock rats was adopted to assay the calcium sensitivity via observing the contraction initiated by calcium under depolarizing conditions (120 mmol/L K(+)) with isolated organ perfusion system. Meanwhile, the effects of the PMA (PKC agonist), staurosporine (PKC inhibitor), 8Br-cGMP (PKG agonist) and KT-5823 (PKG inhibitor) on calcium sensitivity and the changes in PKC and PKG activities in SMA were observed following hemorrhagic shock. RESULTS: The calcium sensitivity of SMA following hemorrhagic shock was significantly decreased, and the dose-effect curve shifted to the right significantly, maximum energy (Emax) decreased significantly at 2 hours following shock (all P<0.01). The PMA (1 x 10(-7) mol/L) and KT-5823 (1x10(-6) mol/L) significantly increased hemorrhagic shock-induced decrease in calcium sensitivity (P<0.05 or P<0.01). Staurosporine (1 x 10(-7) mol/L) and 8Br-cGMP (1 x 10(-4) mol/L) further decreased calcium sensitivity after shock (P<0.05 or P<0.01). The activity of PKC was decreased and PKG activity was increased 2 hours following shock (P<0.05 and P<0.01), and was positively and negatively correlated with calcium sensitivity of SMA, respectively (both P<0.01). CONCLUSION: PKC and PKG take part in the regulation of calcium sensitivity following hemorrhagic shock. PKC up-regulates calcium sensitivity, and PKG down-regulates calcium sensitivity in vascular smooth muscle cells following hemorrhagic shock.

Gene damages of mitochondrial DNA encoding cytochrome oxidase of intestinal epithelial cells in hemorrhagic shock rats.

OBJECTIVE: To investigate the detrimental effects of hemorrhagic shock on the structure and function of mitochondria DNA (mtDNA) encoding cytochrome oxidase genes in intestinal epithelial cells. METHODS: Wistar rats were used and divided into two groups: hemorrhagic shock group and control group. Hemorrhagic shock model of rats was utilized in this experiment. The mtDNA was extracted from the intestinal epithelial cells and amplified by polymerase chain reaction (PCR) with different primers of cytochrome oxidase (COX I, COX II and COX III). The products of PCR were directly sequenced. RESULTS: Hemorrhagic shock could result in the point mutagenesis in mitochondrial genome encoding cytochrome oxidase (COX I and COX II). There were 4, 4, 22, 16, 35 point mutations in COX I from 5545 to 6838 bp in 5 shocked rats. There were five point mutations in COX II from 7191 to 7542 bp at the site of t7191c, t7212c, a7386g, a7483g, c7542g in 1 shocked rat. There was no mutation found in COX III. CONCLUSIONS: Hemorrhagic shock could significantly induce the damage of the gene of cytochrome oxidase encoded by mtDNA.

Effects of seawater immersion on the functions of mitochondria of myocardium and hepatocyte in hemorrhagic shock rats.

OBJECTIVE: To investigate the effects of seawater immersion on the function of myocardium and hepatocyte mitochondria in experimental hemorrhagic shock rats. METHODS: Twenty-four male Wistar rats were divided into three groups (n=8 in each group): control group, HSL group (hemorrhagic shock group on land) and HSS group (hemorrhagic shock group in seawater). The hemodynamic parameters, activities of H(+)-ATPase (adenosinetriphosphatase), succinate dehydrogenase (SDH) and Ca(2+)-Mg(2+)-ATPase, the calcium contents in myocardium and hepatocyte mitochondria were measured and the changes of proton translocation across the inner mitochondrial membrane were analyzed. RESULTS: The hemodynamic indexes and the activities of H+-ATPase, SDH, Ca(2+)-Mg(2+)-ATPase in HSS group were significantly lower than those in control group and HSL group (P<0.05). In HSS group the calcium levels in tissue and mitochondria of myocardium and hepatocyte were elevated significantly compared with control group and HSL group (P<0.05). There was no significant difference in proton translocation among three groups. CONCLUSIONS: This investigation demonstrates that seawater immersion can aggravate the conditions of hemorrhagic shock rats.

[Changes in systemic and local vascular reactivity in hemorrhagic shock and the therapeutic effect of delta opioid receptor antagonist ICI174,864].

OBJECTIVE: To investigate the changes in systemic and local vascular reactivity following hemorrhagic shock of different severity and the therapeutic effect of alpha opioid receptor antagonist ICI174,864. METHODS: Fifty-six Wistar rats were used in two experiments. In experiment I, 32 rats were equally divided into sham operation group, 1 hour, 2 hours and 3 hours hypotension groups. In the latter groups, rats were bled to a mean arterial blood pressure (MAP) of 40 mm Hg (1 mm Hg=0.133 kPa) and maintained at this level for 1, 2, 3 hours, respectively. The pressor response of blood pressure and the contractile response of superior mesenteric artery (SMA) to norepinephrine(NE, 3 ug/kg) were observed after shed blood was reinfused. In experiment II, 24 rats were divided into shock control, ICI174,864 0.5 mg/kg and 1.0 mg/kg groups. The response of blood pressure and SMA contractility to NE (3 microg/kg) were observed at 1, 2, and 4 hours after ICI174,864 administration. RESULTS: Following hemorrhagic shock, the systemic and local (SMA) vascular responsiveness was significantly decreased significantly and it was time dependent. Shed blood reinfusion alone did not restore the decreased vascular reactivity. ICI174,864 improved the decreased vascular reactivity in dose-dependent manner. CONCLUSION: Hemorrhagic shock can induce systemic and local vascular hyporeactivity. The decreased vascular reactivity is closely associated with the severity and duration of shock. Loss of systemic vascular reactivity parallels to that of the regional vessel. delta opioid receptor antagonist ICI174,864 has some beneficial effect in improving vascular hyporeactivity.

Changes of proton transportation across the inner mitochondrial membrane and H(+)-ATPase in endotoxic shock rats.

OBJECTIVE: To investigate the changes of proton transportation across the inner mitochondrial membrane (IMM) and H(+)-ATPase of hepatocytes in endotoxic shock rats. METHODS: Endotoxin from E. Coil of 5.0 mg/kg or saline of 1 ml/kg was injected into the femoral vein. The rats were sacrificed pre-injection and 1, 3, 5, 8 hours after injection, and plasma and liver tissue samples were collected respectively. The liver tissue samples were used for preparation of mitochondria and submitochondrial particles (SMPs). The proton-translocation of SMPs and H(+)-ATPase, phospholipase A(2) (PLA(2)) activities and malondialdehyde (MDA) content, membrane fluidities of different level of mitochondria membrane and plasma MDA content were assayed. RESULTS: (1) Five hours after E. Coli. O111B4 injection, the maximum fluorescence quenching ACMA after adding ATP, nicotinamide adenin dinucleoacid hydrogen (NADH), and the succinate were significantly decreased (P<0.05). The time of maximum fluorescent quenching and the half time of fluorescent quenching were significantly prolonged (P<0.01), especially when NADH was used as a substrate. (2) The mitochondrial H(+)-ATPase activity was significantly increased at early stage of endotoxic shock (P<0.05), and significantly decreased at late stage of endotoxic shock (P<0.01). (3) The mitochondrial membrane bound PLA(2) activity, plasmal and mitochondrial MDA content were significantly increased and succinate dehydrogenase (SDH) activity of mitochondria decreased markedly in endotoxic shock rats (P<0.05). (4) The mitochondrial membrane fluidity of different lipid regions was decreased, especially in the head of phospholipid. CONCLUSIONS: Proton transportation across IMM and mitochondrial H(+)-ATPase activity are significantly decreased in endotoxic shock.

[Beneficial effect of thyrotropin-releasing hormone in combination with HSD on hemorrhagic shock with pulmonary edema at high altitude in the rat].

OBJECTIVE: To study the effects of thyrotropin-releasing hormone (TRH) in combination with hypertonic saline/dextran (7.5% NaCl + 6% Dextran 40, HSD ) on hemorrhagic shock with pulmonary edema in the rats which were recently brought to high altitude. METHODS: Forty-nine SD rats, transported to Lasa, Tibet, which was 3,760 meters above the sea level, were anesthetized one week later with sodium pentobarbital (30 mg/kg, intraperitoneal). Hemorrhagic shock with pulmonary edema was induced by hemorrhage (50 mm Hg maintained for 1 hour,1 mm Hg=0.133 kPa) plus intravenous injection of oleic acid (50 microl/kg). They were equally divided into seven groups (n=7): normal control, hemorrhagic shock, hemorrhagic shock with pulmonary edema (HSPE), HSPE plus TRH (5 mg/kg), HSPE plus HSD (4 ml/kg), and HEPE plus TRH and HSD in combination. Hemodynamic parameters including mean arterial blood pressure(MAP), left intraventricular systolic pressure (LVSP) and the maximal change rate of intraventricular pressure rise or decline (+/- dp/dt max) were observed at 15, 30, 60 and 120 minutes, blood gases were analyzed at 30 and 120 minutes, and the water content of lung and brain was determined at 120 minutes after drug administration. RESULTS: TRH or HSD used alone or in combination significantly increased MAP, LVSP and +/- dp/dt max (P<0.05 or P<0.01 ), ameliorated acid-base imbalance, and decreased the water content of lung and brain. The effect of the two in combination was superior to either drug used alone. CONCLUSION: TRH in combination with HSD can be used in the treatment of hemorrhagic shock with pulmonary edema at high altitude.

[Effect of different volumes of fluid resuscitation on hemorrhagic shock with pulmonary edema at high altitude in the unacclimated rat].

OBJECTIVE: To study the effects of different volumes of fluid resuscitation on hemorrhagic shock with pulmonary edema at high altitude in the unacclimated rat. METHODS: One hundred and twenty-six SD rats transported to Lasa, Tibet, 3 760 meters above the sea level, were anesthetized one week later with sodium pentobarbital (30 mg/kg, intraperitoneal). Hemorrhagic shock with pulmonary edema model was induced by hemorrhage (50 mm Hg for 1 hour, 1 mmHg=0.133 kPa) plus intravenous injection of oleic acid (50 microl/kg). Experiments were then conducted in two parts. Sixty-three rats in part I were equally divided into nine groups (n=7): normal control, hemorrhagic shock control, hemorrhagic shock with pulmonary edema (HSPE) without fluid infusion, HSPE plus infusing lactated Ringer's solution (LR) with 0.5-, 1-, 1.5-, 2- or 3- fold volume shed blood, and 1 volume of LR plus mannitol (10 ml/kg). Hemodynamic parameters including mean arterial blood pressure (MAP), left intraventricular systolic pressure (LVSP) and the maximal change rate of intraventricular pressure rise or decline (+/- dp/dt max) were observed at 15, 30, 60 and 120 minutes after infusion, blood gases were measured at 30 and 120 minutes after infusion and the water content of lung and brain was determined at 120 minutes after infusion. In part II, additional 63 rats were used to observe the effect of different volumes of fluid resuscitation on survival time of HSPE rats. RESULTS: 0.5 volume of LR infusion significantly improved MAP, LVSP and +/- dp/dt max, prolonged the survival time of HSPE animals (all P<0.01), while it did not increase the water content of lung and brain and had no marked influence on blood gases. One volume of LR infusion slightly improved hemodynamic parameters, prolonged the survival time and increased the water content of lung. More than 1 volume of LR infusion including 1.5-, 2- and 3- fold volume LR deteriorated the hemodynamic parameters and decreased the survival time of shocked animal, meanwhile they apparently increased the water content of lung. One volume of LR plus mannitol (10 ml/kg) infusion did not improve the hemodynamic parameters and blood gases; also it did not decrease the water content of lung. CONCLUSION: The tolerance to fluid infusion for the unacclimated animal subjected to hemorrhagic shock with pulmonary edema at high altitude is significantly decreased. 0.5-1 volume of LR infusion appears to be beneficial effect on resuscitation at high altitude, while over 1 volume of LR infusion would aggravate pulmonary edema and exacerbate fluid resuscitation effect.