Triiodothyronine treatment maintains surfactant synthesis during sepsis.

BACKGROUND. Pulmonary compromise with altered surfactant metabolism is frequently noted during sepsis; triiodothyronine is necessary for normal surfactant synthesis. We evaluated the role of physiologic replacement of triiodothyronine during sepsis-induced hypothyroidism on surfactant synthesis and lung structural integrity. METHODS. Male Sprague Dawley rats (average weight, 330 gm) underwent sham laparotomy or cecal ligation and puncture; treatment was administered to rats that underwent cecal ligation and puncture by Alzet osmotic pump consisting of triiodothyronine (3 ng/hr) or saline control. The rats were killed 24 hours after serum triiodothyronine determination by radioimmunoassay (normal, 60 to 160 ng/dl). Surfactant was obtained by saline lavage. Lipid content was determined by Folch extraction; phospholipid content was verified by chromatography. Blinded histologic analysis of lung confluence and alveolar sparing was done in separate subgroups. Results are +/- SE. RESULTS. Control rats with sepsis were hypothyroid at 24 hours; rats given triiodothyronine were euthyroid (rats that underwent sham laparotomy, 67.7 +/- 4.9 ng/dl; control rats, 37.6 +/- 5.7 ng/dl; and triiodothyronine, 85.7 +/- 19 ng/dl; p less than 0.05 compared with triiodothyronine by analysis of variance). Surfactant production was significantly improved by triiodothyronine compared with control (60.7 +/- 22.6 mg vs 23.2 +/- 11.3 mg; p less than 0.05 by analysis of variance). Lung histologic integrity was maintained by triiodothyronine treatment during sepsis. CONCLUSIONS. Triiodothyronine supplementation may be beneficial in septic-induced pulmonary dysfunction.     

Impaired cell-mediated immunity in experimental abdominal sepsis and the effect of interleukin 2.

A murine model of experimental sepsis, ie, cecal ligation and puncture, was used to determine the potential effects of infection on in vitro cell-mediated immunity. Following cecal ligation and puncture, in vitro responses of mouse splenocytes to mitogens (phytohemagglutinin and concanavalin A), the effects of in vitro interleukin 2 on these responses, and the impact of in vivo interleukin 2 on survival were studied. Compared with controls (sham cecal ligation and puncture), phytohemagglutinin responses 1 day after cecal ligation and puncture were enhanced (43% +/- 17%, n = 9), phytohemagglutinin and concanavalin A responses at day 4 were suppressed (45.5% +/- 4.4% and 57.5% +/- 5.6%), and, by day 7, phytohemagglutinin and concanavalin A responses were approaching values in mice treated by sham cecal ligation and puncture. Suppressed phytohemagglutinin responses at day 4 after cecal ligation and puncture were restored to normal with in vitro interleukin 2 (61,052 +/- 3407 cpm for cecal ligation and puncture and 64,643 +/- 4727 cpm for sham cecal ligation and puncture). Mortalities following cecal ligation and puncture were identical at day 1 after cecal ligation and puncture (6/20) for both interleukin 2- and vehicle-treated groups; thereafter, interleukin 2-treated groups fared better. At day 1 after cecal ligation and puncture, the mean spleen cell phytohemagglutinin response was enhanced (43.8% +/- 17%, n = 9) compared with sham cecal ligation and puncture (= 10). By day 4, the responses to both concanavalin A and phytohemagglutinin were suppressed (45.5% +/- 4.4% and 57.5% +/- 5.6%, respectively). Responses at day 7 approached those of controls given sham cecal ligation and puncture. Sepsis causing a temporary impairment of cell-mediated immunity may be a factor in the frequent coexistence of altered cell-mediated immunity and sepsis, and interleukin 2 may have a role in limiting the adverse effects of sepsis.     

Amino acid uptake in isolated, perfused liver: effect of trauma and sepsis

To examine alterations in amino acid metabolism after trauma and sepsis, male Sprague-Dawley rats underwent no operation (control, CON), celiotomy (trauma, TRA), or cecal ligation and puncture (sepsis, CLP). After 16 hr, plasma amino acid concentrations were determined. A second group of similarly prepared animals underwent isolated liver perfusion, and net amino acid uptake or release was determined over 30 min. Sepsis significantly decreased total amino acid concentration in portal plasma (CON, 3486 +/- 156 nmole/ml; TRA, 3407 +/- 150 nmole/ml; CLP, 2738 +/- 148 nmole/ml). Glutamine concentrations were uniformly lower in portal plasma than in arterial plasma in all states. There were depressed concentrations of the branched chain amino acids (BCAA) in portal plasma after trauma but not sepsis. In the isolated liver perfusion model, a marked increase in amino acid uptake was induced by sepsis (CON, 39.9 +/- 7.9 mumol/g liver protein; TRA, 49.5 +/- 17.3 mumol/g liver protein; CLP, 124 +/- 11 mumol/g liver protein). In addition, there was significantly greater uptake of threonine, asparagine, proline, methionine, tyrosine, and arginine. Although the BCAA isoleucine and valine were taken up to a greater extent in sepsis, the overall BCAA uptake was not significantly greater in sepsis than in control (CON 6.92 +/- 2.15 mumol/g liver protein vs CLP 15.8 +/- 1.9 mumol/g liver protein). The greatest increase in uptake following sepsis was among the gluconeogenic precursor amino acids alanine, glycine, threonine, and serine (CON, 27.0 +/- 4.2 mumol/g liver protein, TRA, 38.8 +/- 8.9 mumol/g liver protein; CLP, 62.8 +/- 6.0 mumol/g liver protein).(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased synthesis of secreted hepatic proteins during abdominal sepsis

To study the effect of intraabdominal sepsis on hepatic protein synthesis, male Sprague-Dawley rats underwent celiotomy with either cecal ligation and puncture (CLP) or sham operation. Eight and sixteen hours later total hepatic protein synthesis was measured by flooding dose technique. Specific synthetic rates of structural or secreted hepatic proteins were further studied 16 hr after CLP in an isolated perfused liver model. Total hepatic protein synthesis was significantly elevated at 16 hr (59 +/- 6%/day vs 37 +/- 6%/day, P less than 0.05), but not 8 hr post-CLP. Structural hepatic protein synthesis was unchanged after CLP; however, the synthetic rates of the acute-phase secretory proteins alpha 1-acid glycoprotein, transferrin and complement component C3 were significantly increased 16 hr after CLP. However, the albumin synthetic rate was not increased during sepsis. We conclude that sepsis causes augmentation of hepatic protein synthesis primarily to increase acute-phase proteins for host defense.     

Cecal ligation and puncture as a model of sepsis in the rat: influence of the puncture size on mortality, bacteremia, endotoxemia and tumor necrosis factor alpha levels

BACKGROUND: Cecal ligation and puncture is a widely used experimental model of sepsis. AIM OF THE STUDY: The present study was aimed to evaluate the influence of the size of the cecal puncture on mortality, bacteremia, endotoxemia and plasma TNF-alpha levels. MATERIALS AND METHODS: Female Sprague-Dawley rats underwent cecal ligation and puncture, divided into the following groups, defined by the diameter of the cecal puncture: 0.5-cm blade incision (n = 25), 13-gauge (n = 25), 16-gauge (n = 25), 18-gauge puncture (n = 25) and 4 punctures with a 22-gauge needle (n = 25). A sham operation was performed in another 25 rats. Three animals of each group were sacrificed 5 h after the procedure for blood cultures as well as determination of plasma endotoxin and TNF-alpha. The remaining animals were followed up for a week after cecal ligation and puncture for evaluation of mortality. RESULTS: Five hours after cecal ligation and puncture, bacteremia was present in all animals, independently of the puncture size. Endotoxemia and plasma TNF levels tended to increase along with the diameter of the cecal puncture. Mortality gradually increased with the puncture size, from 27% with a 22-gauge needle to 95% with the blade incision. CONCLUSIONS: The severity of sepsis obtained with cecal ligation and puncture in rats can be easily modulated varying the size of the puncture.     

Insulin resistance and depressed gluconeogenic capability during early hyperglycemic sepsis

The present study was performed to determine whether insulin resistance, independent of the prevailing hormonal milieu, occurs in the liver during sepsis. To determine this, sepsis was produced in rats by cecal ligation and puncture (CLP). Six hours later, when the rats were in the early hypermetabolic phase of sepsis, the livers were isolated and perfused with Krebs-HCO3 buffer using a nonrecirculating system. The effects of various concentrations of insulin on the gluconeogenic response to lactate and phenylephrine stimulation were determined. In the absence of insulin and phenylephrine, there was no difference in the rates of glucose production from lactate between septic and sham-operated rats. The gluconeogenic response to phenylephrine stimulation was, however, significantly depressed in the livers from septic rats. Addition of 50 microU insulin/ml resulted in an inhibition of the phenylephrine-stimulated glucose release from livers from sham-operated rats. This inhibition was maximal at 100 microU insulin/ml. In contrast, significant inhibition of phenylephrine-stimulated glucose release from livers from septic rats was only observed in the presence of 2,000 microU insulin/ml. These results demonstrate that even during the early, hypermetabolic phase of sepsis, depressed hormonally stimulated hepatic gluconeogenic capability occurs. In addition, livers from septic rats exhibited a resistance to the effects of insulin on gluconeogenesis. This resistance may account, at least in part, for accelerated gluconeogenesis in spite of hyperinsulinemia in early sepsis.     

Effective hepatic blood flow and hepatic bioenergy status in murine peritonitis

To assess the effects of sepsis on effective hepatic blood flow (EHBF) and hepatic tissue bioenergy status 250-350 g rats underwent either sham laparotomy or cecal ligation and perforation (CLP). At 5-, 10-, and 20-hr intervals cardiac output (CO), EHBF, and tissue adenine nucleotide levels were measured. CLP rats showed a hyperdynamic response to sepsis at 20 hr, with CO increased by 25% over sham rats. At all time intervals studied EHBF was decreased and at 20 hr it was maximally decreased by 35%. Hepatic energy charge (HEC) was calculated from tissue adenine nucleotide measurements. HEC was not statistically different in sham and CLP rats at 5 hr and was 11 and 9% reduced from sham levels in CLP rats at 10 and 20 hr, respectively. Thus, EHBF is decreased very early in sepsis; before any changes in hepatic bioenergy status are noted. In this hyperdynamic model of sepsis EHBF is decreased early and decreases progressively with time which may contribute to the significant decrease in HEC that is demonstrated.     

Corticosterone alone does not explain increased muscle proteolysis in septic rats

The mediators and mechanisms of muscle proteolysis in sepsis are not fully known. We investigated the role of corticosterone in increased muscle proteolysis during sepsis in rats. In one series of experiments, plasma corticosterone and total and myofibrillar protein breakdown rates, determined in incubated extensor digitorum longus muscles as release of tyrosine and 3-methylhistidine, respectively, were measured 16 hr after sham operation (control) or cecal ligation and puncture (sepsis). In other experiments, corticosterone (10 mg/100 g body wt) was injected subcutaneously twice over 16 hr; thereafter, plasma hormone levels and muscle protein breakdown rates were determined. Plasma corticosterone was increased from 14 +/- 1 micrograms/dl in control rats to 38 +/- 8 micrograms/dl in septic rats and total and myofibrillar protein breakdown rates were increased by 99 and 326%, respectively, in muscles from septic rats. When administration of corticosterone resulted in plasma levels similar to those observed in septic rats, total or myofibrillar protein breakdown rates were not altered. The results suggest that corticosterone alone is not responsible for increased muscle proteolysis in septic rats. The data, however, do not rule out the possibility that glucocorticoids may be a cofactor to some other substance or substances in the induction of muscle proteolysis during sepsis.     

Sepsis alters skeletal muscle energetics and membrane function.

The effects of sepsis on skeletal muscle energetics and membrane function are poorly understood, and the time course of changes in energy metabolism are unclear. To clarify these relationships, high energy phosphate ratios, intracellular pH, and phosphocreatine breakdown rates were measured in vivo in the gastrocnemius muscle of adult male Wistar rats after cecal ligation and puncture or sham operation with 31P magnetic resonance spectroscopy. Adenosine triphosphate (ATP) concentration and Na(+)-K+ ATPase and creatine kinase activities were determined in vitro. Within 24 hours, Na(+)-K+ ATPase activity increased by 60% in rats with cecal ligation and puncture, all of which had positive bacterial cultures, as compared to none of the sham-operated controls. Phosphocreatine/ATP ratios decreased by 20% in association with a quantitatively similar increase in phosphocreatine breakdown (9.7 +/- 0.5 vs 11.9 +/- 0.5 mumoles/gm wet wt/sec; p = 0.01). ATP concentrations were maintained, and intracellular pH did not change significantly. In this model, changes in phosphocreatine breakdown were not related to total creatine kinase activity, which did not change significantly, or increases in adenosine 5'-diphosphate (ADP) concentration (62 +/- 8 vs 92 +/- 8 mumols/L; p = 0.02). Thus, in early sepsis before a measurable decrease in pH occurs, ATP is utilized at an increased rate to help maintain ionic balance and/or to support other metabolic processes. Phosphocreatine stores are used to buffer ATP concentrations.     

Gluconeogenesis in tumor-influenced hepatocytes

The growth of a tumor leads to alterations in host carbohydrate metabolism. In this study we examined gluconeogenic capacity and amino acid transport in tumor-influenced and control rat hepatocytes. Serum glucose level decreased with increasing tumor burden and a significant correlation (r = -0.80) was observed. Hepatic glycogen content was similar in both groups after an overnight fast. Endogenous glucose production was 27% higher in tumor-influenced hepatocytes. The presence of 10mM of alanine led to 72% stimulation of gluconeogenesis in tumor-influenced hepatocytes as compared to 48% stimulation in control hepatocytes. The same trends were present when lactate was used as a substrate. Alanine transport into the cells was increased in tumor-influenced hepatocytes by 55% +/- 5% at a physiologic level of substrate. In conclusion, gluconeogenesis from alanine and lactate is significantly increased in tumor-influenced hepatocytes despite decreased serum glucose levels. This is associated with increased gluconeogenic capacity and accelerated alanine transport.     

Absence of intestinal bile promotes bacterial translocation.

Previously, the authors documented that extrahepatic biliary obstruction promotes the systemic translocation of bacteria from the intestine to visceral tissues. The current experiments were performed to determine whether it was the absence of intestinal bile or the presence of biliary obstruction that promoted bacterial translocation. Four groups of rats were studied: 1) nonoperated controls (n = 20), sham common bile duct-ligated (n = 22), common bile duct-ligated (n = 25), and common bile duct-diverted (choledochovesical bypass) (n = 23). The sham-ligated group underwent laparotomy and manipulation of the portal region; whereas the ligated group had their common bile ducts ligated, while the choledochovesical group had a silastic tube placed from the common bile duct to the bladder. Seven days later, at death, the incidence of bacterial translocation was higher in the groups of rats subjected to common bile duct ligation (41%) or diversion (32%) than in the control (3%) or sham-ligated (5%) groups (P less than 0.05). Histologic sections of ileums of ligated and diverted animals both showed subepithelial edema. These findings suggest that it is primarily the absence of bile in the intestine that promotes mucosal injury and bacterial translocation and not biliary obstruction.     

Adenoviral Vector Transfection into the Pulmonary Epithelium after Cecal Ligation and Puncture in Rats

Background: Adenoviral-targeted gene delivery to respiratory epithelium can augment production of specific proteins. Therefore, it may be valuable in treating the acute respiratory distress syndrome. The authors tested the hypothesis that adenoviral vector uptake after cecal ligation and double puncture in rats, an animal model of the acute respiratory distress syndrome, is higher than that observed in controls that did not undergo operation ("nonoperated") or those that underwent a sham operation ("sham-operated").

Methods: Adenoviruses expressing green fluorescent protein or Lac-Z were delivered into the lungs of anesthetized rats via tracheal catheter. Animals were killed 24 or 48 h later. Histopathology and green fluorescent protein expression were examined using light of fluorescence microscopy. Cellular localization of Lac-Z was determined with electron microscopy or semithin sectioning. Viral receptor density and localization were determined using immunoblotting and immunohistochemistry.

Results: After cecal ligation and double puncture, rats were hypoxic and tachypneic. Alveoli were segmentally consolidated, contained proteinaceous debris and neutrophils, and had thickened septa. Administration of adenoviruses to rats that were sham-operated or underwent cecal ligation and double puncture resulted in high levels of marker protein expression in cells lining alveoli. Use of 3 x 1011 plaque-forming units instead of 3 x 1012 plaque-forming units resulted in similar levels of green fluorescent protein expression with negligible viral-mediated lymphocytic infiltration. Semithin section and electron microscopy revealed expression primarily localized to type II alveolar cells. Abundance of [alpha]v[beta]3 integrins and human coxsackie-adenovirus receptor (receptors that modulate viral attachment and internalization) was increased after cecal ligation and double puncture, predominantly in type II pneumocytes.     

Studies on the possible role of thyroid hormone in altered muscle protein turnover during sepsis.

Five days after thyroidectomy (Tx) or sham-Tx in young male Sprague-Dawley rats, sepsis was induced by cecal ligation and puncture (CLP). Control animals underwent laparotomy and manipulation of the cecum without ligation or puncture. Sixteen hours after CLP or laparotomy, protein synthesis and degradation were measured in incubated extensor digitorum longus (EDL) and soleus (SOL) muscles by determining rate of 14C-phenylalanine incorporation into protein and tyrosine release into incubation medium, respectively. Triiodothyronine (T3) was measured in serum and muscle tissue. Protein synthesis was reduced by 39% and 22% in EDL and SOL, respectively, 16 hours after CLP in sham-Tx rats. The response to sepsis of protein synthesis was abolished in Tx rats. Protein breakdown was increased by 113% and 68% in EDL and SOL, respectively, 16 hours after CLP in sham-Tx animals. The increase in muscle proteolysis during sepsis was blunted in hypothyroid animals and was 42% and 49% in EDL and SOL, respectively. T3 in serum was reduced by sepsis, both in Tx and sham-Tx rats. T3 in muscle, however, was maintained or increased during sepsis. Abolished or blunted response of muscle protein turnover after CLP in hypothyroid animals may reflect a role of thyroid hormones in altered muscle protein metabolism during sepsis. Reduced serum levels of T3, but maintained or increased muscle concentrations of the hormone, suggests that increased T3 uptake by muscle may be one mechanism of low T3 syndrome in sepsis, further supporting the concept of a role for thyroid hormone in metabolic alterations in muscle during sepsis.     

Adenoviral vector transfection into the pulmonary epithelium after cecal ligation and puncture in rats

BACKGROUND: Adenoviral-targeted gene delivery to respiratory epithelium can augment production of specific proteins. Therefore, it may be valuable in treating the acute respiratory distress syndrome. The authors tested the hypothesis that adenoviral vector uptake after cecal ligation and double puncture in rats, an animal model of the acute respiratory distress syndrome, is higher than that observed in controls that did not undergo operation ("nonoperated") or those that underwent a sham operation ("sham-operated"). METHODS: Adenoviruses expressing green fluorescent protein or Lac-Z were delivered into the lungs of anesthetized rats via tracheal catheter. Animals were killed 24 or 48 h later. Histopathology and green fluorescent protein expression were examined using light of fluorescence microscopy. Cellular localization of Lac-Z was determined with electron microscopy or semithin sectioning. Viral receptor density and localization were determined using imunoblotting and immunohistochemistry. RESULTS: After cecal ligation and double puncture, rats were hypoxic and tachypneic. Alveoli were segmentally consolidated, contained proteinaceous debris and neutrophils, and had thickened septa. Administration of adenoviruses to rats that were sham-operated or underwent cecal ligation and double puncture resulted in high levels of marker protein expression in cells lining alveoli. Use of 3 x 10(11) plaque-forming units instead of 3 x 10(12) plaque-forming units resulted in similar levels of green fluorescent protein expression with negligible viral-mediated lymphocytic infiltration. Semithin section and electron microscopy revealed expression primarily localized to type II alveolar cells. Abundance of alpha(v)beta3 integrins and human coxsackie-adenovirus receptor (receptors that modulate viral attachment and internalization) was increased after cecal ligation and double puncture, predominantly in type II pneumocytes. CONCLUSIONS: Cecal ligation and double puncture induces histologic and functional changes consistent with the acute respiratory distress syndrome, increases surface expression of viral receptors, and enhances adenoviral-mediated gene transfer.     

Hypothyroidism abolishes the hyperdynamic phase and increases susceptibility to sepsis

To evaluate the role of thyroid hormones in sepsis, 250-400 g rats were surgically thyroidectomized and 2-6 weeks later sepsis was produced by cecal ligation and puncture (CLP). In normal rats, total body O2 consumption (VO2) increased by 12.8% (P less than 0.05) in early sepsis (6 hr after CLP) and decreased slightly in late sepsis (16 hr after CLP). In hypothyroid (HT) rats, VO2 was depressed by 19.8% (P less than 0.05) in early sepsis and further decreased to 46.7% (P less than 0.001) of preoperative levels in late sepsis. Hepatic blood flow increased in early sepsis in normal rats but was unchanged in HT rats. The normal hyperglycemic response to early sepsis was also absent in HT rats. The respiratory control ratio (RCR) of isolated mitochondria with succinate was not increased in HT rats in early sepsis. In late sepsis, hypothyroid animals showed further decreases in VO2 and mitochondrial RCR, and, in contrast to normal rats, showed no change in blood glucose levels. Survival (5 days) following late sepsis in normal, HT, and HT rats given daily ip injections of thyroxine (30 micrograms/kg) were 65.2% (15/23), 30% (6/20) (P less than 0.025), and 77.1% (14/18), respectively. Thus, absence of thyroid hormone abolishes the hyperdynamic phase of sepsis and significantly increases mortality in sepsis, and thyroxine replacement following thyroidectomy prevents the increased mortality from sepsis.     

In vivo phosphorus 31 magnetic resonance spectroscopy of rat hind limb skeletal muscle during sepsis

High-energy phosphate metabolism in skeletal muscle is altered during sepsis, although the chronology of events is uncertain. Phosphorus 31 magnetic resonance spectroscopy was used to measure changes in muscle energy stores of the left hind limb musculature of adult male rats during sepsis. Following control scans, cecal ligation and puncture were performed and scanning was repeated 6, 24, and 48 hours after surgery. The ratios of phosphocreatine (PCr) to inorganic phosphate (Pi), a measure of energy stores, and adenosine triphosphate (ATP) to Pi ratio, a measure of the energy available for immediate use, were determined from peak heights. Intracellular pH was calculated using the distance between Pi and PCr peaks. In surviving animals, a 40% decrease in PCr/Pi ratio (+/- SEM) was observed by 24 hours (22.3 +/- 3.0 at time 0 vs 13.3 +/- 2.8 at 24 hours), whereas energy availability (beta-ATP/Pi) was statistically unchanged (18.2 +/- 2.2 at time 0 vs 15.2 +/- 1.2 at 48 hours). Intracellular pH did not change. Both PCr/Pi and ATP/Pi ratios were inversely correlated with time. In this model of documented peritonitis, skeletal muscle energy metabolism is rapidly altered following severe infection, and these changes can be detected using 31P magnetic resonance spectroscopy.     

Open peritoneal management in murine peritonitis

Open management of the peritoneal cavity with mesh insert in severe peritonitis has been the subject of favorable clinical reports. The present study was undertaken to develop an animal model suitable for investigation of this technique. Peritonitis was induced in anesthetized rats using the technique of cecal puncture following nonobstructing cecal ligation. A pilot study with this technique did not result in either intestinal distention or edema. Therefore, distal ileal ligation was added to duplicate the clinical findings associated with diffuse peritonitis. Twenty animals treated in this manner underwent standard abdominal wall closure and were simply observed for 96 hours. This produced a 15 per cent mortality at 24 hours, 65 per cent at 48 hours, 70 per cent at 72 hours, and 80 per cent at 96 hours. A second group underwent sham laparotomy only (n = 5) with a resultant 100 per cent survival. Based on these preliminary findings, two study groups were defined. Animals in both groups had cecal ligation and puncture and ileal ligation performed. Group I (n = 22) animals underwent re-laparotomy 24 hours later with primary fascial closure, while group II (n = 23) animals underwent re-laparotomy at 24 hours with placement of a standardized Dexon mesh insert covered by a superficial polyethylene film to prevent fluid loss. No animals received antibiotics. Cumulative mortalities in group I were 77, 90, 90, and 90 per cent at 24, 48, 72, and 96 hours after reoperation. In group II mortalities were found to be 48, 57, 61, and 70 per cent at 24, 48, 72, and 96 hours.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hepatic protein synthesis in a modified septic rat model

The aim of this study was to develop a reproducible and sustained sepsis model in rats, lasting 3-4 days and characterized by appropriate metabolic changes, including increased hepatic protein synthesis, consistent with an acute-phase response. The rat cecal ligation and puncture (CLP) model was modified by decreasing the size and number of cecal punctures and increasing fluid resuscitation, which resulted in a 60% survival rate at 96 hr compared to 20% for standard CLP. Cultures of blood and peritoneal fluid 96 hr following induction of sepsis were positive in all septic animals with a mixed aerobic and anaerobic flora but with predominant growth of Escherichia coli. Septic rats demonstrated increased serum lactate levels and leukocytosis, while serum glucose and resting energy expenditure were not different from controls. Hepatic protein synthesis, measured in vivo by flooding dose technique, was increased by 74% in septic animals. Synthesis of the acute-phase proteins alpha 1-acid glycoprotein, complement component C3, and transferrin, measured by incorporation of [14C]leucine into proteins during a 120-min isolated liver perfusion, was increased twofold in septic animals. The present modified CLP model in rats may be useful in studies on the regulation of acute-phase protein synthesis during prolonged sepsis and in experiments aimed at modulating the septic response in liver by different treatments.     

Effect of propranolol on nitrogen and energy metabolism in sepsis

Pharmacologic therapy designed to block adrenergic activity or alter hormonal milieu may modulate energy and protein metabolism in stress. The metabolic effects of propranolol (beta adrenergic receptor blocker) in sepsis was investigated in 22 well-nourished rats that underwent superior vena caval cannulation, cecal ligation, and puncture. Animals were randomly assigned to receive either a continuous infusion of 0.7 mg/day of propranolol combined with parenteral nutrition (n = 11) or parenteral nutrition alone (n = 11). Both groups received isocaloric, isonitrogenous, isovolemic, parenteral nutrition post-operatively for 24 hr. Nitrogen balance was better for the propranolol group than for the control group (+743 +/- 84 mg/kg/day versus +300 +/- 63 mg/kg/day, respectively, P less than 0.05). A significant difference between the pharmacologic therapy and control groups was noted for urinary 3-methylhistidine excretion versus control (0.99 +/- 0.08 micrograms/kg/day versus 7.5 +/- 0.37 micrograms/kg/day, respectively, P less than 0.01). Measured energy expenditure was similar for both pharmacologic therapy and control groups (149 +/- 20 kcal/kg/day versus 134 +/- 11 kcal/kg/day, respectively, P = N.S.). No statistically significant difference was demonstrated for 24-hr survival between propranolol and control groups (73 and 64%, respectively). Continuous, low-dose propranolol promotes nitrogen retention and decreases 3-methylhistidine excretion without altering energy expenditure in parenterally fed septic rats.