Metabolic control of hepatic gluconeogenesis in response to sepsis

The regulation of hepatic gluconeogenesis was studied in rats made septic by cecal-ligation and puncture technique. Blood glucose was not significantly different in septic rats, but lactate, pyruvate, and alanine were markedly increased. Conversely, blood ketone body concentrations were markedly decreased in septic rats. Both plasma insulin and glucagon were markedly elevated in septic rats. The maximal activities of glucose 6-phosphatase, fructose 1,6-biphosphatase, pyruvate carboxylase, and phosphenolpyruvate carboxykinase were decreased in livers obtained from septic rats suggesting a diminished hepatic gluconeogenesis. Hepatic concentrations of lactate, pyruvate, and other gluconeogenic intermediates were markedly increased in septic rats, whereas those of fructose 2,6-bisphosphate and acetyl-CoA were decreased. The rate of gluconeogenesis from added lactate, pyruvate, alanine, and glutamine was decreased in isolated incubated hepatocytes from septic rats. It is concluded that the diminished capacity of hepatic gluconeogenesis of septic rats could be the result of changes in the maximal activities or regulation of key nonequilibrium gluconeogenic enzymes or both but do not exclude other factors (e.g., toxins).     

Metabolic regulation of renal gluconeogenesis in response to sepsis in the rat

1. The regulation of renal gluconeogenesis was studied in rats made septic by a caecal ligation and puncture technique. 2. Blood glucose concentrations were not markedly different in septic rats, but lactate, pyruvate and alanine concentrations were markedly increased, compared with sham-operated rats. Conversely, blood ketone body concentrations were significantly decreased in septic rats. Both plasma insulin and glucagon concentrations were markedly elevated in response to sepsis. 3. The maximal activities of glucose-6-phosphatase (EC 3.1.3.9), fructose-1,6-bisphosphatase (EC 3.1.3.11), pyruvate carboxylase (EC 6.4.1.1) and phosphoenolpyruvate carboxykinase (EC 4.1.1.49) were markedly decreased in kidneys obtained from septic rats, suggesting diminished renal gluconeogenesis. 4. Renal concentrations of lactate, pyruvate and other gluconeogenetic intermediates were markedly elevated in septic rats, whereas those of acetyl-CoA and fructose 2,6-bisphosphate were decreased and unchanged, respectively. 5. The rate of gluconeogenesis from added lactate, pyruvate and glycerol was decreased in isolated incubated renal tubules from septic rats. 6. Sepsis decreased the arteriovenous concentration difference for glucose, lactate, and alanine. Septic rats showed decreased net rates of glucose production and net rates of removal of lactate and alanine as compared with sham-operated controls. 7. It is concluded that the diminished capacity for renal gluconeogenesis in septic rats could be the result of changes in the maximal activities or regulation of key non-equilibrium gluconeogenic enzymes or both, but the effect of other factors (e.g. toxins) has not been excluded.     

Regulation of gluconeogenesis and ketogenesis during rest and exercise in diabetic subjects and normal men.

The splanchnic-hepatic metabolism of glucose, lactate, pyruvate, alanine, glycerol, non-esterified fatty acids (NEFA), ketone bodies and oxygen were investigated in five normal men and six juvenile diabetic subjects at rest and during exercise after an overnight fast. A linear relationship was found between load (arterial concentration multiplied by hepatic blood flow) and splanchnic-hepatic uptake of lactate, pyruvate, glycerol and NEFA. The uptake of alanine was highly sensitive to load, but was also regulated by the concentration of hepatic venous glucagon. The uptake of pyruvate was high in exercising diabetic subjects, who had a high lactate/pyruvate concentration ratio in hepatic venous blood. The rate of uptake of the total measured gluconeogenic precursors was significantly higher in the diabetic group at a given load. The rate of ketogenesis was linearly related to the NEFA load in both groups; however, the rate of ketogenesis was twofold at a given load in the diabetic group. The highest rates of ketogenesis were found coincident with the highest concentrations of glucagon in hepatic venous blood. The observed antiketogenic effect of exercise was due to a decreased load of NEFA, mainly caused by a decrease in the hepatic blood flow.     

Maximal activity of phosphate-dependent glutaminase and glutamine metabolism in septic rats

The activity of phosphate-dependent glutaminase and glutamine metabolism by tissues known markedly to utilize or synthesize glutamine (or both) were studied in rats made septic by cecal ligation and puncture technique and compared with the same measures in rats that underwent sham operation (laparotomy). Blood glucose level was not markedly different in septic rats, but lactate, pyruvate, alanine, and glutamine levels were markedly increased. Conversely, blood ketone body concentrations were significantly decreased in septic rats. Both plasma insulin and glucagon levels were markedly elevated in response to sepsis. The maximal activity of phosphate-dependent glutaminase was decreased in the small intestine, increased in the kidney and mesenteric lymph nodes, and unchanged in the liver of septic rats. Arteriovenous concentration difference measurements across the gut showed a decrease in the net glutamine removed from the circulation in septic rats. Arteriovenous concentration difference measurements for glutamine showed that both renal uptake and skeletal muscle release of the amino acid were increased in response to sepsis, whereas measurements across the hepatic bed showed a net uptake of glutamine in septic rats. Enterocytes isolated from septic rats exhibited a decreased rate of utilization of glutamine and production of glutamate, alanine, and ammonia, whereas lymphocytes isolated from septic rats showed an enhanced rate of utilization of glutamine and production of glutamate, aspartate, and ammonia. It is concluded that, during sepsis, glutamine uptake and metabolism are enhanced in renal and lymphoid tissue but decreased in that of the small intestine, with increased rates of release by skeletal muscle; however, the liver appears to utilize glutamine in septic rats.     

Hepatic Ketogenesis and Gluconeogenesis in Humans

Splanchnic arterio-hepatic venous differences for a variety of substrates associated with carbohydrate and lipid metabolism were determined simultaneously with hepatic blood flow in five patients after 3 days of starvation.Despite the relative predominance of circulating beta-hydroxybutyrate, the splanchnic productions of both beta-hydroxybutyrate and acetoacetate were approximately equal, totaling 115 g/24 h. This rate of hepatic ketogenesis was as great as that noted previously after 5-6 wk of starvation. Since the degree of hyperketonemia was about threefold greater after 5-6 wk of starvation, it seems likely that the rate of ketone-body removal by peripheral tissues is as important in the development of the increased ketone-body concentrations observed after prolonged starvation as increased hepatic ketone-body production rate.Splanchnic glucose release in this study was 123 g/24 h, which was less than that noted previously after an overnight fast, but was considerably more than that noted during prolonged starvation. Hepatic gluconeogenesis was estimated to be 99 g/24 h, calculated as the sum of lactate, pyruvate, glycerol, and amino acid uptake. This was greater than that observed either after an overnight fast or after prolonged starvation. In addition, a direct relationship between the processes of hepatic ketogenesis and gluconeogenesis was observed.     

Ketogenesis during sepsis in relation to hepatic energy metabolism

The concentrations of acetoacetate, beta-hydroxybutyrate, and adenine nucleotides, and the mitochondrial phosphorylative activities, induced by cecal ligation and punctured in the liver of septic rats, were determined. The concentrations of glucose, free fatty acids (FFA), and free amino acids in arterial blood were also studied along with ketone body concentrations. Hepatic energy charge levels decreased from 0.84 to 0.77 at 12h after the induction of sepsis (P less than 0.01) and to 0.60 at 18h (P less than 0.001). Mitochondrial phosphorylative activity was enhanced at 6h (P less than 0.001) and decreased at 18h later. Ketone body concentrations in the liver and the arterial blood decreased concomitant with the decrease in hepatic energy charge. The mitochondrial redox state increased significantly at 12 and 18h after the induction of sepsis (P less than 0.01) concomitant with a marked decrease in the concentrations of ketone bodies (P less than 0.01). Blood glucose levels remained within normal limits except for a transient increase at 6h, but plasma FFA levels decreased (P less than 0.01). The plasma concentrations of aromatic amino acids (P less than 0.001), proline, and alanine (P less than 0.05) increased slightly at 18h. It is suggested that the ketogenic capacity of the liver is inhibited during sepsis, but that the liver maintains gluconeogenesis at relatively normal levels until a more advanced stage of sepsis.     

Effect of hyperthyroidism on hepatic lipogenesis in rats: studies in vivo and in vitro

Lipogenic rates (measured with 3H2O) in hepatocytes from fed or starved euthyroid rats were similar in magnitude to those measured in livers in vivo. Hepatic lipogenesis in vivo in fed triiodothyronine (T3)-treated rats was greater than in fed control rats, but rates in vitro were only 16% of those of control rats. It is concluded that hepatic lipogenesis in vivo in T3-treated rats utilizes precursors from extrahepatic tissues. Glycogen depletion of hepatocytes from fed control rats decreased lipogenesis, and rates were then similar to those in hepatocytes from fed T3-treated rats. Addition of lactate (2 mmol/l) and pyruvate (0.2 mmol/l) had little stimulatory effect on lipogenesis in hepatocytes from fed control rats, but increased lipogenesis in glycogen-depleted hepatocytes (by 86%), hepatocytes from starved rats (by 25%) and hepatocytes from T3-treated rats (by 60%). In the presence of lactate and pyruvate, 3-mercaptopicolinate (3-MPA) (an inhibitor of gluconeogenesis) did not affect lipogenesis in hepatocytes from fed control rats but substantially increased lipogenesis in hepatocytes from starved euthyroid rats or fed hyperthyroid rats. Thus, in hepatocytes from starved euthyroid rats or fed hyperthyroid rats gluconeogenesis competes with lipogenesis for available precursors (lactate and pyruvate). In contrast, in fed rats carbon flux is predominantly towards lipogenesis. Effects of 3-MPA in the presence of lactate and pyruvate were much less in glycogen-depleted cells from fed rats than in hepatocytes from starved or T3-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of dopexamine on hepatic metabolic activity in patients with septic shock

Hepato-splanchnic metabolic activity is seen to be related to regional blood flow and oxygen/substrate availability in patients with sepsis. Catecholamines, which may modulate metabolic activity perse, are common to stabilize hemodynamics. We studied the effect of a dopexamine-induced increase in splanchnic blood flow (Qspl) on regional metabolic rate in 10 patients with septic shock requiring norepinephrine to maintain mean arterial pressure (>60 mmHg). Splanchnic blood flow was determined using the indocyanine-green method with hepatic venous sampling. We determined the hepato-splanchnic lactate, pyruvate, alanine, and glutamine turnover and the lactate/pyruvate and ketone body ratio as well as the endogenous glucose production (EGP) using the stable isotope approach. Qspl increased from 0.86 (0.79-1.15) to 0.96 (0.92-1.33) L/min/m2, not influencing any parameter of metabolic activity. We speculate that this finding is due to altered beta-adrenoreceptor-mediated thermogenic effects due to the interplay of different beta-sympathomimetics at the receptor site.     

Glutamine and alanine metabolism in lungs of septic rats.

1. The metabolism of glutamine and alanine in the lung was studied in rats made septic by a caecal ligation and puncture technique. 2. The blood glucose concentration was not significantly different in septic rats, but blood pyruvate, lactate, glutamine and alanine concentrations were markedly increased as compared with sham-operated rats. Conversely, blood ketone body and plasma cholesterol concentrations were significantly decreased in septic rats. Both plasma insulin and plasma glucagon concentrations were markedly elevated in response to sepsis. Sepsis resulted in a negative nitrogen balance. 3. Sepsis increased the rates of production of glutamine (52.5%, P less than 0.001), alanine (38.9%, P less than 0.001) and glutamate (48.6%, P less than 0.001) by lung slices incubated in vitro. 4. Sepsis increased lung blood flow by 27.6% (P less than 0.05). Blood flow and arteriovenous concentration difference measurement across the lung of septic rats showed an increase in the net exchange rates of glutamine (142.5%, P less than 0.001), alanine (129.4%, P less than 0.001), glutamate (100.9%, P less than 0.001) and ammonia (138.0%, P less than 0.001) as compared with sham-operated control rats. 5. Sepsis produced significant decreases in the lung concentrations of glutamine (36.8%), glutamate (20.8%), 2-oxoglutarate (64.8%) and AMP (18.3%). The lung concentrations of alanine (95.9%), ammonia (67.7%) and pyruvate (89.7%) were increased. 6. The maximal activities of glutamine synthetase (20.4%, P less than 0.05), phosphate-dependent glutaminase (18.9%, P less than 0.05) and alanine aminotransferase (25.5%, P less than 0.05) were increased, but there was no marked change in that of glutamate dehydrogenase, in the lungs of septic rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Role of the Liver in Regulation of Ketone Body Production during Sepsis

During caloric deprivation, the septic host may fail to develop ketonemia as an adaptation to starvation. Because the plasma ketone body concentration is a function of the ratio of hepatic production and peripheral usage, a pneumococcal sepsis model was used in rats to measure the complex metabolic events that could account for this failure, including the effects of infection on lipolysis and esterification in adipose tissue, fatty acid transport in plasma and the rates of hepatic ketogenesis and whole body oxidation of ketones. Some of the studies were repeated with tularemia as the model infection. From these studies, it was concluded that during pneumococcal sepsis, the failure of rats to become ketonemic during caloric deprivation was the result of reduced ketogenic capacity of the liver and a possibly decreased hepatic supply of fatty acids. The latter appeared to be a secondary consequence of a severe reduction in circulating plasma albumin, the major transport protein for fatty acids, with no effect on the degree of saturation of the albumin with free fatty acids. Also, the infection had no significant effect on the rate of lipolysis or release of fatty acids from adipose tissue. Ketone body usage (oxidation) was either unaffected or reduced during pneumococcal sepsis in rats. Thus, a reduced rate of ketone production in the infected host was primarily responsible for the failure to develop starvation ketonemia under these conditions. The liver of the infected rat host appears to shuttle the fatty acids away from beta-oxidation and ketogenesis and toward triglyceride production, with resulting hepatocellular fatty metamorphosis.     

Increased rates of hepatic cholesterogenesis and fatty acid synthesis in septic rats in vivo: evidence for the possible involvement of insulin

1. Sepsis induced by caecal ligation and puncture increased the rates of hepatic cholesterogenesis and fatty acid synthesis in vivo compared with sham-operated rats. These changes were accompanied by higher concentrations of lactate and pyruvate in blood and liver and an increase in plasma insulin. 2. The total activity of hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase (EC 1.1.1.88) in liver was increased by sepsis, but there was no significant change in the expressed activity. Short-term insulin deficiency (induced by mannoheptulose or streptozotocin) decreased the rates of cholesterogenesis and fatty acid synthesis in livers of septic rats but did not alter the expressed/total activity of HMG-CoA reductase. 3. It is concluded that the increased rate of hepatic cholesterogenesis in septic rats is in part a result of the higher plasma insulin, the hormone acting to maintain the total activity of HMG-CoA reductase and to stimulate a step before the formation of HMG-CoA. 4. These changes may contribute to the hypertriacylglycerolaemia associated with sepsis.     

Glucose and glutamine metabolism in the small intestine of septic rats

The intestinal metabolism of glucose and glutamine was studied in rats made septic by cecal ligation and puncture technique. Sepsis resulted in negative nitrogen balance and produced increases in the concentrations of blood pyruvate, lactate, alanine, and glutamine, and decreases in those of 3-hydroxybutyrate and acetoacetate. Both plasma insulin and glucagon concentrations were increased by 2.2- and 3.2-fold in septic rats, respectively. Portal-drained visceral blood flow increased in septic rats, and was accompanied by a decrease in the rates of utilization of glutamine and production of lactate, glutamate, and ammonia compared with those rates in sham-operated animals. Enterocytes isolated from septic rats showed decreased rates of glucose and glutamine utilization compared with cells isolated from corresponding controls. The maximal activities of hexokinase, 6-phosphofructokinase, pyruvate kinase, and glutaminase were decreased in intestinal mucosal scrapings of septic rats. It is concluded that a moderate form of sepsis decreases the rates of glucose and glutamine utilization (both in vivo and in vitro) by the epithelial cells of the small intestine. This may be caused by changes in the maximal activities of key enzymes in the pathways of glucose and glutamine metabolism in these cells as a metabolic adaptation to spare glucose and glutamine for use by other tissues.     

Reference values of blood components related to fuel metabolism in children after an overnight fast

The interrelation between blood components, involved in fuel metabolism, and age, sex and glucose was studied in 72 control children (26 girls and 46 boys, aged between 3 and 15 yr) after an overnight fast (14 h). Glucose, lactate, pyruvate, triglycerides and cholesterol are age-independent. Alanine is positively correlated, whereas beta-hydroxybutyrate, acetoacetate and NEFA's are negatively correlated with age. With respect to blood sugar, acetoacetate, NEFA's and cholesterol are glucose-independent. Lactate, pyruvate, alanine and triglycerides are positively correlated with glucose, and beta-hydroxybutyrate--and total ketone bodies--are negatively correlated with glucose. Except for triglycerides, no differences in the concentrations of the above mentioned blood substrates are seen between boys and girls. These data demonstrate that after an overnight fast lipolysis and ketogenesis already are active in young children, probably related to inadequate gluconeogenesis and improvement of carbohydrate regulation with age.     

丙酮酸乙酯对脓毒症大鼠肠黏膜屏障功能保护作用的研究

目的 观察丙酮酸乙酯(ethyl pyruvate ,EP)干预治疗对脓毒症大鼠生存率和肠黏膜屏障的影响.方法 ①EP对脓毒症大鼠生存率的影响:无特定病原雄性SD大鼠100只随机分为假手术组(A组)、脓毒症组(B组)、EP早期治疗组(C组)及EP延迟治疗组(D组),每组25只,利用盲肠结扎穿孔法(cecal ligation and puncture,CLP)制作大鼠脓毒症模型,各组均于术后6、12、18、24、36、48、60、72 h腹腔内注射给药3 mL,C、D组分别于术后6、12 h开始予EP(40 mg/kg),A、B两组同法予等量林格乳酸钠溶液(ringer lactate solution ,RLS),每隔12 h记录死亡情况,分析比较5 d生存率;②EP对脓毒症大鼠肠黏膜屏障的影响:80只无特定病原雄性SD大鼠随机分为四组,每组20只,分组及给药方法与方法一相同,术后24、48 h各处死10只.测定各时间点血浆D-乳酸、DAO的变化,同时用透射电镜观察术后48 h肠黏膜上皮细胞超微结构的变化.采用Kaplan- Meier生存分析法进行生存分析,多组均数间比较采用单因素方差分析的方法, 多组均数间两两比较采用SNK-q检验,P＜0.05为差异有统计学意义.结果 A、B、C、D四组大鼠5 d生存率分别为100%、24%、68%、56%,与B组相比,C、D组大鼠5 d生存率明显提高(P<0.05),C、D组间差异无统计学意义(P＞0.05);与B组相比,C、D组术后24 h和48 h血浆D-乳酸含量明显下降(P<0.01);与B组相比,C组、D术后24 h和48 h血浆DAO活性明显下降(P<0.01),C、D组术后24、48 h血浆D-乳酸含量、DAO活性差异无统计学意义(P＞0.05);电镜下C、D组肠黏膜上皮细胞损伤较B组明显减轻,细胞间紧密连接较清楚.结论 脓毒症时肠黏膜损伤严重,EP早期与延迟干预治疗能有效保护肠黏膜屏障,提高5 d生存率,具有抗脓毒症作用 .     

Role of basal glucagon levels in the regulation of splanchnic glucose output and ketogenesis in insulin-deficient humans

Summary. The aim of the present study was to investigate the influence of hepatic glycogen depletion and increased lipolysis on the response of splanchnic glucose output and ketogenesis to combined glucagon and insulin deficiency in normal man. Healthy subjects were studied after a 60-h fast and compared with a control group studied after an overnight fast, Net splanchnic exchange of glucose, gluconeogenic precursors, free fatty acids (FFA) and ketone acids were measured in the basal state and during intravenous infusion of somatostatin (9 μg/min) for 90–140 min (overnight fasted subjects) or for 5 h (60-h fasted subjects). During the infusion of somatostatin, euglycemia was maintained by a variable intravenous infusion of glucose. Prior to somatostatin infusion, after an overnight (12–14 h) fast, splanchnic uptake of glucose precursors (alanine, lactate, pyruvate, glycerol) could account for 26% of splanchnic glucose output (SGO) indicating primarily glycogenolysis. Somatostatin infusion resulted in a 50% reduction in both insulin and glucagon concentrations and a transient decline in SGO which returned to baseline values by 86±ll min at which point the glucose infusion was no longer necessary to maintain euglycemia. Arterial concentrations of FFA and β-OH-butyrate and splanchnic β-OH-butyrate production rose 2.5-fold, 6-fold and 7.5-fold, respectively, in response to somatostatin infusion. In the 60-h fasted state, basal SGO (0.29±0.03 mmoymin) was 60% lower than after an overnight fast and basal splanchnic uptake of glucose precursors could account for 85% of SGO, indicating primarily gluconeogenesis. Somatostatin administration suppressed the arterial glucagon and insulin concentrations to values comparable to those observed during the infusion in the overnight fasted state. SGO fell promptly in response to the somatostatin infusion and in contrast to the overnight fasted state, remained inhibited by 50–100% for 5 h. Infusion of glucose was consequently necessary to maintain euglycemia throughout the 5-h infusion of somatostatin. Splanchnic uptake of gluconeogenic precursors was unchanged during somatostatin despite the sustained suppression of SGO. Basal arterial concentration and splanchnic exchange of β-OH-butyrate were respectively 22-fold and 6- to 7-fold elevated and basal FFA concentration was 70% increased as compared to the corresponding values in the overnight fasted state. Somatostatin infusion resulted in a rise in arterial FFA concentration (25–50% in all subjects) while the arterial concentrations and splanchnic release of ketone acids (acetoacetate +β-OH-butyrate) showed a variable response, rising in three subjects and declining in two. Nevertheless, splanchnic ketone acid production in the basal state and during the somatostatin infusion correlated directly with splanchnic inflow of FFA (arterial FFA concentration × hepatic plasma flow). The variable responses in ketogenesis could thus be ascribed to variable reductions in splanchnic blood flow induced by somatostatin and as a consequence, its varying effects on splanchnic inflow of FFA. These data thus demonstrate that combined hypoglucagonemia and hypoinsulinemia induced in humans by somatostatin (a) causes a persistent rather than transient inhibition of splanchnic glucose output when liver glycogen stores have been depleted by 60-h fasting and hepatic glucose production is dependent primarily on gluconeogenesis; and (b) fails to interfere with hepatic ketogenesis so long as FFA delivery to the splanchnic bed is maintained. These findings indicate that in the face of insulin deficiency, basal glucagon levels may not be necessary to maintain hepatic glycogenolysis or ketogenesis but may be essential to maintain gluconeogenesis.     

Carrier-mediated efflux of ketone bodies in isolated rat hepatocytes

The rate of efflux of ketone bodies has been studied in isolated hepatocytes prepared from starved rats and preloaded with D-3-[14C]hydroxybutyrate. Efflux of ketone bodies was temperature-dependent, saturable and inhibited by alpha-cyano-3-hydroxycinnamate and phloretin. The rate of efflux was also reduced by 6 mmol/l lactate and pyruvate added to the external medium. Under conditions of simulated metabolic acidosis in the hepatocyte suspension medium, ketone body efflux rate was reduced. The experimental data suggest that hepatic plasma membrane ketone body transit is carrier-mediated.     

The concentration of blood components related to fuel metabolism during prolonged fasting in children

In order to study the relationship between sex, age and glucose, and the concentrations of various fuel related blood substrates in children during prolonged fasting, we have selected data of fasting procedures in 13 control children aged 3-5 yr, fasted 24 h, and 58 control children aged 6-15 yr, fasted 40 h. Compared to the blood results after overnight fast, glucose is decreased, and lactate, pyruvate, ketones and non-esterified fatty acids (NEFA's) are all clearly increased at the end of fast. The concentrations of alanine and triglycerides remain unchanged. The relation with sex, age and glucose has only been analyzed in the older children group. A sex-dependency is indicated for the ketones. Ketones are negatively related with age. NEFA's pyruvate and alanine are not age-related, whereas glucose, lactate and triglycerides are moderately age-dependent. Ketones are negatively related with glucose, whereas pyruvate, NEFA's and triglycerides are not glucose-related. Lactate and alanine are weakly related to glucose. The data demonstrate diminished glucose homeostasis and increased ketogenesis in younger children compared to older ones during prolonged fasting.     

Evolution of lactate/pyruvate and arterial ketone body ratios in the early course of catecholamine-treated septic shock

OBJECTIVES: To measure arterial lactate/pyruvate (L/P) and arterial ketone body ratios as reflection of cytoplasmic and mitochondrial redox state at different stages of catecholamine-treated septic shock and compare them with normal and pathologic values obtained in patients in shock who have decreased oxygen transport (cardiogenic shock), and to assess the relationship between the time course of lactate, L/P ratio, and mortality in septic shock. DESIGN: Prospective, observational human study. SETTING: A university intensive care unit. PATIENTS: Sixty consecutive adult patients who developed septic shock and lactic acidosis requiring the administration of vasopressors. Twenty patients in the intensive care unit without shock, sepsis, and hypoxia and with normal lactate values and 10 patients with cardiogenic shock were also studied. MEASUREMENTS: Hemodynamic measurements, arterial and mixed venous blood gases, arterial lactate and pyruvate concentrations, and arterial ketone body ratio were measured within 4 hrs after the introduction of catecholamine and 24 hrs later. MAIN RESULTS: Fifteen patients (25%) died within the first 24 hrs of septic shock, and these early fatalities had a higher blood lactate (12.2+/-3 versus 4.6+/-1.3 mmol/L; p<.01) concentration and a higher L/P ratio (37+/-4 versus 20+/-1; p<.01) than those who died later. No difference was found for arterial ketone body ratio (0.41+/-0.1 versus 0.50+/-0.06). Forty-five patients survived >24 hrs including 25 survivors and 20 nonsurvivors. Although there was no difference between survivors and nonsurvivors in initial lactate concentration (4.1+/-0.4 and 4.6+/-0.3, respectively), L/P ratio (19+/-1 and 20+/-1, respectively), and arterial ketone body ratio (0.5+/-0.06 and 0.52+/-0.07, respectively), blood lactate and L/P ratio significantly decreased during the first 24 hrs in the survivors (2.8+/-0.4 and 14+/-1, respectively; p<.05). and were stable in the nonsurvivors (4+/-0.3 and 22+/-1, respectively) Although returning to normal values after 24 hrs in survivors and nonsurvivors, arterial ketone body ratio was higher in survivors (1.72+/-0.17 versus 1.09+/-0.15; p<.05). Lactate and L/P ratio were closely correlated (r2 = .8, p<.0001). In the cardiogenic shock group, lactate concentration was 4+/-1 mmol/L, L/P ratio was 40+/-6, and arterial ketone body ratio was 0.2+/-0.05. The mortality rate was 60%. CONCLUSIONS: The main result of the present study is that hemodynamically unstable patients with sepsis needing catecholamine therapy had a lactic acidosis with an elevated L/P ratio and a decreased arterial ketone body ratio, suggesting a decrease in cytoplasmic and mitochondrial redox state. The duration of lactic acidosis is associated with the development of multiple organ failure and death.     

Effect of ketone bodies on glucose production and utilization in the miniature pig.

The effect of ketone bodies on glucose production (Ra) and utilization (Rd) was investigated in the 24-h starved, conscious unrestrained miniature pig. Infusing Na-DL-beta-OH-butyrate (Na-DL-beta-OHB) and thus shifting the blood pH from 7.40 to 7.56 resulted in a decrease of Ra by 52% and of Rd by 45%, as determined by the isotope dilution technique. Simultaneously, the concentrations of arterial insulin and glucagon were slightly enhanced, whereas the plasma levels of glucose, lactate, pyruvate, alanine, alpha-amino-N, and free fatty acids (FFA) were all reduced. Infusion of Na-bicarbonate, which yielded a similar shift in blood pH, did not mimick these effects. Infusion of equimolar amounts of the ketoacid, yielding a blood pH of 7.35, induced similar metabolic alterations with respect to plasma glucose, Ra, Rd, and insulin; however, plasma alanine and alpha-amino-N increased. Infusing different amounts of Na-DL-beta-OHB resulting in plasma steady state levels of ketones from 0.25 to 1.5 mM had similar effects on arterial insulin and glucose kinetics. No dose dependency was observed. Prevention of the Na-DL-beta-OHB-induced hypoalaninemia by simultaneous infusion of alanine (1 mumol/kg X min) did not prevent hypoglycemia. Infusion of Na-DL-beta-OHB plus insulin (0.4 mU/kg X min) showed no additive effect on the inhibition of Ra. Ketones did not inhibit the insulin-stimulated metabolic clearance rate (MCR) for glucose. Infusion of somatostatin (0.2 micrograms/kg X min) initially decreased plasma glucose, Ra, and Rd, which was followed by an increase in plasma glucose and Ra; however, on infusion of somatostatin plus Na-DL-beta-OHB, hypoglycemia and the reduced Ra were maintained. In the anaesthetized 24-h starved miniature pig, Na-DL-beta-OHB infusion decreased the hepatic exchange for glucose, lactate, and FFA, whereas the exchange for glycerol, alanine, and alpha-amino-N as well as liver perfusion rate were unaffected. Simultaneously, portal glucagon and insulin as well as hepatic insulin extraction rate were elevated. Leg exchange for glucose, lactate, glycerol, alanine, alpha-amino-N, and FFA were decreased, while ketone body utilization increased. Repeated infusion of Na-DL-beta-OHB at the fourth, fifth, and sixth day of starvation in the conscious, unrestrained mini-pig resulted in a significant drop in urinary nitrogen (N)-excretion. However, this effect was mimicked by infusing equimolar amounts of Na-bicarbonate. In contrast, when only the ketoacid was given, urinary N-excretion accelerated. To summarize: (a) Ketone bodies decrease endogenous glucose production via an insulin-dependent mechanism; in addition, ketones probably exert a direct inhibitory action on gluconeogenesis. The ketone body-induced hypoalaninemia does not contribute to this effect. (b) The counterregulatory response to hypoglycemia is reduced by ketones. (c) As a consequence of the decrease in R(a), glucose utilization declines during ketone infusion. (d)The insulin-stimulated MCR for glucose is not affected by ketones. (e) Ketones in their physiological moiety do not show a protein-sparing effect.     

Hepatic and renal metabolism before and after portasystemic shunts in patients with cirrhosis.

Hepatic cirrhosis with portal hypertension and gastroesophageal hemorrhage is a disease complex that continues to be treated by surgical portasystemic shunts. Whether or not a reduction or diversion of portal blood flow to the liver adversely affects the ability of the liver to maintain fuel homeostasis via gluconeogenesis, glycogenolysis, and ketogenesis is unknown. 11 patients with biopsy-proven severe hepatic cirrhosis were studied before and after distal splenorenal or mesocaval shunts. Hepatic, portal, and renal blood flow rates and glucose, lactate, pyruvate, glycerol, amino acids, ketone bodies, free fatty acids, and triglyceride arteriovenous concentration differences were determined to calculate net precursor-product exchange rates across the liver, gut, and kidney. The study showed that hepatic contribution of glucose and ketone bodies and the caloric equivalents of these fuels delivered to the blood was not adversely affected by either a distal splenorenal or mesocaval shunt. In addition to these general observations, isolated findings emerged. Mesocaval shunts reversed portal venous blood and functionally converted this venous avenue into hepatic venous blood. The ability of the kidney to make a substantial net contribution of ketone bodies to the blood was also observed.