Biomedical subjects

J E Roselino

Publications and source records attributed to J E Roselino.

16 recordsLinked to original sources

PubMed2000

Gluconeogenesis and P-enolpyruvate carboxykinase in liver and kidney of long-term fasted quails.

The activity of cytoplasmic and mitochondrial phosphoenolpyruvate carboxykinase (PEPCK) in kidney and liver, and in vivo gluconeogenic activity, were determined during different phases of prolonged fasting in quails. The fasting-induced changes in the activity of kidney cytoplasmic PEPCK were positively correlated with the changes in gluconeogenesis. Both activities increased at the initial phase (I) of fasting to levels 65% to 100% higher than fed values, and decreased during the protein-sparing period (phase II), although remaining higher than in fed birds. At the catabolic final phase (III) both kidney cytoplasmic PEPCK activity and gluconeogenesis increased markedly, attaining levels 115% to 150% higher than fed values. The activity of liver cytoplasmic PEPCK, present in appreciable amounts in quails, did not change during phases I and II of fasting, but increased to levels 60% higher than fed values at the final phase (III). Plasma glucose levels at phase III did not differ significantly from those at phases I and II. In both kidney and liver the activity of the mitochondrial PEPCK was not significantly affected by fasting. The data suggest that the kidney cytoplasmic PEPCK is the main enzyme responsible for gluconeogenesis adjustments during food deprivation in quails, and that this function is complemented at the final phase by enzyme present in liver cytosol.

Animals↗

PubMed1996

Effect of acute cold exposure on norepinephrine turnover rates in rat white adipose tissue.

The present studies were carried out to assess directly sympathetic activity in white adipose tissue in response to cold exposure. Norepinephrine (NE) content and NE turnover rates were determined in epididymal and retroperitoneal adipose tissue from rats exposed to cold (4 degrees C) and controls kept at ambient temperature. Parallel measurements were made in interscapular brown adipose tissue (IBAT), in which activation of catecholaminergic innervation by cold exposure is well known. Exposure to 4 degrees C for 4 h reduced the endogenous NE content by 50% in IBAT and by 30% in both epididymal and retroperitoneal adipose tissues. Compared to warm controls, average values of fractional rates of turnover and cf turnover rates, estimated with alpha-methyl-tyrosine, increased 5-fold in IBAT and 2.5-3-fold in epididymal and retroperitoneal tissues from rats exposed to cold. The present data provide the first direct evidence that white adipose tissue sympathetic activity is increased during acute cold exposure.

Adaptation, Physiological↗

PubMed1993

Biochemical and morphological changes in the liver after hepatic artery ligation in the presence or absence of extrahepatic cholestasis.

The present study was carried out to investigate the biochemical and morphological changes in the liver after ligation of the hepatic artery (HA) in the presence and in the absence of extrahepatic cholestasis (EHC). The study was conducted on 100 rats divided into four groups of 25 animals each: group 1, sham operation; group 2, hepatic artery ligation (HAL); group 3, bile duct ligation (BDL); and group 4, HAL plus BDL. All animals were sacrificed 7 days after surgery when total bilirubin and fractions, alkaline phosphatase (AP), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured in serum and on the inner hepatocyte mitochondrial membrane (IHMM); the incidence of necrosis and the volume fractions of vessels, bile ducts and hepatocytes in the liver were also determined. HAL reduces the relative volumes of bile ducts, with no changes in levels of bilirubin and fractions, AP, ALT, AST and IHMM, but HAL associated with EHC reduces duct proliferation and the liver becomes more vulnerable to necrosis. In conclusion, the normal liver depends on HA flow and this dependence is more evident in the presence of EHC.

Alanine Transaminase↗

PubMed1992

Lack of control of liver gluconeogenesis in cholestatic rats with reduced portal blood flow.

Previous studies indicated a role for ischemia in the metabolic changes induced by cholestasis. Liver pyruvate kinase is a key enzyme for the concurrent control of glycolysis and gluconeogenesis. In this experiment the control of pyruvate kinase activity was investigated in cholestatic rats. Pyruvate kinase kinetics changed from a sigmoidal type in sham-operated rats to a hyperbolic type in obstructed rats. The change in the enzymatic kinetics paralleled the reduction in the portal blood flow, which reached 50% of the control value 7 days after obstruction. Dibutyryl cyclic AMP (5 mumol/kg body wt) plus theophylline 0.1 mmol/L failed to inactivate the enzyme when injected into the portal veins of rats whose livers were obstructed 7 days before. Both the kinetics changes and the lack of phosphorylation control are compatible with ischemia.

Animals↗

PubMed1992

Hepatic morphology changes after hepatic artery ligation in extrahepatic cholestasis.

The present study was performed to correlate changes in hepatic morphology with hepatic artery ligation (HAL) in the presence of extrahepatic cholestasis (EHC). The study was conducted on 36 male Wistar rats weighing 350 to 400 g, divided at random into four groups of 9 animals each: group I, sham operation (control); group II, HAL; group III, bile duct ligation (BDL); group IV, HAL plus BDL. After seven days, liver fragments were obtained for morphological study. The relative volume of the bile ducts was I > II < III and III > IV (P < 0.05). These data indicate that arterial irrigation is important for the nutrition of the biliary tree. Seventy-six percent of the animals submitted to HAL plus BDL showed hepatic necrosis. In general, the liver probably becomes more dependent on HA flow in the presence of EHC.

Animals↗

PubMed1991

Intramitochondrial calcium and magnesium levels in skeletal muscle submitted to total or partial limb ischemia.

Skeletal muscle temperature and mitochondrial content of Ca2+ and Mg2+ were measured after 3 h of total or partial limb ischemia in male Wistar rats (250-350 g). The decreases in biceps muscle temperature, measured with a needle thermistor (4.4 +/- 0.26 degrees C, mean +/- SEM (17 rats) and 6.3 +/- 0.26 degrees C (31 rats) in partial ischemia (PI, aorta clamp) and total ischemia (TI, hind leg tourniquet), respectively) were consistent with the expected extent of blood flow reduction for the two ischemic conditions. Mitochondrial calcium levels increased after partial ischemia from 2.67 +/- 0.13 (46 rats) to 4.65 +/- 0.38 (12 rats) nmol/mg protein and increased to 7.87 +/- 0.68 (14 rats) after total ischemia (P less than 0.05). In contrast, mitochondrial magnesium decreased after partial ischemia from 10.14 +/- 0.35 to 8.22 +/- 0.28 (13 rats) but increased in the mitochondria of muscle submitted to total ischemia to 12.0 +/- 0.80 (14 rats; P less than 0.05). No changes were observed in the number of binding sites for safranine, which competes for calcium binding sites on the inner mitochondrial membrane (25.46 +/- 0.38 nmol/mg protein for sham (20 rats) and 25 +/- 0.68 (7 rats) for PI and 25 +/- 0.31 (5 rats) for TI). The data suggest that the greater resistance of rat muscle to total than to partial ischemia may be due at least in part to the increased mitochondrial Mg2+ content.

Animals↗

PubMed1991

Integrity of liver inner mitochondrial membrane in rats with extrahepatic cholestasis.

To investigate the effect of extrahepatic cholestasis on integrity of the inner mitochondrial membrane, a study was conducted on two groups of rats: sham-operated control animals (N = 10) and rats subjected to extrahepatic cholestasis (EHC, N = 10) by double ligation of the hepatic duct. The animals were observed for 7 days and then sacrificed. The EHC group presented significantly higher serum levels of alanine aminotransferase, total bilirubins and alkaline phosphatase than the controls (P less than 0.01). Basal mitochondrial respiration (state IV), analyzed separately using either alpha-ketoglutarate or alpha-ketoglutarate + pyruvate as substrates, was similar in the two groups (P greater than 0.01). ADP-activated respiration, state III, diminished significantly in the EHC group. The results show that the decrease in mitochondrial function that has been reported by several investigators to occur in EHC is due to mitochondrial alterations not related to the ability of these organelles to maintain the proton gradient, since the inner mitochondrial membrane continued to be energized throughout the observation period.

Alanine Transaminase↗

PubMed1990

Serum transaminase levels in the acute phase of chronic extrahepatic cholestasis.

Serum alanine aminotransferase (ALT) and serum aspartate aminotransferase (AST) levels are normal or discretely increased in rats with chronic extrahepatic cholestasis (CEHC). During the acute phase (first 72 h after biliary obstruction), however, serum transaminase values are quite elevated due to a mechanism not yet fully elucidated. Thus, this is a good experimental model, not involving hepatocellular necrosis, for the study of serum ALT and AST levels during the acute phase of CEHC. Male Wistar rats (250-350 g) were divided into two groups: group A (N = 60) was submitted to sham operation for bile duct ligation (BDL), and group B (N = 60) was submitted to BDL. Thirty and 120 min after BDL there was a 1.5-fold increase in both serum ALT and AST levels compared to sham-operated rats (P less than 0.05). Serum ALT levels were higher than AST levels as early as 30 min after BDL and the highest serum values for both transaminases were observed at 360 min which was also the last value measured. Serum AST levels increased 120 min after BDL, with no further significant increases thereafter.

Alanine Transaminase↗

PubMed1990

Effect of hepatic artery ligation in rats with chronic extrahepatic cholestasis.

Because of the liver's dependence on arterial blood to exert its metabolic functions in cirrhosis of the liver, with or without thrombosis of the portal vein, the interruption of hepatic arterial flow for the palliative treatment of malignant tumors of the liver is counterindicated. However, the effects of arterial devascularization on the cholestatic liver are not fully understood. The objective of the present study was to investigate hepatic alterations due to hepatic artery ligation in rats with chronic extrahepatic cholestasis. Serum alkaline phosphatase, bilirubin and alanine aminotransferase were measured in rats 3 h after sham operation (group A, N = 29) or ligation of the hepatic artery (group B, N = 29). Alanine aminotransferase activity was significantly higher (P less than 0.05) in group B, demonstrating acute hepatocellular damage in animals with chronic extrahepatic cholestasis.

Alanine Transaminase↗

PubMed1989

Rapid activation of gluconeogenesis after intracerebroventricular carbachol.

Intracerebroventricular administration of carbachol (27 nmol in 5 microliters 0.15 M NaCl) produced marked hyperglycemia in 24-h fasted rats, despite the negligible amounts of preformed liver glycosyl residues. To investigate the possibility of a stimulation of gluconeogenesis, conscious unrestrained rats were continuously infused with [14C]bicarbonate (0.51 microliters, 0.18 muCi/min) and label incorporation into circulating glucose determined before and after intraventricular injection. The rate of 14C incorporation into blood glucose of fed rats was not affected by intraventricular injection of 0.15 M NaCl but increased significantly after carbachol administration. In both fed and 24-h fasted rats the hyperglycemia induced by intraventricular carbachol was accompanied by marked increases in plasma lactate. Previous adrenodemedullation prevented both the hyperglycemia and the hyperlactemia. Liver pyruvate kinase activity was reduced in carbachol-treated rats, when the enzyme was assayed with suboptimal concentrations of phosphoenolpyruvate and in the absence of fructose 1,6-biphosphate. Phosphoenolpyruvate carboxykinase activity was not affected. The data suggest that central chemical stimulation with cholinergic agents induces a rapid activation of liver gluconeogenesis, which probably results from an increased sympathetic outflow for epinephrine secretion by the adrenal medulla.

Animals↗

PubMed1989

Effect of fasting on glucose turnover in a carnivorous fish (Hoplias sp).

Intravenous glucose tolerance tests and measurements with [6-3H]glucose of rate of glucose replacement, transit time, and body glucose mass were performed in fed and fasted Hoplias malabaricus. Both glycemia levels and the rate of decline of blood glucose following intravenous administration of 500 mg/kg glucose were significantly lower in 60-day-fasted than in fed fish. Changes in plasma free fatty acids were opposite to those in blood glucose. The rate of glucose replacement, calculated graphically from mean +/- 3 SE plots of glucose specific radioactivity, was 0.71 (0.66-0.77) mg.kg-1.min-1 in fed H. malabaricus and decreased to 0.51 (0.46-0.56) mg.kg-1.min-1 after 60 days without food, with a concomitant reduction of body glucose mass (mmin, 138 vs. 83 mg/kg). In fish starved for 10 mo the rate of glucose replacement and body glucose mass were further reduced to 0.35 (0.29-0.42) mg.kg-1.min-1 and 57 mg/kg (mmin), respectively. It is concluded that a progressive decline in the rate of glucose utilization contributes to the adaptation of fish to prolonged fasting.

Animals↗

PubMed1989

Effect of chlorpromazine and biliary drainage on portal blood flow and mitochondrial function during extrahepatic cholestasis.

The present study examines the effect of chlorpromazine and biliary drainage in cholestatic rats. The time course of portal blood flow was studied 24, 48, and 72 h and seven days after bile duct ligation. Portal blood flow decreased after 72 h. Chlorpromazine reduced biliary hydrostatic pressure in sham-operated control rats, but 24-h obstruction was sufficient to prevent this effect in cholestatic rats. The drug ameliorated the mitochondrial and cell membrane function of cholestatic rats before and after drainage. The data present further support for the role of ischemia in cholestasis.

Alanine Transaminase↗

PubMed1989

High chlorpromazine doses and liver function.

The aim of the present study was to evaluate the in vivo effect of high chlorpromazine (CPZ) doses on hepatocellular function. Thirty male Wistar rats weighing 200 to 250 g were divided into two groups: control (C, N = 17), injected ip with saline, and CPZ (N = 13), injected ip with high chlorpromazine doses (initial dose of 30 mg/kg body weight followed by daily doses of 10 mg/kg for 7 days). No significant differences in serum levels of alanine-aminotransferase, alkaline phosphatase and bilirubin or in mitochondrial function (activated and basal respiration and mitochondrial respiration control (activated/basal ratio) were detected between the two groups.

Alanine Transaminase↗

PubMed1988

Effects of starvation, refeeding, and insulin on energy-linked metabolic processes in catfish (Rhamdia hilarii) adapted to a carbohydrate-rich diet.

The effects of starvation and of a short period of refeeding on energy-linked metabolic processes, as well as the effects of insulin administration, were investigated in an omnivorous fish (catfish, Rhamdia hilarii) previously adapted to a carbohydrate-rich diet. Following food deprivation blood sugar levels declined progressively to about 50% of fed values after 30 days. During the same period plasma free fatty acid (FFA) concentration increased twofold. Starvation resulted in reduced concentrations of lipid and glycogen in the liver and of glycogen, lipid, and protein in white muscle. However, taking into account the initial and final concentrations of tissue constituents, the liver weight, and the large fractions of body weight represented by muscle, it could be estimated that most of the energy utilized during starvation derived from the catabolism of muscle lipid and protein. Refeeding starved fishes for 48 hr induced several-fold increases in the rates of in vivo and in vitro incorporation of [14C]glucose into liver and muscle lipid and of [14C]glycine into liver and muscle protein. Incorporation of [14C]glucose into liver glycogen was also increased. However; refeeding did not affect the incorporation of labeled glucose into muscle glycogen, neither in vivo nor in vitro. Administration of pharmacological doses of insulin to normally fed catfishes resulted in marked increases in the in vivo incorporation of 14C from glucose into lipid and protein in both liver and muscle. In contrast, labeled glucose incorporation into muscle glycogen was not affected by insulin and label incorporation into liver glycogen was actually lower than that in noninjected controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗

PubMed1988

Portal flow and mitochondrial function during extrahepatic cholestasis.

This study was designed to determine portal blood flow and mitochondrial and hepatic function during extrahepatic obstruction. Twenty-two male Wistar rats which had undergone bile duct ligation were compared 7 days later to 20 sham-operated controls. Portal flow and mitochondrial respiratory control ratio were reduced by 50% and 35%, respectively (P less than 0.01), and serum alanine-aminotransferase levels increased significantly (P less than 0.01) in the extrahepatic cholestatic group. These results suggest that cholestasis may cause an imbalance between the energy supply and the high demand of the liver leading to a state of partial ischemia.

Alanine Transaminase↗

PubMed1979

Adenylyl cyclase deficient cr-1 (Crisp) mutant of Neurospora crassa: cyclic AMP-dependent nutritional deficiencies.

The inability to synthesize cyclic AMP drastically affects the nutritional metabolism of Neurospora crassa. The adenylyl cyclase-less mutant cr-1 (crisp) did not utilize several carbon sources, including glycerol, mannitol, arabinose, and casaminoacids. However, in glucose or acetate it grew as well as the wild type. The following evidence suggested that these nutritional deficiencies were a direct result of the cr-1 mutation: (i), in crosses to wild type they segregated together with the crisp morphological marker; (ii), cyclic AMP added to the cr-1 mutant growth medium overcame the nutritional deficiencies; (iii), the cyclic AMP effect was specific for the crisp mutant, for it was not observed with the wild type, nor with a spontaneous glycerol-utilizing cr-1 strain.

Acetates↗