scholarly journals Lactate Accumulation during Moderate Hypoxic Hypoxia in Neocortical Rat Brain

1996 ◽  
Vol 16 (6) ◽  
pp. 1345-1352 ◽  
Author(s):  
Jean-François Payen ◽  
Emmanuelle LeBars ◽  
Bernard Wuyam ◽  
Bernard Tropini ◽  
Jean-Louis Pépin ◽  
...  
Keyword(s):  
Control Period ◽  
Relaxation Times ◽  
Significant Rise ◽  
Hypoxic Hypoxia ◽  
Metabolic Effects ◽  
Marked Rise ◽  
Arterial Lactate ◽  
Apparent Decrease ◽  
Lactate Infusion ◽  
Lactate Peak

Neocortical metabolism was studied during moderate hypoxic hypoxia, reoxygenation, and postmortem periods in anesthetized normocapnic rats using 1H nuclear magnetic resonance (NMR) spectroscopic imaging. Rats were prepared with unilateral common carotid occlusion to determine the ipsilateral metabolic effects of inadequate cerebral blood flow (CBF) response to hypoxia. No difference in brain metabolism between the two hemispheres was found during the control period. Hypoxic hypoxia (Pao2 = 54.1 ± 5.8 mm Hg) resulted in a significant rise in neocortical lactate peak in both hemispheres, with an additional marked rise in the clamped side compared to the unclamped side (53 ± 27 vs. 22 ± 13% of postmortem value, p < 0.001). These lactate changes were not reversible within 30 min of reoxygenation in the clamped hemisphere. No changes in neocortical lactate peak were observed while elevating arterial lactate via intravenous lactate infusion without hypoxia. In addition, hypoxic hypoxia resulted in an apparent decrease in neocortical water and N-acetyl aspartate (NAA) signals, which were related to a shortening in T2 relaxation times. It is concluded that neocortical lactate is an early metabolic indicator during moderate hypoxic hypoxia in normocapnic conditions.

The Role of the Aortic Body Chemoreceptors in the Cardiac and Respiratory Responses to Acute Hypoxia in the Anesthetized Dog

1973 ◽  
Vol 51 (4) ◽  
pp. 249-259 ◽  
Author(s):  
G. P. Biro ◽  
J. D. Hatcher ◽  
D. B. Jennings
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Acute Hypoxia ◽  
Control Period ◽  
Indirect Evidence ◽  
Minute Volume ◽  
Significant Rise ◽  
Cardiac Response ◽  
Cardiac Responses ◽  
Respiratory Parameters

The participation of the aortic chemoreceptors in the reflex cardiac responses to acute hypoxia is suggested only by the indirect evidence of pharmacological stimulation of these receptors. In order to assess their role more directly, the response to a 15 min period of hypoxia was determined after surgical denervation of the aortic chemoreceptors (A.D.), and compared with the response of sham-operated (S.O.) dogs, anesthetized with morphine–pentobarbital. In the control period, while breathing room air, the cardiovascular and respiratory parameters measured in the A.D. animals were not different from those of the S.O. dogs. Hypoxia (partial pressure of oxygen approximately 30 mm Hg) in the S.O. dogs was associated with a statistically significant rise in the heart rate (+71 ± 7 min−1, mean ± S.E.M.) and of the cardiac output (+25 ± 10 ml kg−1 min−1). In the A.D. animals, the significantly smaller increment in heart rate (+29 ± 6 min−1) was associated with a fall of the cardiac output (−16 ± 12 ml kg−1 min−1). The hypoxia-induced changes in heart rate and cardiac output in the S.O. animals were different (p < 0.05) from those in the A.D. group. The minute volume of ventilation was significantly augmented in both groups, and to a comparable extent. These findings indicate that the aortic chemoreceptors play a significant role in the cardiac response to hypoxia, but they do not affect, to a significant extent, the respiratory response.

scholarly journals Effect of Acute Sprint Exercise on Myokines and Food Intake Hormones in Young Healthy Men

2020 ◽  
Vol 21 (22) ◽  
pp. 8848
Author(s):  
Jan Bilski ◽  
Agnieszka Irena Mazur-Bialy ◽  
Marcin Surmiak ◽  
Magdalena Hubalewska-Mazgaj ◽  
Janusz Pokorski ◽  
...  
Keyword(s):  
Food Intake ◽  
Plasma Levels ◽  
Acute Exercise ◽  
Control Period ◽  
Human Growth ◽  
Significant Rise ◽  
Short Term ◽  
Postprandial Period ◽  
Young Males ◽  
Meal Intake

Physical exercise is known to influence hormonal mediators of appetite, but the effect of short-term maximal intensity exercise on plasma levels of appetite hormones and cytokines has been little studied. We investigated the effect of a 30 s Wingate Test, followed by a postprandial period, on appetite sensations, food intake, and appetite hormones. Twenty-six physically active young males rated their subjective feelings of hunger, prospective food consumption, and fatigue on visual analogue scales at baseline, after exercise was completed, and during the postprandial period. Blood samples were obtained for the measurement of nesfatin-1, ghrelin, leptin, insulin, pancreatic polypeptide (PP), human growth factor (hGH) and cytokine interleukin-6 (IL-6), irisin and plasma lactate concentrations, at 30 min before exercise, immediately (210 s) after exercise, and 30 min following a meal and at corresponding times in control sedentary males without ad libitum meal intake, respectively. Appetite perceptions and food intake were decreased in response to exercise. Plasma levels of irisin, IL-6, lactate, nesfatin-1 and ghrelin was increased after exercise and then it was returned to postprandial/control period in both groups. A significant rise in plasma insulin, hGH and PP levels after exercise was observed while meal intake potentiated this response. In conclusion, an acute short-term fatiguing exercise can transiently suppress hunger sensations and food intake in humans. We postulate that this physiological response involves exercise-induced alterations in plasma hormones and the release of myokines such as irisin and IL-6, and supports the notion of existence of the skeletal muscle–brain–gut axis. Nevertheless, the detailed relationship between acute exercise releasing myokines, appetite sensations and impairment of this axis leading to several diseases should be further examined.

Failure of somatostatin to modify effect of glucagon on carbohydrate metabolism in the dog

1983 ◽  
Vol 244 (6) ◽  
pp. E596-E602 ◽  
Author(s):  
A. D. Cherrington ◽  
W. W. Lacy ◽  
P. E. Williams ◽  
K. E. Steiner
Keyword(s):  
Carbohydrate Metabolism ◽  
Metabolic Regulation ◽  
Plasma Insulin ◽  
Endocrine Pancreas ◽  
Control Period ◽  
Glucose Production ◽  
Metabolic Effects ◽  
Plasma Glucagon ◽  
Modify Effect

Somatostatin is widely used to inhibit insulin and glucagon release by the pancreas in studies of metabolic regulation in vivo. To determine whether the peptide can directly modify the metabolic effects of an increment in glucagon in overnight-fasted conscious dogs, glucagon was increased in the presence (+S) or absence (-S) of somatostatin. Either somatostatin (+S; 0.8 microgram . kg-1 . min-1) or a two-stage pancreatectomy (-S) was used to inhibit the endocrine pancreas, and at the same time replacement infusions of insulin (285-300 microU . kg-1 .min-1) and glucagon (0.65 ng . kg-1 . min-1) were given. After a 40-min control period the plasma glucagon level was raised fourfold in the presence of fixed basal insulin. Plasma insulin in both groups were similar [11 +/- 2 (+S) and 9 +/- 1 (-S) microU/ml]. Glucagon rose from 64 +/- 11 to 225 +/- 19 and 92 +/- 11 to 219 +/- 20 pg/ml in the +S and -S groups, respectively. Tracer-determined ([3-3H]glucose) glucose production rose by 5.28 +/- 1.02 (+S) and 4.25 +/- 1.12 (-S) mg . kg-1 . min-1 at 15 min and fell similarly over 3 h in both groups. Plasma glucose rose similarly in both groups peaking at 195 +/- 15 (+S) and 174 +/- 8 (-S) mg/dl. Plasma alanine fell similarly over 3 h [133 +/- 35 (+S) and 138 +/- 42 (-S) mumol/liter]. Conversion of [14C]alanine and [14C]-lactate to [14C]glucose rose progressively over 3 h in both groups, eventually being elevated by 210 +/- 58 (+S) and 148 +/- 48% (-S). We conclude that in the dog somatostatin at the dose used does not alter the effect of an increment in glucagon on carbohydrate metabolism.

Effective Use of Amino Acid Dialysate over four Weeks in CAPD Patients

1983 ◽  
Vol 3 (2) ◽  
pp. 66-72 ◽  
Author(s):  
Arie Oren ◽  
George Wu ◽  
G. Harvey Anderson ◽  
Errol Marliss ◽  
Ramesh Khanna ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Acid Solution ◽  
Serum Albumin ◽  
Hdl Cholesterol ◽  
Significant Rise ◽  
Protein Malnutrition ◽  
Metabolic Effects ◽  
Amino Acid Solution ◽  
Total Body

We studied the effectiveness, tolerance to, and beneficial metabolic effects of amino acid dialysate over an intermediate period in six CAPD patients. Two liters of 1% amino acid solution (Amino-Dianeal) were alternated with dialysate containing glucose. After four weeks there were significant increases in BUN (from 64 to 102 mg%), total body nitrogen (from 1333 to 1380 g), serum transferrin (from 175 to 222 mg%) and anion gap (from 15.1 to 17.3). Initially, there was a significant rise in HDL cholesterol, however, this was not sustained. No significant change was detected in total-body potassium, fasting serum albumin, triglyceride, insulin, glucagon, electrolytes, anthropometric measurements and daily ingestion of calories and proteins. During the study individual fasting, plasma amino acid levels showed significant increments in respect to histidine, tryptophan and glycine but alanine decreased. Several essential amino acids continued to show values below normal. Two hours after consumption of breakfast and concurrent infusion of the amino acid solution, the plasma levels of the amino acids in the dialysate peaked at emia, which develops in almost onehalf of the CAPD patients (7), and the significant weight gain observed in some of them. Furthermore, the daily losses of albumin and amino acids in the dialysate may induce protein malnutrition, especially if these losses are not replaced by an adequate daily protein intake. The presence of protein malnutrition in CAPD patients is indicated by the low serum albumin and total protein, and by the decrease in total body nitrogen over one year of CAPD (8).

Electrolyte, water, and urea content in dog kidneys in different states of diuresis

1964 ◽  
Vol 206 (4) ◽  
pp. 725-730 ◽  
Author(s):  
Alfonso Ruiz-Guiñazú ◽  
Elvira E. Arrizurieta ◽  
Laura Yelinek
Keyword(s):  
Water Content ◽  
Significant Rise ◽  
The State ◽  
Water Diuresis ◽  
Outer Medulla ◽  
Marked Rise ◽  
Kidney Slices ◽  
Urea Content ◽  
The Creation

Thin kidney slices of dogs in hydropenia and water diuresis were analyzed for water, electrolytes, and urea content. The sodium and chloride contents are uniform throughout the cortex, but rise very markedly in the outer medulla, more during hydropenia than during water diuresis. Throughout the inner medulla a uniform content was observed, about 30% higher during hydropenia. The water content was uniform at all levels in the cortex, and increasing in the outer medulla, regardless of the state of hydration. In the inner medulla the content rose toward the papilla during water diuresis and decreased in the same direction during hydropenia. The urea content showed a very marked rise throughout the medulla during hydropenia and no significant rise during water diuresis. It was concluded that the great bulk of medullary sodium is pumped in the thick portion of the ascending limb of Henle and that the changes in water and urea contents bear the main responsibility in the creation of osmotic gradients within the inner medulla during hydropenia.

Changes in plasma Cortisol and progesterone after administration of enkephalins to newborn lambs

1982 ◽  
Vol 60 (9) ◽  
pp. 1166-1170 ◽  
Author(s):  
George D. Carson ◽  
John R. G. Challis
Keyword(s):  
Plasma Cortisol ◽  
Control Period ◽  
Significant Rise ◽  
Pituitary Hormone ◽  
Hormone Release ◽  
Plasma Progesterone ◽  
Methionine Enkephalin ◽  
Leucine Enkephalin ◽  
Transient Rise ◽  
The Mean

Methionine-enkephalin and leucine-enkephalin were injected into the brachiocephalic artery of lambs at 8–18 days of age. There was a significant increase in the concentration of Cortisol in plasma 15 – 30 min after leucine-enkephalin (10-, 100-, and 500-μg bolus). After the 100-μg bolus, there was a biphasic response and a second significant rise in Cortisol was seen at 90 min. Plasma progesterone was elevated significantly at 15–30 min and at 90 min after the 100- and 500-μg injections of leucine-enkephalin. Methionine-enkephalin (100 μg) produced a transient rise in plasma Cortisol at 15 – 30 min, although the mean concentrations were not statistically different from the control period. We conclude that in newborn lambs, enkephalins may influence adrenal function. It is likely that such an action is secondary to effects on brain or pituitary hormone release.

The Effect of Hypoxia on Succinate Metabolism in Man and the Isolated Perfused Dog Liver

1972 ◽  
Vol 42 (1) ◽  
pp. 35-45 ◽  
Author(s):  
R. A. Iles ◽  
D. Barnett ◽  
L. Strunin ◽  
J. M. Strunin ◽  
B. R. Simpson ◽  
...  
Keyword(s):  
Hypoxic Hypoxia ◽  
Permeability Barrier ◽  
Perfused Liver ◽  
Tissue Concentrations ◽  
Marked Rise ◽  
Oxidative Pathway ◽  
Dog Liver

1. A marked rise in blood succinate was shown to occur in severely hypoxic patients. 2. A similar effect could be produced in the perfusate of the isolated perfused canine liver subjected to hypoxic hypoxia; in addition, tissue concentrations of succinate in the perfused liver progressively rose during hypoxia. 3. The elevation of succinate concentrations during hypoxia is partly due to reversal of the oxidative pathway from succinate to oxaloacetate. 4. A permeability barrier to succinate and fumarate exists between their locations within the cell and the circulation. 5. The permeability barrier to succinate but not to fumarate is broken down during hypoxia.

scholarly journals Blood Lactate is an Important Energy Source for the Human Brain

2009 ◽  
Vol 29 (6) ◽  
pp. 1121-1129 ◽  
Author(s):  
Gerrit van Hall ◽  
Morten Stømstad ◽  
Peter Rasmussen ◽  
Øle Jans ◽  
Morten Zaar ◽  
...  
Keyword(s):  
Energy Source ◽  
Human Brain ◽  
Arterial Lactate ◽  
Oxidation Rates ◽  
Lactate Uptake ◽  
Lactate Utilization ◽  
Lactate Infusion ◽  
The Brain ◽  
Brain Energy

Lactate is a potential energy source for the brain. The aim of this study was to establish whether systemic lactate is a brain energy source. We measured in vivo cerebral lactate kinetics and oxidation rates in 6 healthy individuals at rest with and without 90 mins of intravenous lactate infusion (36 μmol per kg bw per min), and during 30mins of cycling exercise at 75% of maximal oxygen uptake while the lactate infusion continued to establish arterial lactate concentrations of 0.89 ± 0.08, 3.9 ± 0.3, and 6.9 ± 1.3 mmol/L, respectively. At rest, cerebral lactate utilization changed from a net lactate release of 0.06 ± 0.01 to an uptake of 0.16 ± 0.07 mmol/min during lactate infusion, with a concomitant decrease in the net glucose uptake. During exercise, the net cerebral lactate uptake was further increased to 0.28 ± 0.16 mmol/min. Most 13C-label from cerebral [1-13C]lactate uptake was released as 13CO2 with 100% ± 24%, 86% ± 15%, and 87% ± 30% at rest with and without lactate infusion and during exercise, respectively. The contribution of systemic lactate to cerebral energy expenditure was 8% ± 2%, 19% ± 4%, and 27% ± 4% for the respective conditions. In conclusion, systemic lactate is taken up and oxidized by the human brain and is an important substrate for the brain both under basal and hyperlactatemic conditions.

scholarly journals Modeling Cerebral Arteriovenous Lactate Kinetics after Intravenous Lactate Infusion in the Rat

2004 ◽  
Vol 24 (10) ◽  
pp. 1071-1080 ◽  
Author(s):  
Gea Leegsma-Vogt ◽  
Siebren van der Werf ◽  
Kor Venema ◽  
Jakob Korf
Keyword(s):  
Mathematical Model ◽  
Flow Injection Analysis ◽  
Brain Volume ◽  
Venous Blood ◽  
High Temporal Resolution ◽  
Arterial Lactate ◽  
Lactate Kinetics ◽  
Subsequent Application ◽  
Lactate Infusion ◽  
The Brain

Venous-arterial lactate differences across the brain during lactate infusion in rats were studied, and the fate of lactate was described with a mathematical model that includes both cerebral and extracerebral kinetics. Ultrafiltration was used to sample continuously and simultaneously arterial and venous blood. Subsequent application of flow injection analysis and biosensors allowed the measurement of glucose and lactate concentrations every minute. Because of the high temporal resolution, arteriovenous lactate kinetics could be modeled in individual experiments. The existence of both a cerebral lactate sink and a lactate exchangeable compartment, representing approximately 24% of brain volume, was thus modeled.

Effect of lactate infusion on myocardial FFA metabolism in diabetic dogs

1975 ◽  
Vol 229 (4) ◽  
pp. 973-976 ◽  
Author(s):  
JJ Spitzer
Keyword(s):  
Ketone Bodies ◽  
Lactate Concentration ◽  
Co2 Production ◽  
Constant Infusion ◽  
Myocardial Uptake ◽  
Arterial Lactate ◽  
Myocardial Substrate ◽  
Diabetic Dogs ◽  
Beta Hydroxybutyrate ◽  
Lactate Infusion

The effect of elevated arterial lactate concentration on myocardial free fatty acid (FAA), acetoacetate (AcAc), and beta-hydroxybutyrate (beta-OHB) uptake was studied in alloxan-diabetic dogs under control conditions and following the constant infusion of Na-L-(+)-lactate. Only minor changes in hemodynamic parameters were observed. During lactate infusion, arterial lactate increased and FFA, AcAc, and beta-OHB decreased. The extraction ratio and myocardial uptake of both AcAc and beta-OHB diminished. No significant change of myocardial FFA oxidation was noted. While myocardial lactate uptake was very small under control conditions, it increased considerably during the infusion of lactate. The fraction of myocardial CO2 production derived from FFA oxidation was unchanged during lactate infusion, while the fraction derived from ketone bodies decreased and that derived from lactate increased. Thus, during hyperlactacidemia a larger fraction of myocardial substrate was derived from lactate and a smaller fraction from ketone bodies than were derived under control conditions.

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