Metabolic Activity In Response Research Articles

Effect of strenuous exercise stress on chemiluminescence response of equine alveolar macrophages

Bronchoalveolar lavage samples were collected using a fibreoptic endoscope from horses at specified times before and after single bouts of exercise. Lucigenin-dependent phagocytic chemiluminescence was used to assess the effect of exercise on the alveolar macrophage metabolic activity in response to stimulation by opsonised zymosan. A profound suppressive effect on the chemiluminescence production was present throughout the first three days after exercise. However, the cellular composition of lavage fluids was not altered by the exercise. It is suggested that strenuous exercise may jeopardize the antimicrobial function of alveolar macrophages which may lead to an increase in susceptibility to infection.

Visceral Organ Size and Hepatocyte Metabolic Activity in Fed and Fasted Rats

Changes in visceral organ mass and hepatocyte metabolic activity in response to nutrient deprivation were studied in male Sprague-Dawley rats. Forty-two rats (320 g) were given ad libitum access to feed or fasted for 72 h after which time visceral organ mass and metabolic activity were measured. Liver metabolic activity was measured in vitro by [14C]valine incorporation into acid-precipitable protein and oxygen consumption in isolated hepatocytes. Fasted rats had lower weights of liver and intestines and similar kidney and stomach weights relative to body weight than fed rats. Compared with fed controls, fasted rats had lower RNA and higher DNA concentrations in liver and intestines with decreased RNA and protein mass in all visceral organs. Nutrient deprivation generally resulted in reduced ratios of RNA/DNA and protein/DNA in visceral tissues. Nutrient deprivation had no effect on in vitro oxygen consumption or [14C]valine incorporation expressed per g tissue. However, in vitro oxygen consumption and valine incorporation expressed per unit DNA and estimated total liver oxygen consumption were reduced in fasted rats. These data suggest that nutrient deprivation reduced visceral organ mass of RNA and protein primarily through an apparent reduction in cell size. Nutrient deprivation resulted in decreased liver oxygen consumption because of decreased organ size rather than by tissue metabolic activity.

Single vibrissal cortical column in SI cortex of rat and its alterations in neonatal and adult vibrissa-deafferented animals: a quantitative 2DG study.

1. A quantitative 2-[14C]deoxy-D-glucose (2DG) autoradiographic study was undertaken to determine the functional (metabolic) organization of an individual column in the first somatosensory cortex (SI) of the awake restrained rat. Manual or mechanically controlled brush stroking of a single vibrissa (typically C3) was used in order to evoke neural activity and increase glucose utilization in a single cortical barrel in lamina IV and in adjacent supra- and infragranular layers in register with the single cortical barrel labeling in lamina IV. 2. The single activated vibrissal column was found to extend from layer I to the superficial half of layer VI of the contralateral SI cortex and was fusiform in shape, being of largest diameter (650-micron) in layer IV and smallest diameter (200 micron) in layer VI. 3. This single metabolic column was not uniform in its density of labeling. The greatest local cerebral metabolic rate of glucose (LCMRG) was found in layer IV (170 mumol.100 g-1.min-1), layers II-III, and V had, on the average, similar LCMRG values (115 mumol.100 g-1.min-1), which decreased with distance from layer IV. 4. The functional (metabolic) columnar activity center situated in layer IV corresponded in size to the appropriate anatomical barrel as determined from thionin-stained sections. Increased metabolic activity was not strictly confined to the candle-pin-shaped column but extended tangentially as radiating fingerlike projections toward the neighboring barrels. 5. In cortical layers other than IV, the metabolic column was less prominently labeled, and the metabolic activity also branched in the tangential plane. The labeling pattern profile in upper layers was characterized by numerous lateral spreading fingerlike projections of increased glucose metabolism. 6. Neonatal follicle lesions sparing only C3 vibrissa caused a great increase (125%) in cortical territory driven by the spared whisker with a concomitant loss of columnar shape and decrease in intensity of metabolic activity in response to its stimulation. 7. Similar lesions in adult rats produced a significant increase (40%) in dimensions of the spared C3 cortical column, which was, however, smaller than that produced after neonatal lesions. The metabolic activation of layer Vb in the spared C3 column was increased (17%) compared with that of the control column.(ABSTRACT TRUNCATED AT 400 WORDS)

Phagocyte-derived lactate stimulates oxygen consumption by Neisseria gonorrhoeae. An unrecognized aspect of the oxygen metabolism of phagocytosis.

O2 consumption resulting from interaction of Neisseria gonorrhoeae and human neutrophils represents a composite of O2 consumed by the two cell systems. Experiments studying the relative contribution of each system suggested the possibility that gonococci increased their metabolic activity in response to interaction with neutrophils. This hypothesis was confirmed by demonstrating that undifferentiated HL-60 cells, which are unable to undergo a respiratory burst, induce a two- to three-fold increase in gonococcal O2 consumption. Gonococcal capacity to adhere to HL-60 cells did not correlate with extent of metabolic stimulation. Stimulatory activity was demonstrable in cell-free supernatant from neutrophils or HL-60 cells, and increased with duration of incubation. Supernatant applied to a G-15 Sephadex column yielded fractions that stimulated gonococcal O2 consumption. Elution profiles were similar for HL-60 cells, neutrophils, and a stimulatory factor previously isolated from pooled human serum. This stimulatory factor(s) failed to adhere to DEAE or C-18 HPLC columns. Stimulatory activity release from myeloid cells was inhibited by incubation at 4 degrees C or in the presence of NaF, indicating a critical role for glucose metabolism. Lactate, the principal product of resting neutrophil glucose catabolism, was demonstrable in cell-free supernatants after incubation at 37 degrees C. Lactate accumulation was inhibited by NaF and decreased temperature of incubation. Lactate at levels present in cell-free supernatant increased gonococcal O2 consumption twofold and restored stimulatory activity to dialyzed serum. Live, but not heat-killed gonococci eliminated lactate released from neutrophils during phagocytosis. Gonococci are able to utilize host-derived lactate to enhance their rate of O2 metabolism.

Increased cytochrome oxidase activity in alkali-burned corneas.

Cytochrome oxidase (CO) activity on alkali-burned rabbit corneas was investigated histochemically to determine the metabolic change in inflamed corneas during wound healing. Cryostat sections of chemically burned and mechanically scraped corneas were stained for CO activity, which is regarded as an index of metabolic activity. Following chemical injury, positive CO activity was detected initially in the vascular endothelial cells of limbal blood vessels. Numerous active polymorphonuclear leukocytes (PMNs) and monocytes were found intravascularly and perivascularly. Fibroblasts that appeared at the wound site exhibited marked CO activity around the limbus. Over a period of 13 days, PMNs gradually invaded the central cornea, followed by fibroblasts of high metabolic activity. The areas of PMN infiltration were the same areas in which fibroblasts showed intense staining, suggesting that a PMN-derived mediator or secondary products might affect the activation of fibroblasts. Epithelial resurfacing was delayed in the chemically burned corneas, although reepithelialization was completed within two to three days in the scraped corneas. Limbal epithelial cells, which recently were suggested as the source of epithelial renewal, showed a remarkable increase of metabolic activity in response to chemical inflammatory stimulation, whereas those in the scraped model did not. This suggests that epithelial cell renewal at the limbus was accelerated in the presence of disturbed reepithelialization.

Baroreflex-linked variations of catecholamine metabolism in the caudal ventrolateral medulla: an in vivo electrochemical study

In vivo electrochemical recordings of the metabolism of catecholamines were obtained in the caudal ventrolateral medulla in anesthetized rats submitted to various experimental changes in systemic arterial pressure. Hypertension induced with phenylephrine and reversal of hypovolemia decreased the catechol metabolic activity. In contrast, controlled or hypovolemic hypotension, induced respectively with sodium nitroprusside or blood withdrawal (30% of blood volume), reversibly elicited the opposite pattern. This was suppressed by deafferentation. The changes in 3atechol metabolic activity in response to hypovolemia were accompanied by similar trends of variations of plasma vasopressin levels. By contrast with the increased catechol metabolic activity secondary to hypotension induced by either prazosin, sodium nitroprusside or hypovolemia, clonidine elicited a decrease in catechol metabolic activity. These data show a dynamic and specific involvement of the metabolism of catecholamines themselves promoted by changes in systemic arterial pressure. This pattern of functioning of catechol metabolism in the caudal ventrolateral medulla appears to be negatively related to systemic arterial pressure changes, a finding which does not fit with the proposed vasodpressor role of the A1-group.

Fluoride stimulation of canine neutrophils: the role of calcium binding.

Neutrophils are known to undergo a burst of metabolic activity in response to particulate and soluble stimuli. Most of these stimuli depend upon calcium in the extracellular medium to exert their maximal effects. We have shown that 24 mM sodium fluoride (NaF) stimulates the metabolic burst in canine neutrophils as measured by chemiluminescence and CO2 formation from the carbon-1 position of glucose. Because these phenomena are calcium dependent, we determined the uptake of calcium by neutrophils activated with NaF. Neutrophils suspended in buffer were incubated with 45CaCl2 and exposed to NaF. This caused an increase in cell-associated calcium from 1.89 ± 0.43 × 10−10 mol/107 cells to 1.06 ± 0.15 × 10−8mol/107 cells in 2 min. In comparison, the calcium ionophore A23187 (10−6M) caused only a modest increase in cell calcium, from 1.89 ± 0.43 × 10−10 mol/107 cells to 4.89 ± 0.85 × 10−10 mol/107 cells. When treated with EGTA (3 mM), NaF-stimulated neutrophils rapidly lost 90% of their cell-associated calcium. Verapamil (3 × 10−4M), a calcium channel blocker, inhibited NaF stimulation of neutrophil metabolism but did not decrease the magnitude or the rate of the calcium association. These studies indicate that the mechanism of NaF stimulation of neutrophils involves massive calcium binding to the external membrane and a subsequent movement of some of this membrane calcium into the cell.

Investigation of alveolar macrophage function using lucigenin-dependent chemiluminescence.

The method using lucigenin-dependent phagocytic chemiluminescence is described for the assessment of alveolar macrophage metabolic activity in response to stimulation by opsonised particles or soluble agents. The requirement for superoxide anion (O2-) in the production of chemiluminescence is suggested by inhibition (95%) using superoxide dismutase. The results obtained are correlated with those obtained using another method of detecting O2- release (r = 0.61; p less than 0.05) and are also related by regression analysis to polymorphonuclear leucocyte contamination of the alveolar macrophage suspension. This shows that alveolar macrophages produce lucigenin-dependent chemiluminescence of the same order of magnitude as do polymorphonuclear leucocytes.

Plasticity of [ 14C]2-deoxy- d-glucose incorporation into neostriatum and related structures in response to dopamine neuron damage and apomorphine replacement

Unilateral injections of 6-hydroxydopamine into the lateral hypothalamus or ventral tegmental area that damage extensively the mesotelencephalic dopaminergic projection result in significant hemispheric asymmetries in autoradiographic labeling after [14C]2-deoxy-D-glucose (2DG) administration. The incorporation of this glucose analog into the ipsilateral neostriatum, nucleus accumbens septi, olfactory tubercle, and central nucleus of amygdala is decreased relative to the contralateral hemisphere. Concurrently, structures receiving projections from the neostriatum (globus pallidus, entopeduncular nucleus, and substantia nigra, pars reticulata) show enhanced labeling in the 6-hydroxydopamine-injected hemisphere, as do diencephalic structures receiving basal ganglia inputs (ventromedial nucleus and ventrolateral portion of the ventral anterolateral complex of thalamus, lateral portion of lateral habenular nucleus). Most of these 6-hydroxydopamine-induced asymmetries of [14C]2DG labelling are abolished or reversed by the injection of apomorphine i.p. (0.25 mg/kg) or directly into the denervated neostriatum (5 microgram) 7--20 days postoperatively. The metabolic effecgs of apomorphine administration are prevented by pretreatment with the dopamine receptor blocking agent, haloperidol (2mg/kg i.p., 2 h before). Thus, this autoradiographic technique can be used to demonstrate neostriatal output circuits that show altered metabolic activity in response to diminished or excessive forebrain dopamine receptor stimulation. The relevance of these findings to: (1) the behavioral abberations resulting from damage to mesotelencephalic dopaminergic systems; and (2) the 'denervation supersensitivity' to DA receptor stimulants is discussed.

Mechanistic model of the growth of Streptococcus cremoris HP at super optimal temperatures

AbstractThe kinetic response of Streptococcus cremoris HP to growth at super optimal temperatures is reported. The response to a step increase in temperature was shown to be transient and to result from an increased metabolic rate caused by the raised temperature combined with thermal deactivation of the cell mass present. The catabolic and anabolic activities of the cell were shown to decay at different rates resulting in an accumulation of cells capable of catabolism (energy production) but unable to reproduce. The proposed mechanism was confirmed by independent estimates of the catabolic and anabolic activities of the culture. A mathematical model based on the proposed mechanism and incorporating simultaneous exponential growth, thermal death, and catabolic uncoupling of anabolically inactive cells was developed. Experimental evaluation of the model indicated the presence of a delay in deactivation of metabolic activity in response to a temperature transient. After the inclusion of this delay in death, it was confirmed that the model was capable of prediction of the balanced growth and transient response of this organism to changes in growth temperature. The delay in death was shown to be of major significance to the control of a simulated cheddar cheese fermentation.

Tumor Cell Respiration Following Irradiation

Oxygen consumption rates for mouse mastocytoma cells examined from 3 to 4 hours after x-irradiation with 250-2000 rads were consistently higher than controls. Cyclic fluctuations in oxygen consumption per cell were dose-dependent; peaks in consumption were generally greater in magnitude and occurred later in time with increasing dose. The cyclic response in consumption is probably due to cell synchronization effects, while the overall higher respiration rates of irradiated cells may reflect increased metabolic activity in response to radiation damage. Oxygen consumption rates for the total cell population were cyclic after 250 and 500 rads, but declined steadily after 1000 or 2000 rads; oxygen consumption rates tended to be lower than controls, especially 12-24 hours postirradiation. Differences between cellular and population oxygen consumption rates reflect changes in cell number after irradiation. It is suggested that postirradiation reoxygenation kinetics in solid tumors may result from changes in tumor oxygen demand.

Effects of sodium transport stimulating substances on enzyme activities in the toad bladder.

The activities of 10 enzymes of mitochondrial and extramitochondrial origin were studied in mucosal homogenates prepared 2 hours after addition of 1×10−8 M dexamethasone to the serosal medium bathing urinary bladders of the toad bufo marinus. The following increases in activity relative to the controls were found: Condensing enzyme +24%; TPN-isocitrate dehydrogenase +21%; glutamate dehydrogenase +23%; glutamate-oxaloacetate transaminase +16%; glyceraldehyde phosphate dehydrogenase +12%; aldolase +15%. The activities of lactate dehydrogenase, malic enzyme, hexokinase, and creatine kinase remained unchanged. Under the same conditions, neither 1×10−9 M dexamethasone, a concentration which has little effect on net sodium transport as measured by short circuit current (scc), nor 1×10−6 M progesterone, which lacks an effect on scc, showed any influence on the activity of the 10 enzymes studied. Vasopressin (25 milliunits per ml serosal medium) did not change the activities of condensing enzyme, isocitrate dehydrogenase, or glutamate dehydrogenase at a time of maximal response of scc (20–50 minutes after administration) while the activities of hexokinase and phosphorylaseb were increased by 9% and 20% at that time. 3′5′-cyclic AMP in combination with theophylline (11 mM) also failed to influence the activities of condensing enzyme, isocitrate dehydrogenase, or glutamate dehydrogenase at a time of maximal stimulation of scc. The results suggest that the toad bladder epithelial cells respond to dexamethasone with an activation of the citric acid cycle, as has been shown with aldosterone. This effect on intramitochondrial enzyme activity is not elicited by two other agents which stimulate sodium transport, namely vasopressin and 3′5′-cyclic-AMP. Therefore the increased activity does not occur as a direct consequence of increased metabolic activity in response to these substances, e.g. to an activation of glycogenolysis and glycolysis. The increased activity of the intramitochondrial enzymes appears to be an independent steroid effect.

The isolation of whole cells from the ciliary epithelium together with some observations on the metabolism of the two cell types

The cells of bovine ciliary epithelium have been isolated from the underlying stroma and separated into pigmented and non-pigmented fractions. Enzymic digestion of the tissue by papain or pronase, followed by collagenase, was required to free the cells from the tissue and, after filtration, the cell suspension was fractionated by centrifugation on a concentration gradient of colloidal silica. The cells were recovered from the gradient in zones which had only a 10% contamination by the minority cell type. In addition to the enzymic method small sheets of non-pigmented cells were obtained from calf eyes by manual dissection. Respiratory and glycolytic activities were determined and both were found to be higher in the non-pigmented cells than in the pigmented cells. Succinate-tetrazolium reductase activity was also found to be higher in the non-pigmented cells, but lactic dehydrogenase was equally distributed in the two types of cell. The rates of respiration and glycolysis of the pigmented cells were, respectively, little affected by succinate and by anaerobic conditions, whereas the non-pigmented cells showed much greater changes in metabolic activity in response to variations in substrate and oxygen supply. These findings lead to the conclusion that it is the non-pigmented cells that play the major role in the provision of energy for sodium transport by the ciliary epithelium.