Effects of terpenes and tannins on some physiological and biochemical parameters in two species of phalangerid possums (Marsupialia : Phalangeridae)

The common brushtail possum (Trichosurus vulpecula) and the short-eared possum (T. caninus) are closely related but differ in several aspects of their life-history strategy, habitat and diet preferences. Both are generalist herbivores, but T. vulpecula consumes significant amounts of Eucalyptus spp. foliage, while T. caninus instead feeds mainly on Acacia spp. Eucalypt foliage is protected against herbivory by several classes of plant secondary compounds, including terpenes and tannins, while acacia foliage is protected mainly by tannins. We compared the responses of these two possum species to the addition of either sesquiterpenes or a hydrolysable tannin to a basal diet free of these compounds. In both species, sesquiterpenes tended to reduce food intake, and increased plasma concentrations of albumin and decreased concentrations of bicarbonate, the latter consistent with changes in acid–base balance. Tannic acid significantly depressed food intake in both species, and depressed plasma concentrations of total protein, albumin, glucose, sodium and chloride, consistent with dehydration. T. vulpecula increased urinary glucuronic acid excretion three-fold in response to dietary sesquiterpenes but there was no increase in T. caninus. T. vulpecula had five- to six-fold greater plasma concentrations of bilirubin, a potent antioxidant, than did T. caninus across all treatments. Results suggest that T. vulpecula can better withstand the detrimental effects of plant secondary compounds, consistent with its wider spectrum of foods and broader habitat preferences.

A novel technique for the examination of skin biopsies by laser capture microdissection

BACKGROUND

Skin is an inherently heterogeneous tissue, thus the procurement of pure cell populations is critical for the accurate correlation of a molecular profile to a particular cell type or histological location. Laser Capture Microdissection (LCM) permits the efficient procurement of cells and mapping of genetic changes from histologically prepared samples.

METHODS

This paper describes a robust LCM protocol established in our laboratory for the extraction of high quality DNA which sequenced from 100% of microdissected samples without the need for cloning. The unique properties of skin, in particular its strong intercellular adhesive forces, have dictated a significant modification to the normal procedure of tissue preparation to ensure reliable cell procurement.

RESULTS

Using the methods outlined below we were able to precisely map the pattern of genomic mutations in our target gene of interest in normal skin, actinic keratosis and squamous cell carcinoma.

CONCLUSIONS

The capability to select pure cell populations from the skin will revolutionise our ability to understand the processes involved in cutaneous tumourigenesis.

Oxidative insult to human red blood cells induced by free radical initiator AAPH and its inhibition by a commercial antioxidant mixture

This study was carried out to investigate sequel of oxidative insult to human erythrocytes induced by a water-soluble radical initiator, 2,2'-azobis-(amidinopropane) dihydrochloride (AAPH) and the effect of a commercially available mixed antioxidant (Blackmores, BioAce Excel), containing alpha-tocopherol, ascorbic acid, beta-carotene and some herbal extracts (containing grape seed catechins and milk thistle derived silybin), on lipid peroxidation, degradation of membrane proteins and haemolysis. We performed this study in order firstly to clarify aspects of the mechanism of AAPH induced free radical damage in human erythrocytes and secondly to establish in vitro conditions by which the efficacy of mixed antioxidant preparations may fairly and objectively be compared. In the process of oxidation initiated by peroxyl radical, a rapid loss of reduced glutathione occurred in the first 60 min. Formation of thiobarbitric acid-reactive substances indicative of lipid peroxidation increased subsequently and almost reached maximal levels at 180 min before significant apparent degradation of membrane proteins was detected. At this point, a significant haemolysis occurred. This sequence of events is consistent with the idea that haemolysis is a consequence of lipid peroxidation and the degradation of membrane proteins. The mixed commercial antioxidant, which suppressed lipid peroxidation and protected membrane proteins against degradation induced by peroxyl radicals, also effectively delayed AAPH induced haemolysis. The system we describe provides a sound objective basis for the in vitro comparison of the potential efficacy of the hundreds of antioxidant nutritional supplements currently available in the market place.

Oxidative insult in sheep red blood cells induced by T-butyl hydroperoxide: the roles of glutathione and glutathione peroxidase

Three different types of red blood cells (RBC) were used: (i) RBC from sheep having genetically high GSH (ii) RBC from sheep with genetically low GSH and (iii) RBC from high-GSH sheep treated with CDNB to deplete GSH. Incubation of these RBC with t-butyl hydroperoxide (tBHP, 3 mM) for 10 min caused the formation of TBARS, oxidation of haemoglobin and degradation and aggregation of membrane proteins in RBC from low-GSH sheep and GSH-depleted RBC. By contrast, RBC from high-GSH sheep (normal RBC) did not show the degradation and aggregation of membrane proteins within the first 10 min. Dithiothreitol (DTT) was highly effective in preventing the tBHP-mediated oxidation of haemoglobin, the formation of TBARS and the degradation and aggregation of membrane proteins in both normal RBC and low-GSH RBC. However, DTT did not provide protection in GSH-depleted RBC or normal RBCs in the presence of 1.5 mM mercaptosuccinate (MCS), a potent inhibitor of GSH peroxidase (GSHPx). The ability of GSH to prevent the oxidation of haemoglobin and the degradation and aggregation of membrane proteins was abolished in the presence of MCS. These results indicate that the protective function of DTT involves a GSH-dependent mechanism. Both GSH and GSHPx play key roles in this enzymatic system. In the light of the complete protection of RBC against oxidation induced by tBHP in the presence of DTT or GSH, the GSH/GSHPx system appears to act directly as a tBHP scavenger. The activities of four well-known antioxidants, Butylated hydroxytoluene, ascorbate, alpha-tocopherol and desferrioxamine were also tested in this study to cast further light on the role of free radical scavenging in protection from tBHP mediated free radical insult.

Haemolysis of human and sheep red blood cells in glycerol media: the effect of pH and the role of band 3

Haemolysis of red blood cells (RBC) in glycerol media may be measured spectrophotometrically. The haemolytic process in a rapid phase obeys a first order rate law. The rate constant expresses the rate of haemolysis. To gain a better understanding of the mechanism of haemolysis in glycerol media, the effects of pH and band 3 inhibitors on the rate of haemolysis in human and sheep RBC were observed. Over the pH range used (pH 5.8-10.0), the rate of haemolysis decreased with increase in pH in sheep RBC. By contrast, the rate of haemolysis increased from pH 5.8 to 6.4 and decreased above pH 6.4 in human RBC. The different effects of pH on the rate of haemolysis are due to inhibition of glycerol permeability by H(+) in human RBC but not in sheep RBC. This is supported by the different effects of temperature and Cu(2+) on the rate of haemolysis in human and sheep RBC. We did not observe complete inhibition of haemolysis by the classical band 3 inhibitor, 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). Another band 3 inhibitor 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS) showed only weak inhibition. Phenylgloxal (PG), another band 3 inhibitor, had no effect whatsoever on the rate of haemolysis. These results indicate that the anion pathway of band 3 is not the preferred route of transport of glycerol in mammalian RBC.

Glutathione reductase activity and flavin concentration in guinea-pig tissues

Glutathione reductase (GR) activity and flavin concentration were studied in systemic tissues (brain, heart, lung, liver, spleen, stomach, pancreas, muscle, kidney, testis) and blood components (erythrocytes and plasma) from male guinea-pigs. GR activity and the flavin concentration were high in kidney and liver, and low in muscle. GR activity in erythrocytes was found in a range of tissues, but flavin concentration in erythrocytes was lower than in any tissues. GR was saturated with flavin adenine dinucleotide (FAD) in almost all tissues, but not in muscle or erythrocytes.

Lysine and glutamate transport in the erythrocytes of common brushtail possum, Tammar Wallaby and eastern grey, kangaroo

It was recently coincidentally discovered, using 1H NMR spectroscopy, that the erythrocytes of two species of Australian marsupials, Tammar Wallaby (Macropus eugenii) and Bettong (Bettongia penicillata), contain relatively high concentrations of the essential amino acid lysine (Agar NS, Rae CD, Chapman BE, Kuchel PW. Comp Biochem Physiol 1991;99B:575-97). Hence, in the present work the rates of transport of lysine into the erythrocytes from the Common Brushtail Possum (Dactylopsilia trivirgata) and Eastern Grey Kangaroo (Macropus giganteus) (which both have low lysine concentrations), and Tammar Wallaby were studied, to explore the mechanistic basis of this finding. The concentration-dependence of the uptake was studied with lysine alone and in the presence of arginine, which may be a competitor of the transport in some species. In relation to GSH metabolism, glutamate uptake was determined in the presence and absence of Na+. The data was analysed to yield estimates of the maximal velocity (Vmax) and the Km in each of the species. Erythrocytes from Tammar Wallaby lacked saturable lysine transport in contrast to the other two species. The glutamate uptake was normal in all three animals for adequate GSH biosynthesis.

Phospholipid composition of erythrocyte membranes and plasma of mammalian blood including Australian marsupials; quantitative 31P NMR analysis using detergent

The phospholipid classes of erythrocyte membranes and plasma from several domestic animals and marsupials were quantified by 31P NMR using detergents. Washed erythrocyte samples were thoroughly haemolysed by tip-sonication and dissolved in sodium cholate; plasma samples were dissolved in Triton X-100. The species studied were: common wombat (Vombatus ursinus), black-striped wallaby (Macropus dorsalis), bandicoot (Isoodon macrocarpus), Eastern grey kangaroo (Macropus giganteus), Tammar wallaby (Macropus eugenii), sheep (Ovis aries), goat (Capra hircus), cattle (Bos taurus), horse (Equus caballus), dog (Canus familiaris) and rabbit (Orytolagus caniculus). There were considerable species variations in the relative abundance of erythrocyte and plasma phospholipid classes. The variations may be attributed to the habitats and diets of the animals as well as to their phylogenetic differences.

Glutathione removal reveals kinases as common targets for K-Cl cotransport stimulation in sheep erythrocytes

K-Cl cotransport is activated by swelling, lowering of cellular free Mg (Mgi), and thiol modification of erythrocytes. Direct actions by thiol reagents on the K-Cl cotransport complex were separated from indirect effects through nonoxidative changes in cellular glutathione (GSH). We used 1-chloro-2,4-dinitrobenzene (CDNB), which, conjugated to GSH, is extruded from the erythrocyte as a thioether. CDNB caused a small biphasic effect (inhibition and stimulation) on K-Cl cotransport and, at 1 mM, abolished its stimulation by N-ethylmaleimide (NEM), diazenedicarboxylic acid bis[N,N-dimethylamide], methyl methanethiosulfonate, and staurosporine, a kinase inhibitor, independent of the order of treatment. Hence, NEM and other activating-thiol reagents, and perhaps GSH removal itself, target unidentified kinases involved in activation of K-Cl cotransport. CDNB also abrogated K-Cl cotransport stimulation by Mgi depletion independent of the order of treatment, indicating inhibition at a second site nearer to the transporter. Furthermore, CDNB treatment elevated and rendered K-Cl cotransport insensitive to osmotic shrinkage, suggesting uncoupling from the regulator.

Comparative study of the antioxidant defence systems in the erythrocytes of Australian marsupials and monotremes

A comparison of the erythrocyte (RBC) antioxidant metabolites and enzymes in nine marsupial and two monotreme species was carried out. Reduced glutathione (GSH) concentrations were comparable with those reported for other marsupial and eutherian species. An important finding was that the erythrocytes of the southern hairy nosed wombat regenerated GSH faster than the erythrocytes from its close relative, the common wombat. The activities of glutathione-S-transferase, NADH-methaemoglobin reductase, superoxide dismutase, and glutathione peroxidase (GSH-Px), showed similar levels and extents of variation as those observed in other marsupial and eutherian species. Catalase activities in the marsupials were lower than those measured in the two monotreme species and much lower than those reported in eutherian species. A negative correlation, significant at P < 0.05, was observed between GSH-Px and catalase activities in the RBC of the marsupials. Since both these enzymes "detoxify" H2O2, there appears to be a reciprocal relationship between the activities of these enzymes in marsupial RBC.

Comparative erythrocyte metabolism in marsupials and monotremes

Concentrations of ATP and DPG, activities of 10 enzymes and the glycolytic rates were measured in the erythrocytes of 11 species of marsupials and two species of monotremes. Mean DPG concentrations were greater in the erythrocytes of marsupials than those of eutherian mammals. The opposite is true of ATP. Significant findings from the results of enzyme activities were: high activity of hexokinase (7.39 +/- 0.82 EU/g Hb) in the short-beaked echidna, pyruvate kinase (37.49 +/- 1.0 EU/g) Hb in bridled nailtail wallaby and glucose-6-phosphate dehydrogenase (G6PD; 41.66 +/- 1.24 EU/g Hb) in black-striped wallaby. About 6- to 7-fold difference in the activity of G6PD levels between the two species of wombats was confirmed. Glucose phosphate isomerase activity was also shown to be twice as high in the red cells of the common wombat compared with those of the southern hairy nosed wombat. There were wide variations in the glycolytic rate among the species examined.

Antioxidant systems and erythrocyte life-span in mammals

1. Erythrocyte antioxidant systems--superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione peroxidase (GSH-Px), glutathione S-transferase (GST) and glutathione reductase (GR)--were discussed in relation to life-spans in some mammalian species. 2. The erythrocyte life-span of different mammals was found to be correlated with the levels of SOD, GSH-Px and GSH. 3. Data reviewed indicates that the erythrocyte life-span of each species is governed by both the oxygen radical formation and the efficiency of intrinsic antioxidant systems.

Hematology and erythrocyte biochemistry of spectacled hare-wallaby, Lagorchestes conspicillatus (Macropodidae Marsupialia)

Hematology and the red cell enzymes, metabolites, and rates of lactate production were measured in a small marsupial, the spectacled hare-wallaby Lagorchestes conspicillatus. In common with other marsupials of similar body weights, the red cells of this wallaby were found to have low levels of ATP and higher levels of 2,3-diphosphoglycerate (DPG) and produced no lactate when incubated with inosine. One of the five animals examined was suffering from anemia (hematocrit of 22.0% and hemoglobin concentration of 7.2 g/dl compared with the normal values of 46.6% and 15.8 g/dl, respectively); its red cells had almost twice the concentrations of ATP and DPG and had significantly higher activities of several enzymes of the glycolytic pathway.

Relation between reduced glutathione content and Heinz body formation in sheep erythrocytes

To clarify the oxidant defense functions of reduced glutathione (GSH) in erythrocytes, the effect of GSH deficiency on in vitro oxidant defense was studied, using GSH-deficient sheep erythrocytes (low-GSH cells). The formation of Heinz bodies in low-GSH cells was higher than that in high-GSH cells when the cells were incubated with an oxidant drug, acetylphenylhydrazine (APH). Artificial depletion of GSH by 1-chloro-2,4-dinitrobenzene in high-GSH cells resulted in increased Heinz body formation in these cells incubated with APH. Furthermore, high negative correlation was observed between Heinz body formation and GSH content in sheep erythrocytes exposed to APH. These results clearly indicate that erythrocyte GSH is indispensable for erythrocyte defense against oxidative damage induced by APH, and support the previous observations that sheep with low-GSH erythrocytes were more susceptible to oxidative agents than were sheep with high-GSH erythrocytes.

Developmental changes in the erythrocyte metabolism in bandicoot Isoodon macrourus

Activities of 13 different enzymes were measured in the erythrocytes of juvenile and adult bandicoots, Isoodon macrourus. Seven of these enzymes had significantly (p < 0.05 or less) greater activities in the juveniles compared to the adult animals. The activity of one enzyme--phosphofructokinase--was significantly (p < 0.01) lower in the juveniles. However, the activity of NADH-methaemoglobin reductase (MR) was similar in the two groups of animals. The rates of lactate production using four different substrates (glucose, galactose, inosine and adenosine) were also higher in the juveniles. These results indicate that the erythrocytes of juvenile bandicoots are metabolically more active than those of the adult animals and follow the general pattern of higher metabolic activity in the young red cells in eutherian mammals, with possible exception of NADH-MR activity.

Studies on the blood of fallow deer (Dama dama) and red deer (Cervus elaphus): haematology, red cell enzymes, metabolic intermediates and glycolytic rates

1. Blood samples were obtained from fallow deer (Dama dama) and red deer (Cervus elaphus). Basic haematology, red cell enzymes, and metabolic intermediates and the glycolytic rate of the red cells incubated with different substrates were measured. 2. The major findings were (i) the activity of glucose phosphate isomerase was notably high in the red blood cells of the red deer; (ii) red deer cells also utilized adenosine more efficiently than those of fallow deer and (iii) red cells of both species utilized galactose more efficiently than other species of ruminants.

The relationship between reduced glutathione level and glutathione S-transferase activity in sheep erythrocytes

The relationship between reduced glutathione (GSH) level and glutathione S-transferase (GST) activity in erythrocytes was examined, using sheep erythrocytes, which have varying GSH concentrations, and dog erythrocytes with an inherited high concentration of GSH. There was a positive correlation (r = 0.529, p < 0.001) between the GSH level and GST activity in sheep erythrocytes. In dog erythrocytes, the GST activity in high-GSH cells was significantly (p < 0.001) higher than that in normal-GSH cells. These results indicate that the activity of GST in erythrocytes is directly correlated with the intracellular GSH level.

Erythrocyte metabolism in two species of bats: common bent-wing bat (Miniopterus schreibersii) and red fruit bat (Pteropus scapulatus)

1. Metabolic intermediates, substrate utilization and enzyme activities were determined in the red blood cells of the common bent-wing bat and the red fruit bat. Standard haematological parameters and oxy-haemoglobin dissociation curves were also determined in both species. 2. The glycolytic rate as measured by lactate production was much higher for all substrates in the bent-wing bats. The activities of the glycolytic enzymes were also much higher in this species. 3. The standard haematological parameters were similar for the two species. The levels of 2,3-diphosphoglycerate (DPG) in the red cells of the fruit bat were nearly twice as high as those in the bent-wing bats. 4. The oxy-haemoglobin dissociation curve for the red fruit bat was located to the right of that for the bent-wing bat and both these curves were located to the right of that normally seen for human blood. 5. Both species of bat show blood characteristics well adapted to carrying the increased oxygen demands of flight.

Hemolytic and microbicidal actions of diethyldithiocarbamic acid

Micromolar concentrations of diethyldithiocarbamic acid (DDC) kill fungi, bacteria and malaria. DDC forms chelates with copper and the microbicidal effectiveness of this drug is enhanced greatly by small amounts of copper. DDC, in the presence of at least 1 molar equivalent of copper, also causes lysis of human erythrocytes. To explore the cytocidal actions of DDC and copper, we have used human erythrocytes and Escherichia coli as models. We found that: (1) the combination of DDC and copper also lysed E. coli spheroplasts, suggesting a possible common mechanism of hemolytic and microbicidal action; (2) higher ratios of drug: metal (greater than 4:1) diminished hemolytic and, as observed earlier, microbicidal effects; (3) cobalt, known to suppress the microbicidal effects of DDC:Cu, also prevented red cell lysis; (4) despite the necessary involvement of copper in DDC-mediated hemolysis, there was no evidence of oxidative damage to erythrocytes, and both lysis of erythrocytes and killing of E. coli were undiminished in the absence of oxygen; (5) the DDC:Cu chelate preferentially located in organic solvents and in membranes of erythrocytes. The chelate was quite soluble in chloroform but much less so in a C-16 hydrocarbon (hexadecane) which resembled erythrocyte membrane lipid. In hexadecane and at greater than 10(-4) M DDC and 5 x 10(-5) copper, an amphipathic drug:metal complex accumulated at the organic:aqueous interface; and (6) this amphipathic complex may permeabilize the lipid bilayer, causing leakage of ions and cell water and eventuating in colloid osmotic lysis. Red cells and E. coli exposed to the chelate showed early loss of intracellular rubidium (86Rb+). Furthermore, lysis of erythrocytes and E. coli spheroplasts was suppressed by the inclusion of either dextran or sucrose. Thus, it appears that DDC:Cu chelates are cytocidal by virtue of concentrating in the lipid bilayer and, perhaps, forming amphipathic complexes which disrupt membrane integrity. Drugs with similar behavior hold promise for therapy of malaria because metals capable of forming such complexes may accumulate within parasitized red cells.

Red-Cell Metabolism in the Brown Antechinus, the Bilby and the Rufous Hare-Wallaby

Standard haematological parameters measured in the bilby (Macrotis lagotis) and the rufous hare-wallaby (Lagorchestes hirsutus) were not markedly different. Both species had very high levels of red blood cell 2,3-diphosphoglycerate, whilst the levels of adenosine triphosphate were within the range of most marsupials and mammals. The activities of red-cell enzymes were measured in these two species as well as in the brown antechinus (Antechinus stuartii). Some significant findings were (i) very high levels of hexokinase, glyceraldehyde phosphate dehydrogenase and lactate dehydrogenase in the antechinus and (ii) very high levels of glucose-6-phosphate dehydrogenase and glutathione peroxidase in the rufous hare-wallaby. The glycolytic rate, measured as the amount of lactate produced by the red cells incubated with eight different substrates, was found to be generally higher in the antechinus than in the other two species. The maximum rate of glycolysis was observed with mannose whilst galactose was a poor substrate in all three species.

1H NMR spectroscopic survey of plasma and erythrocytes from selected marsupials and domestic animals of Australia

1. 1H NMR spectra were acquired from whole plasma, intact erythrocytes, and ultrafiltrates of erythrocytes from nine native and eight introduced (domestic) Australian animals; single-pulse, spin-echo and 2-dimensional spectra were obtained. The aim was to detect and at least semi-quantify metabolites in the samples and compare the profiles amongst the species. 2. The Australian natives that were studied were all marsupials: greater brown bandicoot; bettong; eastern grey kangaroo; red kangaroo; koala; possum; red necked pademelon; Tammar wallaby; and wombat. The introduced mammals that were studied were: cat; cattle; dog; goat; horse; pig; rabbit; and sheep. 3. Because of the range of habitats and diets amongst the animals, it was postulated that the concentrations of the common metabolites in the blood would show marked differences and that there would also be some metabolites that were peculiar to a given animal. There were several major differences in the spectra: in the spectra of plasma, the glycoprotein and lipoprotein resonances showed the largest inter-species variation, whereas the most dramatic finding from the spectra of erythrocytes was a very high concentration of lysine in the cells from the Tammar wallaby.

Erythrocyte biochemistry of the grey-headed fruit bat (Pteropus poliocephalus)

1. Several haematological and biochemical parameters were measured in the erythrocytes of the grey-headed fruit bat. 2. The level of 2,3-diphosphoglycerate was almost twice that found in human erythrocytes. Similarly pyruvate kinase activity was more than twice that of man. 3. The activities of other enzymes of the glycolytic pathway were similar to those found in man. 4. The level of reduced glutathione (GSH) and the GSH regeneration rate in the erythrocytes of the bat were comparable to those found in man.

NADH-methemoglobin reductase activity in the erythrocytes of newborn and adult mammals

NADH-MR activity was measured in the erythrocytes of newborn and adult horses, pigs, cattle, sheep, goats, red kangaroos, fruit bats, rats, mice, rabbits and humans. Our results fail to support an earlier hypothesis that higher NADH-MR activity may be an adaptation to increased ruminal nitrite production leading to accelerated oxidation of fetal hemoglobin.

Erythrocyte catalase. A somatic oxidant defense?

Mammalian erythrocytes have large amounts of catalase, an enzyme which catabolizes hydrogen peroxide (H2O2). Because catalase has a low affinity for H2O2, others have suggested that glutathione peroxidase clears most H2O2 within the erythrocyte and that catalase is of little import. We hypothesized that erythrocyte catalase might function to protect heterologous somatic cells against challenge by high levels of exogenous H2O2 (e.g., in areas of inflammation). We find that, whereas nucleated cells (L1210 murine leukemia) are readily killed by an enzymatically generated flux of superoxide (and, therefore, H2O2), the addition of human and murine erythrocytes blocks lethal damage to the target cells. Inhibition of erythrocyte superoxide dismutase, depletion of glutathione, and lysis of the erythrocytes do not diminish this protection. However, inhibition of erythrocyte catalase abrogates the protective effect and the addition of purified catalase (but not superoxide dismutase) restores it. Furthermore, erythrocytes derived from congenitally hypocatalasemic mice (in which other antioxidant systems are intact) do not protect L1210 cells. Our results raise the possibility that the erythrocyte may serve as protection against by-products of its own cargo, oxygen.

Comparative red blood cell metabolism in three wallaby species, Macropus eugenii, Macropus parma and Thylogale thetis (Macropodidae: Marsupialia)

Aspects of red blood cell metabolism were compared among three species of small macropodid marsupials from different habitats. Packed cell volume (PCV), erythrocyte reduced glutathione (GSH) concentration and GSH regeneration rates were similar in all three species. The Parma wallaby had very low red cell potassium levels compared to the other species studied. The Tammar wallaby had higher rates of glucose consumption and lactate production in vitro at both pH 7.4 and 8.2 than did the Parma and significantly lower adenosine triphosphate (ATP) levels than the other species. These findings are consistent with preliminary reports published previously. The differences noted cannot be directly related to differences in the habitats of the species.

Red cell metabolism: a comparative study of some mammalian species

The activities of six enzymes--glucose-6-phosphate dehydrogenase (G-6-PD), 6-phosphogluconate dehydrogenase (6-PGD), glutathione reductase (GR), glutathione peroxidase (GSH-Px), catalase and superoxide dismutase (SOD)--and levels of reduced glutathione (GSH) and GSH regeneration rates were measured in the red blood cells of eight mammalian species--rabbit, guinea-pig, rat, golden hamster, sheep, goat, cattle and human. The results show that whereas the activities of G-6-PD, 6-PGD and GR are widely different among the experimental animals, there is no such variation in the activity of SOD. There does not appear to be a relationship between GSH regeneration rate and the activities of G-6-PD, 6-PGD and GR--the enzymes associated with GSH metabolism.

The effect of experimental anaemia on red cell glutathione reductase

The effect of experimental anaemia on red cell glutathione reductase (GR) was investigated in rabbits, guinea-pigs and cattle. The ratio of active and inactive forms of GR did not change during the experimental period in either the rabbits or the cattle. However, there was a marked rise in the ratio of inactive form in the guinea-pigs during anaemia. It appears that, in addition to the most important regulator of GR activity, namely the flavin content of the red blood cells, there are other mechanisms which are operating in the red blood cells of anaemic animals and that these mechanisms vary among different species of animals.

Effects of genotype and maternal alcohol consumption on some biochemical parameters of red blood cells in the progeny of mice

Effects of genotype and ethanol consumption by pregnant mothers on hemoglobin (Hb) and red-cell levels of adenosine triphosphate (ATP), 2,3-diphosphoglycerate (DPG), and glutathione (GSH) of their progeny were studied in mice. Three lines of mice were used, one selected for high body weight, another selected for low body weight, and an unselected control. An ethanol solution [10% (v/v)] was given ad lib to the females at the time of joining them with males and continued through the pregnancy. Another group received distilled water for drinking throughout. Blood samples from the progeny of both these groups were taken at 10 weeks of age and analyzed for Hb, ATP, DPG, and GSH levels. Alcohol drinking during pregnancy resulted in lower levels of DPG in the red blood cells of progeny of the lines selected for high and low body weight and the reverse in the unselected line. Maternal alcohol consumption had no effect on Hb, APT, and GSH levels in the red blood cells of the progeny of any of the three lines. Females of both selected lines had higher levels of DPG than males. Artificial selection for body weight resulted in a positively correlated response in the level of red-cell DPG and GSH in the progeny.

Glutathione peroxidase, superoxide dismutase and catalase in the red blood cells of GSH-normal and GSH-deficient sheep

Levels of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase were measured in the red blood cells of glutathione(GSH)-normal and GSH-deficient sheep. There were no significant differences in any of the 3 enzyme activities measured in the 2 groups of sheep. Also, there was no relationship between GSH level and the enzyme activity. These results suggest that inspite of large differences in GSH levels, the red blood cells from GSH-normal and GSH-deficient Merino sheep appear to have similar response to oxidative stress against which GSH is credited to play a major role.

Effect of anaemia on red cell metabolism in cattle

Six enzymes: glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), glutathione reductase (GR), glutathione peroxidase (GSHPx), catalase and superoxide dismutase (SOD), and three metabolites: 2,3-diphosphoglycerate (DPG), adenosine triphosphate (ATP) and reduced glutathione (GSH), were measured in the red blood cells of cattle during experimental anaemia. There was a significant rise in the mean levels of DPG (from 0.85 to 1.69 mumol/gHb) and ATP (from 2.16 to 3.25 mumol/gHb) in the early phase of recovery. Enzyme activities also increased during the early recovery period.

2-Deoxyglucose as a substrate for glutathione regeneration in human and ruminant red blood cells

2-Deoxyglucose was found to be a substrate for the regeneration of GSH from GSSG in the red blood cells of humans, sheep, goats and cattle. The regeneration rate with 2-deoxyglucose varied from 15 to 56% of the rate with glucose. It is likely that 2-deoxyglucose is phosphorylated to 2-deoxyglucose-6-phosphate by HK and is then oxidized to 2-deoxygluconate-6-phosphate by G6PD. The latter reaction would produce the NADPH required for GSH regeneration.

Red cell metabolism in buffaloes and camels

Red cell GSH, GSH regeneration rates, and the activities of ten enzymes were measured in the red blood cells of camels and buffaloes. The activity of G6PD was found to be much higher in both the species compared to that found in other ruminants such as sheep, goats, and cattle. Although there were no significant differences in the level of red cell GSH in the two species, there was a striking differences in the rate of GSH regeneration, the mean rate of 0.162 +/- 0.009 mumoles/min/gHb in the camels was significantly higher than the 0.082 +/- 0.011 mumoles/min/gHb observed in the buffaloes.

Glutathione and 2,3-diphosphoglycerate in the blood of hypoxic ruminants

Two merino sheep and two angora goats were subjected to simulated altitudes of up to 5500 m for about 10 h per day for 38 days. Packed cell volume (PCV), haemoglobin (Hb) concentration and red blood cell (RBC) levels of reduced glutathione (GSH) and 2,3-diphosphoglycerate (2,3-DPG) were measured at regular intervals. Mean PCV increased from 33 per cent to 60 per cent in the sheep and from 33 per cent to 45 per cent in the goats. Mean Hb concentration rose from 11.7 g/dl to 23.1 g/dl in the sheep, and from 11.4 g/dl to 16.0 g/dl in the goats. The level of GSH began to rise in the sheep only after the animals were no longer being subjected to the hypoxic stress, increasing by about 20 mg/dl RBC. In the goats, the levels of GSH rose during, as well as after, the period of hypoxic stress, also by about 20 mg/dl RBC. No change in 2,3-DPG levels was found in either species.

Effect of halothane and enflurane anaesthesia on the level of reduced glutathione in human red blood cells

No significant changes were found in packed cell volume, haemoglobin concentration and red cell glutathione levels in patients before and after anaesthesia with halothane or enflurane. These results, though unable to explain the mechanism, support the earlier suggestion that glutathione plays little, if any, role in protecting liver against toxic effects of these anaesthetic agents or their metabolites.