Anomeric compositions of D-glucose in tissues and blood of rat

Summary The anomeric compositions of D-glucose in the liver, kidney, heart, blood and plasma of rat were determined by our method for the assay of D-glucose anomers and the percentages of the -anomer were found to be 61.8, 61.0, 62.4, 62.7 and 62.9, respectively.     

Uptake of D-glucose anomers by rat retina

Summary Uptake ofd-glucose anomers by isolated rat retina was studied. After 3 min incubation at 37°C in the presence of or anomer (750 g/ml), a significantly greater uptake (1.32 mg/g wet tissue) of -anomer was observed compared with that of -d-glucose (1.11 mg/g wet tissue). This result and other data suggest that the carrier ford-glucose transport in the retina prefers the -anomer stereospecifically.Acknowledgment. The authors are grateful to Mr S. Suzuki for his technical assistance.     

Anomeric specificity of glucose-induced somatostatin secretion

In isolated perfused rat pancreases, the alpha-anomer of D-glucose is more potent than beta-D-glucose not solely in stimulating insulin release and suppressing glucagon output, but also in causing somatostatin secretion.     

Sex related fibrinolytic activity in rat tissues

Histochemical study of many organs of male and female adult Wistar rats of the same age showed no difference in fibrinolytic activity (plasminogen activator activity) between the sexes.     

Sex related fibrinolytic activity in rat tissues

Summary Histochemical study of many organs of male and female adult Wistar rats of the same age showed no difference in fibrinolytic activity (plasminogen activator activity) between the sexes.     

Comparative ontogenesis of gamma-glutamyl transpeptidase in rat tissues

Summary In rats, placental gamma glutamyl transpeptidase (GGTP) specific activity declined linearly during the last third of gestation. In contrast, the kidney enzyme activity progressively increased 15-fold. In the gut, peak activity was reached at mid-lactation (age 12 days). Hepatic GGTP levels were maximal during the foetal stage. Brain GGTP was negligible at birth and attained its highest specific activity at weaning.This work was supported in part by USPHS NIH SO8 RR-09128-03.     

Distribution of polyamine oxidase activity in rat tissues and subcellular fractions

The activity of polyamine oxidase (PAO) in rat tissues, and its subcellular distribution, were assayed using a simple polarographic method. The highest PAO activity was measured in the liver and the lowest in the skeletal muscle. In liver, kidney and uterus the highest specific PAO activity was found in the light mitochondrial fraction. PAO was not found in the microsomal fraction except in the kidney.     

Comparison of lysine and tryptophan catabolizing enzymes in rat and bovine tissues

Earlier studies indicate that alpha-aminoadipate aminotransferase (AadAT) and kynurenine aminotransferase (KAT) activities from rat tissues are associated with a single protein. However, our recent studies indicate that AadAT activity from bovine liver and kidney is not associated with KAT activity. To test whether the lysine and tryptophan catabolism in bovine tissues differ from that in rat tissues, we compared the activities of enzymes involved in lysine and tryptophan pathways in rat and bovine tissues. The activities of lysine catabolizing enzymes such as AadAT, lysine alpha-ketoglutarate reductase and saccharopine dehydrogenase in the bovine tissues were significantly lower than those found in rat tissues. The activities of tryptophan catabolizing enzymes such as KAT and kynurenine hydroxylase in the bovine tissues were negligible as compared to those in rat tissues. The results suggest that lysine is degraded via the saccharopine pathway in the livers and kidneys of both species but the metabolism of tryptophan in bovine tissues may be different from that in rat tissues.     

Binding of iron by rat placental tissues

Zusammenfassung Nachweis, dass das Eisenbindungsvermögen der Dottersackplacenta bedeutend grösser ist als bei der chorioallantoiden Placenta und dass diese auch unter der Einwirkung von den Stoffwechsel beeinflussenden Stoffen ein verschiedenes Verhalten zeigt.

---

---

This work was supported by U.S. Public Health Service Grant No. HD05016 and Predoctoral Fellowship Grant No. FO1-DE41063 to R.J.B.G.     

Comparison of lysine and tryptophan catabolizing enzymes in rat and bovine tissues

Summary Earlier studies indicate that -aminoadipate aminotransferase (AadAT) and kynurenine aminotransferase (KAT) activities from rat tissues are associated with a single protein. However, our recent studies indicate that AadAT activity from bovine liver and kidney is not associated with KAT activity. To test whether the lysine and tryptophan catabolism in bovine tissues differ from that in rat tissues, we compared the activities of enzymes involved in lysine and tryptophan pathways in rat and bovine tissues. The activities of lysine catabolizing enzymes such as AadAT, lysine -ketoglutarate reductase and saccharopine dehydrogenase in the bovine tissues were significantly lower than those found in rat tissues. The activities of tryptophan catabolizing enzymes such as KAT and kynurenine hydroxylase in the bovine tissues were negligible as compared to those in rat tissues. The results suggest that lysine is degraded via the saccharopine pathway in the livers and kidneys of both species but the metabolism of tryptophan in bovine tissues may be different from that in rat tissues.Acknowledgments. This work was supported by a grant from the Children's Hospital of Michigan and by a Research Career Development Award from the National Institutes of Health to D. R. Deshmukh.     

The relative distribution of soluble and insoluble cholinesterases in rat excitable tissues

Summary Three ratios were studied here: bound to free AChE (R₁), bound to free BChE (R₂), and the ratios between these two (R₃). The first one proved relevant in that it contributed to the division of the cholinergic tissues into 3 classes: high values (nicotinic tissues: skeletal muscle), low values(muscarinic tissues: small intestine, uterus, heart), and middle values (mixed, nicotinic and muscarinic cholinergic innervation:brain). The third ratio (R₃) showed different values in the muscarinic tissues studied; no significant differences could, however, be found between the ratios of brain and skeletal muscle. Further exploration of this ratio should indicate whether it is of some importance for the characterization of excitable tissues.     

Distribution of polyamine oxidase activity in rat tissues and subcellular fractions.

The activity of polyamine oxidase (PAO) in rat tissues, and its subcellular distribution, were assayed using a simple polarographic method. The highest PAO activity was measured in the liver and the lowest in the skeletal muscle. In liver, kidney and uterus the highest specific PAO activity was found in the light mitochondrial fraction. PAO was not found in the microsomal fraction except in the kidney.     

Stimulation by D-glucose of mitochondrial respiration

Summary D-glucose increases O₂ uptake by cerebellum mitochondria. This effect is abolished by D-glucose-6-phosphate and D-mannoheptulose. It is proposed that the phosphorylation of D-glucose as catalyzed by bound hexokinase directly affects mitochondrial respiration.     

Association of mastopoiesis with haemopoietic tissues in the neonatal rat

Summary Mast cells in the newborn rat occur in haemopoietic foci of liver and spleen, but disappear from those foci as extramedullary haemopoiesis ceases during the initial postnatal month. At the same time, mast cells increasingly populate bone marrow and connective tissues of heart, lung, stomach and portal tract of liver.J. L. D. acknowledges Scholarships from the National Health and Medical Research Council of Australia while working on this project for the degree of B. Sc. (Med.), the University of New South Wales, and subsequently from the National Heart Foundation of Australia.     

Developmental and ageing changes in aminopeptidase activities in selected tissues of the rat

Aminopeptidase activities, assayed as arylamidase activities, were investigated in selected tissues of 1, 6, 12 and 24-month-old rats. The enzyme activities were found to have a heterogeneous distribution and age-related changes were observed. The highest levels of soluble arginyl-aminopeptidase activity were detected in brain homogenate at all the studied ages, whereas membrane-bound activity presented the highest levels in brain and kidney in the four ages tested. Aspartyl-aminopeptidase activity was detected mainly in the particulate fraction of kidney at all four ages. In 1, 6 and 12-month-old animals, soluble aspartyl-aminopeptidase activity was also higher in the kidney than in the rest of the tissues, whereas in the group of 2-year-old rats, the highest levels were found in both kidney and liver. Age-related changes were observed in all the studied tissues and for all the assayed enzymatic activities. In general, the maximal levels were detected in both the youngest and the oldest animals, and the minimal ones in 6 and 12-month-old rats. However, in the adrenals, the soluble and membrane-bound arginyl-aminopeptidase activity was higher in 6-month and 2-year-old rats than in 1-month and 12-month-old rats. These changes may reflect the functional status of the susceptible endogenous substrates of aminopeptidases.     

Stimulation by D-glucose of mitochondrial respiration

D-glucose increases O2 uptake by cerebellum mitochondria. This effect is abolished by D-glucose-6-phosphate and D-mannoheptulose. It is proposed that the phosphorylation of D-glucose as catalyzed by bound hexokinase directly affects mitochondrial respiration.     

Calcitonin: Effect on protein synthesis in different rat tissues

Summary Protein synthesis was inhibited in the pancreas whereas it was enhanced in the kidney and intestine (jejunumileum) after a single injection of porcine calcitonin (20 MRC units/kg b.wt). The incorporation of [³H]leucine into total protein in the brain, heart, liver and stomach did not change after the hormone treatment.Acknowledgment. This work has been achieved at the Institute of Medical Biochemistry, University of Aarhus, Aarhus, Denmark.     

Age- and sex-related differences in the content of prothymosin alpha in rat tissues.

Differences in the tissue content of prothymosin alpha during the early postnatal development of male and female rats are reported. Thymus and spleen have been found to contain significantly higher amounts of prothymosin alpha in the newborn and prepubertal animals, as compared to adults, whereas liver has been found to contain low levels of prothymosin alpha throughout development. These findings indicate a functional association of prothymosin alpha with the proliferating lymphoid tissues of the young rat.