Concentration of free fatty acids in muscle following administration of corticotropin and hydrocortisone]

Experiments were conducted on rats; the gas chromatographic method was applied to the study of the free fatty acids content in the gastrocnemius 30 minutes after the intraperitoneal injection of adrenocorticotropic hormone (ACTH)--1 Unit per 100 g and hydrocortisone acetate--1 mg per 100 gm of body weight. It was shown that in the resting muscles ACTH increased the content of stearic acid, whereas hydrocortisone--of both stearic oleic acids. The changes in the content of other free fatty acids were insignificant. During the short-term activity the content of stearic acid in the regimen of single rhythmic contractions in the gastrocnemius of intact rats increased. In experiments with ACTH and hydrocortisone this elevation was much less and not significant. ACTH and hydrocortisone stimulated the stearic acid consumption by the muscles during the activity.     

14C] Alanine incorporation into proteins and their contents in the tissue of intact and adrenalectomized rabbits after hydrocortisone and cortitropin administration

A single administration of hydrocortisone to intact rabbits increases the incorporation of [14C] alanine into proteins of the brain and liver tissue homogenates and soluble fractions as well as in blood plasma proteins and reduces the label incorporation into the brain tissue proteins and reduces its incorporation into the blood plasma proteins. Adrenalcetomy is followed by an increase in the incorporation of [14C] alanine into proteins of the brain and muscle tissue homogenates and soluble fraction and into proteins of blood plasma and liver tissue homogenates as well as by reducing the label incorporation into the spleen soluble fraction proteins. ACTH administered to adrenalectomized rabbits reduces incorporation of [14C] alanine into the brain and muscle tissue proteins, total proteins of liver tissue homogenate and increases it into the proteins of the spleen tissue soluble fraction. Multiple administration of the soluble fraction hormones both to intact and adrenalectomized rabbits inhibits the label incorporation into the studied tissue proteins. Parallel with the change in [14C] alanine incorporation into proteins under the hormones effect certain shifts in their contents were also established.     

Distribution pattern of alanine aminotransferase activity in rat liver

Activities of the alanine aminotransferase were measured along the entire sinusoidal paths (1) between small portal tracts and central veins and (2) between regions of adjoining septal branches and central veins in the livers of male Wistar rats using a Lowry technique. The established profiles of enzyme activity give support to previous studies, suggesting functional heterogeneity of liver sinusoids and their abutting hepatocytes related to morphological differences of the sinusoidal bed.     

Distribution pattern of alanine aminotransferase activity in rat liver

Summary Activities of the alanine aminotransferase were measured along the entire sinusoidal paths (1) between small portal tracts and central veins and (2) between regions of adjoining septal branches and central veins in the livers of male Wistar rats using a Lowry technique. The established profiles of enzyme activity give support to previous studies, suggesting functional heterogeneity of liver sinusoids and their abutting hepatocytes related to morphological differences of the sinusoidal bed.Dedicated to Professor Dr. T.H. Schiebler on occasion of his 65th birthdaySupported by grants of the Forschungsförderung des Landes Nordrhein-Westfalen, No. 40002585 and the Verein der Förderer und Freunded der Universität Köln     

Aspartate aminotransferase activity during early development of chicken embryo.

Aspartate aminotransferase (AAT) activity is studied, employing two different procedures, during early development stages of chicken embryo. ATT activity is steady from pre-streak to the definitive primitive streak stage after which it suddenly increases as growth proceeds. INH or IIH administration in this embryonic system led to almost instantaneous and complete disappearance of AAT activity which could be reversed to 80 percent by treatment with equimolar pyridoxal phosphate. Histochemical studies from the literature support a view that the period of intense differentiation coincides with an increased RNA content. The present study shows more AAT activity per mg wet embryo during the same development stages. Whether this is due to availability of more aspartic acid for pyrimidine is not clear due to possible presence of two AAT activities, the many competing reactions that can use aspartic acid, and in situ conditions during differentiation.     

Aspartate aminotransferase and glutamate dehydrogenase activity in the rat brain during infrared laser exposure

In experiments in vivo it was shown that upon low-intensity infrared irradiation changes in the activity of main enzymes of glutamic acid metabolism are a function of time of exposure and flux density.     

Qualitatively similar effects of microiontophoretic applications of corticotropin and hydrocortisone in the hippocampal and hypothalamic neurons of rabbits

A comparison was made of the responses of hypothalamic, septal and hippocampal neurons to microionotophoretic applications of corticotropin (ACTH) and hydrocortisone. A reliable positive correlation of medium significance was found in the hippocamp, less pronounced positive correlation in the hypothalamus and no correlation in the septum. The data obtained indicate that the hippocampal and hypothalamic brain structures are characterized by functional similarity of the mechanisms of neuronal sensitivity to each hormonal substance. It is unlikely that the neurophysiological processes participating in the response of nervous cells to ACTH and hydrocortisone applications are similar, this suggestion being supported by the presence of a number of exceptions and absence of the correlation in the septum.     

Aspartate aminotransferase in the brain of the developing rat

The biochemical immaturity of the rat brain at birth has been largely investigated in recent years (see for references, Sperry, 1955, 1962; Himwich, 1962). It has been tempting to relate neurochemical data to older findings on the physiological maturation of the organ.     

Inhibitory effect of glycation on catalytic activity of alanine aminotransferase

Non-enzymatic glycation is a common post-translational modification of tissue and plasma proteins which can impair their functions in living organisms. In this study, the authors have demonstrated for the first time an inhibitory effect of in vitro glycation on the catalytic activity of alanine aminotransferase (ALT, EC 2.6.1.2), a pyridoxal phosphate enzyme with several lysine residues in the molecule. The porcine heart enzyme was incubated with 50 mmol/l D-fructose, D-glucose, D,L-glyceraldehyde, or D-ribose in 0.1 mol/l phosphate buffer (pH 7.4) at 25°C for up to 20 days. The strongest glycation effect was shown by D,L-glyceraldehyde, which caused complete enzyme inhibition within 6 days. After 20 days of incubation, the ALT activity in samples with D-fructose and D-ribose was less than 7% of the initial enzyme activity. A statistically significant effect of D-glucose on the enzymatic activity of ALT was not found. Incubation of ALT with D-fructose, D,L-glyceraldehyde and D-ribose minimized its catalytic activity both in the glycated and non-glycated fractions of the samples. Markedly higher activity was found in the glycated fraction with glucose. The inhibitory effect of glycation of ALT with D-fructose and D-ribose was found to be more intensive in the presence of L-alanine and weaker in the presence of 2-oxoglutarate. The findings suggest that glycation of the e-amino group of Lys313 as a crucial part of the catalytic site of ALT may contribute to ALT inactivation in the presence of glycating sugars. Nevertheless, glycation of lysine residues outside the active center of ALT seems to be primary.     

Effect of corticotropin on the dehydrogenase activity of cells and tissues

The authors studied the effect of native ACTH on dehydrogenase activity of isolated strips of rat diaphragm and suspension of E. coli cells, serotype O III:B4, grown on beef extract agar in a medium with different dehydrogenation substrates. ACTH activated dehydrogenase of rat diaphragm in a medium containing pyruvate, alpha-ketoglutarate, malate, beta-hydroxybutyrate, D-aspartic acid and did not alter it in a medium containing succinate. In contradistinction to rat diaphragm, ACTH activated dehydrogenase of E. coli cells whatever the substrates used (oxaloacetate, isocitrate, alpha-ketoglutarate, succinate, fumarate, malate, pyruvate, lactate, beta-hydroxybutyrate, glucose, D-aspartic acid. Synacthen (ACTH1-24) exerted a similar effect. It is suggested that the effects of ACTH are mediated via its influence on adenylate cyclase in the absence of receptors.     

Capillary electrophoresis assay of alanine:glyoxylate aminotransferase activity in rat liver

We measured hepatic alanine:glyoxylate aminotransferase (AGT) activity using capillary electrophoresis. After rat liver homogenate was incubated in the presence of substrates and pyridoxal 5'-phosphate, the pyruvate and glycine produced by AGT were measured. The AGT activity was 10.02+/-0.31 micro mol pyruvate/h/mg protein and 10.21+/-0.15 micro mol glycine/h/mg protein. This method is relatively simple and shows superior sensitivity, allowing the measurement of enzyme activity in 5 micro g of protein. Therefore, it appears to be suitable for laboratory use and may also have advantages for measuring AGT activity in liver biopsy specimens.     

Identity of alanine:glyoxylate aminotransferase with alanine:2-oxoglutarate aminotransferase in rat liver cytosol

Rat liver soluble fraction contained 3 forms of alanine: glyoxylate aminotransferase. One with a pI of 5.2 and an Mr of approx. 110,000 was found to be identical with cytosolic alanine:2-oxoglutarate aminotransferase. The pI 6.0 enzyme with an Mr of approx. 220,000 was suggested to be from broken mitochondrial alanine:glyoxylate aminotransferase 2 and the pI 8.0 enzyme with an Mr of approx. 80,000 enzyme from broken peroxisomal and mitochondrial alanine:glyoxylate aminotransferase 1. These results suggest that the cytosolic alanine: glyoxylate aminotransferase activity is due to cytosolic alanine: 2-oxoglutarate aminotransferase.