Effect of temperature on the activity of AMP-deaminase from rat heart

Summary In the presence of 1 mM ATP, the plots of Michaelis dependence of the reaction catalysed by AMP-deaminase from rat heart were hyperbolic at all temperatures between 10 and 40°C. Calculation of the energy of activation for ATP-activated enzyme and of the enzyme-substrate complex formation is presented.     

Effect of temperature on the activity of AMP-deaminase from rat heart.

In the presence of 1 mM ATP, the plots of Michaelis dependence of the reaction catalysed by AMP-deaminase from rat heart were hyperbolic at all temperatures between 10 and 40 degrees C. Calculation of the energy of activation for ATP-activated enzyme and of the enzyme-substrate complex formation is presented.     

Effect of stress on choline acetyltransferase activity of the brain and the adrenal of the rat

Choline acetyltransferase (ChAT) activity was determined in cerebral cortex, hypothalamus, hippocampus, cerebellum, medulla oblongata, midbrain and adrenal gland of rats exposed to acute or chronic stress. The exposure of animals to acute immobilization and cold stress (4°C) for one hour resulted in a significant decline of ChAT activity in all brain regions examined except for the medulla oblongata. Moreover, the exposure to acute stress resulted in significant increase of the same enzyme in the adrenal gland. However, chronic exposure of animals to cold stress (4°C) for 7 days resulted in no significant changes of ChAT activity in all tissues examined except for a decline in the midbrain and an increase in the medulla oblongata. The administration of corticosterone (2.0 mg/kg) 1 h prior to sacrificing caused an effect similar to that of acute stress on ChAT activity in all brain regions except for the hypothalamus and the cerebellum. It was concluded from this experiment that stress-induced changes in the ChAT activity of specific brain regions might be mediated by the adrenal steroids.This work was supported by a grant from the National Aeronautics and Space Administration (NSG 2183 and NAG 2-411), a grant from the National Institutes of Health (NIH RR 0811) and a grant from the Division of Research Resources (NIH grant RR 03020).     

Effect of stress on choline acetyltransferase activity of the brain and the adrenal of the rat.

Choline acetyltransferase (ChAT) activity was determined in cerebral cortex, hypothalamus, hippocampus, cerebellum, medulla oblongata, midbrain and adrenal gland of rats exposed to acute or chronic stress. The exposure of animals to acute immobilization and cold stress (4 degrees C) for one hour resulted in a significant decline of ChAT activity in all brain regions examined except for the medulla oblongata. Moreover, the exposure to acute stress resulted in significant increase of the same enzyme in the adrenal gland. However, chronic exposure of animals to cold stress (4 degrees C) for 7 days resulted in no significant changes of ChAT activity in all tissues examined except for a decline in the midbrain and an increase in the medulla oblongata. The administration of corticosterone (2.0 mg/kg) 1 h prior to sacrificing caused an effect similar to that of acute stress on ChAT activity in all brain regions except for the hypothalamus and the cerebellum. It was concluded from this experiment that stress-induced changes in the ChAT activity of specific brain regions might be mediated by the adrenal steroids.     

Effect of chronic ethanol treatment on peroxisomal acyl-CoA oxidase activity and lipid peroxidation in rat liver and heart

Summary Chronic ethanol administration was shown to increase catalase and acyl-CoA oxidase activities in rat myocardium but did not alter the activity of liver peroxisomal enzymes. As a result of alcohol consumption a 2–3-fold increase in the level of lipid peroxidation was observed in the heart tissue while in the liver the induction was much less pronounced.     

Effect of chronic ethanol treatment on peroxisomal acyl-CoA oxidase activity and lipid peroxidation in rat liver and heart

Chronic ethanol administration was shown to increase catalase and acyl-CoA oxidase activities in rat myocardium but did not alter the activity of liver peroxisomal enzymes. As a result of alcohol consumption a 2-3-fold increase in the level of lipid peroxidation was observed in the heart tissue while in the liver the induction was much less pronounced.     

Effect of phenformin and chlorpropamide on renin activity in the rat

Résumé La phénformine et la chlorpropamide, deux agents antihyperglycémiques, sont utilisés pour le traitement du diabète insipide. Ces deux drogues injectées à des rats diminuent le taux plasmatique de la rénine sans affecter la rénine du rein. La diminution de l'activité rénine plasmatique s'oppose à l'élévation que l'on trouve après injection de diurétiques du groupe chlorothiazide. On suppose que c'est cette élévation, qui produit l'effet antidiurétique de ces drogues dans le diabète insipide. L'activité de la rénine plasmatique ne peut donc expliquer l'effet antidiurétique de tous les composés utilisés dans ce diabète.     

Effect of age on the activity of rat testicular arginine-aminopeptidase

Effects of age on arginine-aminopeptidase activity were investigated in the rat testis. A marked rise of the enzyme activity in 6-week-old rats corresponded to the appearance of spermatids in the later stages of their development.     

The influence of fibrinogen degradation products on the electrobiological activity of the rat heart

Résumé Nous avons constaté que les produits de dégradation de fibrinogène (FDP) dûs à l'action de la plasmine exercent une influence sur les phénomènes électrobiologiques de l'oreillette droite isolée du cur du rat.     

Effect of furosemide on aminopeptidase activity in the rat kidney and urine

Zusammenfassung Histochemische und biochemische Untersuchungen des Verhaltens von Aminopeptidasen nach Furosemidgabe zeigen einen Abfall bzw. Anstieg der Enzymaktivitäten in Nierenschnitten und im Urin von männlichen Wistar-Ratten. Die Resultate weisen auf eine direkte, Furosemid-induzierte reversible Epithelschädigung im proximalen Tubulus hin. Unter gleichen Bedingungen sind entsprechende Befunde bei weiblichen Wistar-Ratten nicht zu erheben.

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Supported by Deutsche Forschungsgemeinschaft.     

Effect of cold exposure on electrophysiological properties of rat heart

Male rats exposed to the cold (4°C) for five or ten days exhibited modifications in their thyroid state, as documented by increases in serum thyroid hormone levels, to which differently graded modifications of heart weight/body weight ratio, heart rate, and resting metabolic rate were associated. The values of the above mentioned thyroid state indicators returned to those of the control when the animals, kept at cold for ten days, were re-exposed to room temperature (24°C) for an additional 10 days. The configuration of action potentials, recorded in vitro at 26°C from fibres of anterior papillary muscles, was different in control rats of different age and was affected by prolonged cold exposure. In fact, the action potential duration (APD) increased after ten days of cold exposure. In the re-exposed group the APD was not different from that of the controls. Such a pattern was not significantly modified when the stimulation frequency increased from 1 Hz to 5 Hz. The above results suggest that in cold exposure, as in experimental hyperthyroidism, thyroid hormone might exert a cardiac chronotropic effect by modifying heart electrophysiological properties. Thus thyroid hormone should play a basic role during the exposure to cold environment, stimulating the body metabolism and increasing heart rate as a response to the requirement for greater tissue perfusion.     

Effect of aminopterin and antibiotics on disaccharidase activity of the rat small bowel

Riassunto Sono state studiate, con tecnica istochimica e con dosaggio enzimatico, alcune disaccaridasi (lattasi, saccarasi, maltasi) nell'intestino di ratto trattato con dosi scalari di antibiotici e antifolici (aminopterina). Si è osservato che il trattamento massivo con tali farmaci altera tutti gli enzimi studiati; il trattamento refratto, in dosi più basse ma per lungo tempo, determina deficit solo della lattasi.     

Effect of thymectomy on lipoprotein lipase activity in the serum and the heart of rats

Zusammenfassung Entfernung der Thymusdrüse führt zu einer Abnahme des Gehaltes an Lipoprotein-Lipase in Serum und Herzmuskel der Ratte. Die Veränderung wird im Verlaufe der ersten 3 postoperativen Wochen als signifikant betrachtet.     

Effect of clofibrate on the enzyme activity of rat liver plasma membranes

Summary The activity of 3 plasma membranes marker enzymes (5-nucleotidase, Mg⁺⁺-ATPase and alkaline phosphodiesterase-I) was determined in plasma membranes isolated from liver of control and of clofibrate-treated rats. A complete identity of plasma membranes enzyme activity in the 2 groups of experimental animals was observed for the 3 enzymes studied.     

Effect of in vivo irradiation of the rat on the taurine concentration of the heart

Summary The taurine concentration in the heart of the rat (moles/g of tissue) was not modified during 10 days after an in vivo irradiation of 900 R.