Cholesterol oxidation by rat liver preparations: Effect of age

Résumé On a constaté que les vieux rats synthétisent moins de cholestérine et qu'ils excrètent moins de stéroides acides que les jeunes. Nous avons comparé l'activité de deux systèmes d'enzymes hépatiques chez les jeunes et les vieux rats. Ces systèmes sont la préparation microsomale qui comprend l'activité de la cholestérine 7-hydroxylase, et la préparation mitochondrique qui parvient à oxyder [26-¹⁴C] de cholestérine à¹⁴CO₂. Les deux systèmes qui entrent en jeu dans la synthèse des acides de la bile sont significativement plus actifs dans le foie des jeunes rats.     

Myoglobin in the heart ventricle of tuna and other fishes

Summary The myoglobin content in the hearts of several fishes is positively correlated with the ecological physiology of the species. In the tuna heart, where the highest myoglobin values are found, the logarithmic relationship between myoglobin content and body weight is reported.     

The effect of ferrimyoglobin on the oxidation of succinic acid by horse heart muscle preparations

Riassunto L'autore ha studiato l'azione della metamioglobina sul sistema succinossidasico. È stata riscontrata una netta inibizione che sembra essere specifica per la succinodeidrogenasi. Tale inibizione non è influenzata dall'aggiunta di bleu di metilene ma invece completamente rimossa dal KCN in presenza di bleu di metilene. L'inibizione provocata dalla metamioglobina sulla succinossidasi aumenta nel tempo.

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Aided by a grant of the Rockefeller Foundation and the Consiglio Nazionale delle Ricerche.     

The influence of prostacyclin (PGI2) on contractile properties of isolated right ventricle of rat heart

The mechanism of the positive inotropic effect of prostacyclin (PGI₂) (2.6×10^?6 mol/l) on the isolated right ventricle of rat heart was studied. Our results show that the positive inotropic effect of prostacyclin is produced indirectly through beta adrenoceptors and slow Ca²⁺ channels, because blockade of slow Ca²⁺ channels with verapamil (10^?6 mol/l) and beta adrenoceptors with propranolol (10^?6 mol/l) abolishes this effect. Alpha adrenoceptors do not mediate the action of PGI₂.     

Functional study of the rat olfactory bulb by a 14C-2-deoxyglucose autoradiographic technic]

The autoradiographic method has been used in the Rat to map active regions in the olfactory bulb after a pulse of 14C-2-deoxyglucose with electrical stimulation of the lateral olfactory tract. The highest optical densities were found at the external plexiform, mitral, internal plexiform and granular layers; the lowest was found in the glomerular layer.     

Incorporation of14C-leucine into serum transferrin by slices and cell-free preparations of rat liver

Zusammenfassung Der Einbau von¹⁴C-Leucin in Serumtransferrin in vitro in Leberschnitten und in isolierte Lebermikrosomen der Ratte wurde gezeigt und mit demjenigen in Serumalbumin verglichen. Die gereinigten Proteine wurden immunoelektrophoretisch ausgefällt und ihre Radioaktivität bestimmt. Ebenso wurde die Reindarstellung von Transferrin aus Rattenserum beschrieben.     

Regulation of mitochondrial aconitase by phosphorylation in diabetic rat heart

Mitochondrial dysfunction and protein kinase C (PKC) activation are consistently found in diabetic cardiomyopathy but their relationship remains unclear. This study identified mitochondrial aconitase as a downstream target of PKC activation using immunoblotting and mass spectrometry, and then characterized phosphorylation-induced changes in its activity in hearts from type 1 diabetic rats. PKCβ₂ co-immunoprecipitated with phosphorylated aconitase from mitochondria isolated from diabetic hearts. Augmented phosphorylation of mitochondrial aconitase in diabetic hearts was found to be associated with an increase in its reverse activity (isocitrate to aconitate), while the rate of the forward activity was unchanged. Similar results were obtained on phosphorylation of mitochondrial aconitase by PKCβ₂ in vitro. These results demonstrate the regulation of mitochondrial aconitase activity by PKC-dependent phosphorylation. This may influence the activity of the tricarboxylic acid cycle, and contribute to impaired mitochondrial function and energy metabolism in diabetic hearts. Received 31 October 2008; received after revision 17 December 2008; accepted 2 January 2009     

Sources of metabolic energy used by isolated strips ventricle of frog heart for the uptake and retention of H3-norepinephrine

Resumen La oxidación de substratos endogenos no carbohidratos produce la energia necesaria para obtener un 100% de incorporación y retención de H³NE por el ventriculo aislado de rana. La glicolisis de substratos endogenos produce la necesaria para obtener de un 21–42%. La glucosa exogena no es fuente de energia utilizada para este proceso.     

Activation by S-adenosylhomocysteine of norepinephrine and serotonin in vitro uptake in synaptosomal preparations from rat brain

Summary S-Adenosylhomocysteine (10^–7–10^–5 M) activated norepinephrine (NE) and serotonin (5HT) in vitro uptake in synaptosomal preparations from rat brain, but did not affect dopamine (DA) uptake. When administered to rats (7 mg/kg i.p.), it had the same effect on in vitro NE and 5HT uptake. It did not affect NE and 5HT release.Work achieved within the frame of the research contract institut Mérieux., Institut National des Sciences Appliquées.