In Vivo 31p Nuclear Magnetic Resonance Spectroscopy of Skeletal Muscle Energetics in Endotoxemic Rats: A Prospective, Randomized Study

in Critical Care Medicine (1994), 22(3), 499-505

OBJECTIVE: To identify possible alterations in the skeletal muscle high-energy phosphate metabolism at the early phase of endotoxic shock in rats. DESIGN: A prospective, randomized study of skeletal ... [more ▼]

OBJECTIVE: To identify possible alterations in the skeletal muscle high-energy phosphate metabolism at the early phase of endotoxic shock in rats. DESIGN: A prospective, randomized study of skeletal muscle energetics in endotoxemic and in control rats, by in vivo 31P nuclear magnetic resonance (NMR) spectroscopy at rest, under regional ischemia, and during reperfusion. SETTING: Biochemical NMR laboratory equipped for surgery and hemodynamic monitoring. SUBJECTS: Wistar rats were randomized to different groups. Eight rats were injected with Escherichia coli endotoxin (15 mg/kg, survival time 19 +/- 4 hrs) intraperitoneally. Seven other rats served as controls. The additional nine rats were studied for the saturation recovery pulse sequence. INTERVENTIONS: In the treatment group, endotoxin was injected 8 hrs before NMR spectroscopy. The right hind limbs were studied under anaesthesia using a surface coil NMR probe. Their high-energy phosphate contents and intracellular pH were determined by 31P NMR spectroscopy. After baseline measurements, an ischemia-reperfusion challenge was imposed on the muscle by transient clamping of the abdominal aorta. Contralateral femoral artery pressure was constantly monitored. MEASUREMENTS AND MAIN RESULTS: During the baseline period, the endotoxin-treated muscles did not show any difference in the distribution of the high-energy phosphate compounds or in intracellular pH, as compared with the controls. Ischemia resulted in a significantly faster decline of the inorganic phosphate/creatine phosphate ratio in the endotoxin-treated rats (1.35 +/- 0.17 vs. 0.51 +/- 0.06 at the end of the 38-min ischemic period). Skeletal muscle acidosis developed earlier and was deeper in the endotoxemic animals (pH: 6.94 +/- 0.02 vs. 7.02 +/- 0.03 at the end of ischemia). During reperfusion, the calculated time constants of recovery of inorganic phosphate to phosphocreatine ratios were identical between groups. CONCLUSIONS: Resting nonischemic muscles of endotoxin-treated rats show no evidence of alterations in high-energy phosphate metabolism. However, under ischemic conditions, high-energy phosphate metabolism deteriorates faster in the skeletal muscles of treated animals. These data support the hypothesis of a greater mismatch during perfusion at very low pressure between residual oxygen availability and oxygen needs in the endotoxin-treated muscle cell. [less ▲]

Interrelationship of Hypertension, Plasma Lipids and Atherosclerosis

in Drugs (1988), 36(Suppl 2), 18-26

The relationship between hypertension and atherosclerosis has been illustrated by epidemiological, clinical and experimental observations. Typical atherosclerotic lesions develop in arterial wall when ... [more ▼]

The relationship between hypertension and atherosclerosis has been illustrated by epidemiological, clinical and experimental observations. Typical atherosclerotic lesions develop in arterial wall when hypercholesterolaemia is present. Hypertension aggravates these lesions by causing vascular structural changes. In clinical studies, however, the correction of high blood pressure does not decrease the incidence of coronary heart disease. Several hypotheses have been formulated to account for this observation: one is that reversibility of the structural vascular changes induced by hypertension is not complete when the blood pressure is lowered; another is that antihypertensive drugs have a deleterious effect on the vascular wall. [less ▲]

Que représente l'introduction de la kétansérine pour le traitement de l'hypertension artérielle?

in Revue Médicale de Liège (1988), 43

La fonction rénale au cours de la grossesse normale

in Rein et grossesse (1984)

L'état de gravidité est caractérisé par des modifications remarquables de la fonction rénale. C'est la seule situation clinique ou le flux plasmatique rénal et la filtration glomérulaire augmentent de ... [more ▼]

L'état de gravidité est caractérisé par des modifications remarquables de la fonction rénale. C'est la seule situation clinique ou le flux plasmatique rénal et la filtration glomérulaire augmentent de plus de 50 % pour une période de longue durée. Le mécanisme de ces modifications a largement profite de modèles expérimentaux. Le rôle des secrétions hormonales, et de la synthèse accrue de prostaglandines, caractéristiques de la grossesse parait primordial. Simultanement , on relève chez la femme enceinte des adaptations de la fonction tubulaire qui vont rendre compte d'une excrétion urinaire accrue de glucose, d'acides aminés et d'acide urique. Enfin, la grossesse s'accompagne d'une expansion des espaces extravasculaires. Cette modification est associée a une hypersécrétion de renine, d'aldosterone et de desoxycorticosterone. Parallèlement, on observe une résistance a l'effet vasoconstricteur de l'angiotensine II. Ces altérations paraissent indispensables au deroulement normal de la grossesse et à.un dévéloppement optimal du fœtus. La grossesse se caractérise par des modifications remarquables de la fonction rénale, de l'équilibre hydro-minéral ainsi que des adaptations importantes sur le plan hemodynamique. Ces modifications sont évidemment interdependantes, sans qu'il soit à ce jour aise de définir quelle est l'alteration initiale: rénale , endocrinienne ou cardiovasculaire. Pour des raisons purement pratiques, nous traiterons successivement chacun de ces aspects en insistant chaque fois que cela est possible sur les répercussions d'une altération d'un système sur les deux autres . [less ▲]

Application de la RMN du Na 23 à l'étude des échanges ioniques

in 2nd international symposium fundamentals of technical progress in medicine (1983)

One single line is usually observed in the Na NMR spectra of biological systems. Some anionic paramagnetic species interacting with the sodium shift the sodium signal. So long as it does not enter the ... [more ▼]

One single line is usually observed in the Na NMR spectra of biological systems. Some anionic paramagnetic species interacting with the sodium shift the sodium signal. So long as it does not enter the cell, a shift reagent splits the resonance line into two components: the intra (unshifted) and the extracellular Na (shifted). The method is applied to intestinal epithelium and to erythrocytes. Extracellular medium is enriched with dysprosium tripolyphosphate 2,5 mM. Na-K pump activity is studied in human erythrocytes. Ouabain (10 M) inhibition can be followed by the increase of the internal Na peak on the successive spectra whereas it does not change in the control. Na efflux out of the Na loaded erythrocytes can be measured as well. After incubation in a recovering medium, intracellular Na, as calculated from the successive spectra, returns progressively to normal. Simultaneously, the external peak shift reduces. This method can successfully demonstrate attenuations of the Na-K pump in pathological circumstances, such as chronic renal failure . The effects of polyether antibiotics on the sodium transport are also studied by this way. For instance, monensin causes a swift Na efflux that transiently broadens the external signal. Using shift reagent, Na NMR is an efficient tool for ionic membrane exchange studies. [less ▲]