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M Debray

Publications and source records attributed to M Debray.

68 records · Page 4Linked to original sources
PubMed1982

[Study of the binding characteristics of chlorophenoxyisobutyric acid to serum proteins in chronically uremic patients : influence of dialysis and heparine (author's transl)].

The binding characteristics of chlorophenoxyisobutyric acid (CPIB) to serum proteins has been studied in 10 chronically uremic patients and 9 healthy subjects using the technique of equilibrium dialysis. Scatchard analysis of the results indicated a significant decrease in association constants for low as well as for high affinity sites. The number of binding sites however was not diminished thus suggesting the presence of competitive inhibitors. Such inhibitors were dializable, at least in part, as demonstrated by in vivo-hemodialysis and in vitro-dialysis experiments. The in vivo administration of 50 mg heparin intravenously led to a striking increase in the unbound fraction of serum CPIB whereas the addition of 10 IU/ml heparin in vitro induced no change of protein binding which is in favor of only an indirect effect of heparin. In conclusion, CPIB binding to serum proteins of chronically uremic patients as compared to normal volunteers was decreased leading to an increase of its unbound circulating fraction. The observed change of protein binding appeared to be due to the presence of competitive inhibitors in uremic serum.

Binding, Competitive↗
PubMedDate not supplied

Specific modulation of two neuronal digitalis receptors by anaesthesia.

Three isoenzymes of digitalis receptors (alpha 1, alpha 2, alpha 3) in the brain and only one in the kidney (alpha 1) can be distinguished by their ouabain affinities and their responsiveness to sodium. Since we have reported modulations for these digitalis receptors by their fatty acid membrane environment, anaesthesics could bind on and modulate either directly these receptors or indirectly by disturbing membrane lipids. The aim of this study was to evaluate this anaesthetic action on apparent ouabain affinities and sodium dependence of cerebral and renal Na+, K(+)-ATPase isoenzymes activities. Rat brain and kidney membrane fractions with pentobarbital-induced anaesthetized state were compared to an unanaesthetized state for their (1) fatty acid composition of total membrane phospholipids, (2) responsiveness to ouabain and (3) Na+ dependence of digitalis receptors. An anaesthesia period of 10 minutes induced (1) a fatty acid modification of brain membranes and (2) a significant sensibilization to ouabain for the alpha 2 and alpha 3 isoforms of digitalis receptors (alpha 2, IC50; 8.2 +/- 0.5 x 10(-7) mol/l vs 4.5 +/- 0.2 x 10(-7) mol/l; alpha 3, IC50; 6.0 +/- 0.3 x 10(-8) mol/l vs 2.5 +/- 0.1 x 10(-8). In contrast, the ouabain affinity of the alpha 1 subunit expressed in kidney and brain membranes was unaltered. No anaesthetic effect was observed on the Na+ dependence of the alpha 1 isoenzyme in the brain (4 mmol/l) and the kidney (8 mmol/l). Pentobarbital induced a desensibilization for alpha 2-receptors (8.3 +/- 0.5 vs 16.0 +/- 1.4 mmol/l Na+) and a sensibilization for alpha 3-receptors (14.4 +/- 0.8 vs 10 +/- 1.3 mmol/l Na+). These altered properties could be related to a selective modification of the fatty acid composition and/or to the presence of a specific binding site for pentobarbital on these two neuronal digitalis receptors.

Anesthesia↗