The lack of bicuculline and picrotoxin influence on midazolam depressant action on brain oxygen consumption.

In the previous study of the rat frontal cortex slices oxygen consumption (QO2), polarographically determined using the biological oxygen monitor, a moderate respiratory depressant action of midazolam ex vivo (1.0 mg/kg) has been observed. Antagonist of the benzodiazepine binding site, flumazenil, blocked the effect of the agonist. However, midazolam-gamma-aminobutyric acid (GABA) interactions pointed to the possibility that a part of midazolam action is independent of the classical GABA potentiation. To test this presumption, GABAA receptor antagonists bicuculline and picrotoxin were administered. Both blockers antagonized the QO2 reducing effect of the combination of per se effective doses of midazolam (1.0 mg/kg) and GABA (5 x 10(-4) mol/l), as well as of GABA (5 x 10(-4) mol/l) itself. However, neither effects of midazolam (1.0 mg/kg) on its own, nor those of midazolam in presence of the physiological, per se ineffective, concentration of GABA (10(-6) mol/l), were susceptible to antagonism. These results show that ex vivo influence of midazolam on cerebral metabolic activity should be partly ascribed to some of its cellular mechanisms probably associated to the GABA modulation, but distinct from the standard GABA-potentiating effects of benzodiazepines.

[Effect of uremia and peritoneal dialysis on peritoneal mesothelial cells]. / Uticaj uremije i peritoneurske dijalize na celije mezotela peritoneuma.

The aim of the study was to investigate the morphology of mesothelial cells of the peritoneum of patients with terminal renal failure (TRF), taken by the biopsy immediately before the onset of peritonal dialysis (PD), and to compare it with the findings in patients with PD. The samples were prepared in the way standard for light microscopy and transmission electron microscopy. In patients with TRF intracytoplasmatic inclusions could be observed, unusual protrusions of mesothelial apical surfaces, deformation of mesothelial cells and their detachment from the basal membrane, as well as the dilatated cisternae of granulated endoplasmatic reticulum with filamentous structures in some of them. In patients on PD cytoplasmic protrusions of different shapes and contents were observed at the surface of mesothelial cells, multiplication of basal membrane, occurrence of young forms of mesothelial cells as well as the detachment of those cells from the basal lamina.