Mechanism for enterohepatic injury caused by circulatory disturbance of hepatic vessels in the rat

We reported previously that a transient occlusion followed by reperfusion of the portal vein and the hepatic artery of the rat significantly decreased the transhepatic transport of a cholephilic compound, and that this decrease was prevented by pretreating animals with poly(styrene co-maleic acid butyl ester)-conjugated superoxide dismutase (SM-SOD). To elucidate the mechanism for oxidative injury of the liver and the site for the generation of superoxide radicals, the effect of a portosystemic bypass on the liver function was examined in the rat whose hepatic vessels were temporarily occluded. A portosystemic bypass inhibited the reperfusion-induced decrease in hepatic transport of bromosulfophthalein as effectively as did SM-SOD. Kinetic analysis using 125I-labeled albumin revealed that the permeability of the small intestine markedly increased after a transient occlusion. The increase in intestinal permeability was also inhibited either by SM-SOD or by the portosystemic bypass. Xanthine oxidase activity in portal plasma markedly increased during occlusion and reperfusion, while it remained within normal ranges in the bypassed group. Thus, superoxide radical, and/or its metabolite(s), might play a critical role in increasing the intestinal permeability and in the pathogenesis of reperfusion-induced liver injury.     

Effect of vacuolization on the sodium concentration in an isolated muscle fiber]

Using the Perkin Elmer flame photometer sodium and potassium concentrations have been measured in muscle fibers from the m. ileofibularis of Rana temporaria. After 30 minutes preincubation in the Ringer solution, made hypertonic by the addition of 0.22M glycerol, the muscle fibers were incubated in the normal Ringer solution for 30 min. These fibers showed a vacuolation and an increase in total fiber sodium up to 37.2 mmol/l +/- 5.9 S. E., or 45.8 mmol/kg H2O +/- 7.3 S. E. No significant changes in potassium concentration were observed. Then, the fibers were exposed again to the Ringer solution containing 0.22 M glycerol. This procedure caused the disappearance of vacuoles and decrease in fiber sodium concentration down to 17.7 mmol/l +/- 1.6 S. E., or 21.8 mmol/kg H2O +/- 2.0 S. E. The effect of vacuolation was not blocked by ouabain (1.10(-4) M). It is suggested that the vacuoles have a high NaCl concentration. A model for NaCl and water accumulation in T-tubules is presented.     

Effect of buspirone on glutathione hepatic levels in rat

The effect of oral administration of buspirone (0.5-1.0 and 2.0 mg/Kg) on GSH levels was studied in rat liver. The modulating activity of buspirone on hepatic content of this tripeptide is clearly opposite to that of DAZ, put into evidence by us in previous works. Thus our observations let us hypothesize a different mechanism of action for buspirone than that for benzodiazepines.     

Effect of stress on parietal hydrolysis of saccharose in rats]

Experiments were conducted in albino rats of both sexes and different age; a study was made of the activity of the intestinal invertase directly after 4-hour immobilization. There was revealed a depressive effect of stress on the activity of membrane digestion and enzyme production in the intestinal epithelal cells, and a definite dependence of the observed effect on the animals' sex age. The latter was expressed in a greater fall of the invertase activity in young females and in its marked variations in old female rats.