[The effect of the pH environment and reduced ATP supply on ATPase activity in the brain of young and adult rats].

On five-day-old and adult Wistar rats (of both sexes) experiments were made where the influence of the pH of the medium was assessed as well as that of a lower ATP supply on the activity of (Na(+)-K+) and Mg++ dependent ATPases (E.C.3.6.1.3.) isolated from tissue of the cerebral cortex and possibly the medulla oblongata. The enzyme activity is expressed in mumol.l-1 of released Pi (minute/mg protein). It was found that the drop of pH of the incubation medium (adjusted with HCl) to 7.0 and 6.4 (as compared with pH 7.4 in control measurements) did not cause in 5-day-old rats a significant change in the activity of ouabain sensitive ATPase of the cerebral cortex or medulla oblongata, while in adult rats a marked reduction was observed. At pH 6.4 in adult rats a greater drop of the activity in the cerebral cortex than in tissue of the medulla oblongata was demonstrated. Equally resistant was also ouabain sensitive ATPase in 5-day old rats against the ATP concentration of the medium; even a drop by 50% (as compared with control values) did not cause a significant reduction of activity, while in adult rats a significant drop was observed. In ouabain sensitive ATPase the position is different. In 5-day-old rats a lower pH reduces its activity to an equal extent for pH 7.0 and pH 6.4. In adult rats the activity is also reduced, the reduction being the more marked the more acid the pH of the medium (cerebral cortex).(ABSTRACT TRUNCATED AT 250 WORDS)