Rate of cerebral ATP utilization in rats

Abstract

The rate of adenosinetriphosphate (ATP) disappearance in the brain after inhibition of aerobic and anaerobic metabolism was investigated. It was found that the rate increases with increasing age in the neonatal rat and that the effect of lowering the body temperature, which slows the rate, is greater in the 21-day rat than in the newborn. Calculation from the data gives 0.5 µm/sec/gm as the rate of high-energy phosphate utilization in the 21-day rat, and 0.04 µm/sec/gm in the 1-day rat. This increase in the rate of energy utilization during neonatal maturation is compared with the capacity to generate ATP; the utilization increase is found to be six times that of the capacity to generate ATP. The Q10 of the high-energy phosphate utilization in the 21-day rat is 1.7 in the 37°–25°C range, but is 10. in the 25°–15°C range. It is concluded that the rate of high-energy phosphate utilization is closely related to the amount of neuronal activity and, further, that the energy cost per average nerve impulse probably is greater in the adult brain than in the neonatal brain.

Changes in brain phosphorus metabolites during the post‐natal development of the rat.

“…With this method, any changes in triphosphate concentration with age will influence the result. However, it changes only slightly or not at all with age (Samson et al 1960;Miller & Shamban, 1977;Mandel & Edel-Harth, 1966). The scatter seen in our results can largely be accounted for by the reproducibility of our method.…”

“…This peak was chosen for two reasons. First, other studies have indicated that ATP and NTP do not change greatly with age (Samson, Balfour & Dahl, 1960;Mandel & Edel-Harth, 1966;Miller & Shamban, 1977). Secondly, ATP concentration is maintained constant during the course ofan experiment by PCr acting as a buffer (see e.g.…”

Acidosis and blockade of orthodromic responses caused by anoxia in rat hippocampal slices at different temperatures.

“…Anoxia in the absence of glucose Because the mammalian brain has little in the way of glycogen reserves, and there is no significant alternative to the glycolytic pathway for the production of ATP (Himwich, 1951;Samson et al 1960;Cohen, 1973;Siesj6, 1978), anoxic acidosis should greatly diminish or even disappear when glucose is removed (Hochachka & Mommsen, 1983;Siesj6 & Wieloch, 1985).…”

“…We therefore compared pHo changes with the simultaneous depression of synaptically evoked population spikes elicited by anoxia, over a wide range of temperatures, because this greatly affects anoxic phenomena as well as underlying disturbances of metabolism (Himwich, 1951; Samson, Balfour & Dahl, 1960;Tanimoto & Okada, 1987, etc.). These findings have been reported briefly (Krnjevi6 & Walz, 1989).…”

Age-Related Differences in the in vitro Rat Hippocampus

“…Clearly there are such differences, since the decapitated heads of young rats continue to make gasping motions for much longer periods of time than do those of adults [3], What appears to be the single most important age-related difference is the lower cerebral metabolic rate of the young. Estimates of the rate of utilization of energy substrates in the brains of young rats range between 5-10% of those for adults (3,9,11], The metabolic rate increases throughout de velopment, and appears to mirror the decreas ed anoxic survivability which is observed. Thus, the increased survivability of the young is not due to an ability to produce more highenergy phosphate compounds via anaerobic glycolysis, but rather to a much smaller de mand for metabolic energy which must be supplied to the nervous system, a demand which steadily increases with age.…”