Citrate and Pyruvate Concentrations in Bovine Aqueous Humour

Abstract

The results are reported of enzymatic-colorimetric determinations of citrate concentrations in aqueous humour and plasma, and of pyruvate concentrations in aqueous humour from cattle aged from 1 to 10 years. The mean citrate concentration in aqueous humour samples from 32 animals was 86.5 k 16.3 pmolil (mean value k standard deviation). I n plasma samples from 27 animals the mean citrate concentration was 110.3 k 47.2 pmolll. I n aqueous humour samples from 24 of the 32 cattles, the mean pyruvate concentration was 172.6 k35.6 pmolll. Regression analysis revealed a relationship between age and the citrate concentrations in aqueous humour (p < 0.001) and between age and the pyruvate concentrations in aqueous humour (0.05 > p > 0.02), the citrate concentrations rising and the pyruvate concentrations falling with increasing age. No relationship was demonstrated between the plasma citrate concentrations and age (0.50 > p > 0.40).Citrate and pyruvate are important intermediates in energy metabolism. Both metabolites occupy key positions, pyruvate being situated in the EmbdenMeyerhof pathway and citrate in the Krebs citric acid cycle. In glycolysis, pyruvate is converted into lactate. I n addition, pyruvate may be oxidized via the citric acid cycle.

Pyruvate and Citrate Concentrations in Rabbit Aqueous Humour Determined by an Enzymatic Procedure

“…Moreover, the pyruvate and the citrate levels were both found to be considerably lower in oxen than in rabbits (Bruun Laursen 1972). This suggests a difference in metabolic pattern and level between the anterior section of the rabbit eye and that of the bovine eye.…”

“…Unlike bovine aqueous humour, in which the mean pyruvate concentration is about twice as high as the mean citrate concentration, rabbit aqueous humour was found to contain almost equal amounts of pyruvate (mean value 339 pmolll) and citrate (mean value 354 pmolll). Moreover, the pyruvate and the citrate levels were both found to be considerably lower in oxen than in rabbits (Bruun Laursen 1972). This suggests a difference in metabolic pattern and level between the anterior section of the rabbit eye and that of the bovine eye.…”

“…These facts may have contributed towards the magnitudes of the standard deviation, which also might have been less if all the rabbits had been fasting, though the citrate concentrations in bovine aqueous humour were found to be in a great measure independent of the corresponding plasma levels (Bruun Laursen 1972). Variations with regard to the amounts of anterior and posterior aqueous humour in the punctates may contribute towards raising the standard deviations.…”

“…Changes of the pyruvate and citrate concentrations in aqueous humour possibly reflect alterations of the energy metabolism in the anterior eye section. In oxen the pyruvate concentrations have been found to decline and the citrate concentrations to rise with increasing age (Bruun Laursen 1972). By way of comparison, the results will be reported below of determinations of pyruvate, citrate, and in a few instances also glucose concentrations in rabbit aqueous humour.…”

Glucose, Pyruvate, L‐lactate, and Citrate Concentrations in the Aqueous Humour of Fasting Rabbits in Relation to Age

“…the aqueous seem to be widely independent of plasma citrate concentrations (Bruun Laursen (1972) cattle, Bruun Laursen (unpublished) and Bruun Laursen & Lorentzen (1974) man). The age dependencies of glucose and citrate in aqueous render these parameters less fit for estimating the energy metabolism of the anterior eye section in random samples from a rabbit population.…”