| Abstrakt: |
Testis tissue from 60 mature rats rendered bilaterally cryptorchid for 0, 2, 4, 8, 12, 16, 20, 28, or 44 days was incubated in specifically labeled glucose or metabolic intermediates. The rate of 14CO2evolution was measured over a 5-hr incubation period. Residual media were assayed for glucose and lactate. In one experiment oxygen uptake was monitored electrically over a 4-hr period in the presence and absence of glucose.Mean recovery of glucose-14C as 14CO2(% recovery/100 mg wet weight/5 hr) fell from 3.98 at 0 days to 0.69 at 12 days. This fall followed closely the fall in testis weight over the same period. At 0 days, oxygen uptake rates (µl/100 mg wet tissue/ hr) over a 4-hr incubation period fell from 92.3 to 43.7 in the presence of glucose and from 87.6 to 17.5 in the absence of glucose. At 12 days, corresponding rates were from 74.6 to 78.7 and from 83.6 to 72.2. Glucose oxidation to 14CO2accounted for 28% of oxygen uptake at 0 days and 5% at 12 days.Relative rates of recovery of 14CO2from specifically labeled glucose carbons were in the order C-3,4 > C-2 > C-6 = C-1 at 0 days and C-1 = C-3,4 > C-6 > C-2 at 44 days. Glucose uptake (µg/100 mg wet tissue/hr) fell from 170 at 0 days to 45 at 8 days, while lactate production remained relatively unchanged. Recovery of gluconate-1-14C2as 14CO2(%/100 mg wet tissue/5 hr) increased from 0.48 at 0 days to 0.93 at 20 days. Oxidation of glucuronate-6-14C remained relatively unchanged. Evolution of 14CO2from acetate-1-14C was doubled by the presence of glucose with both control and cryptorchrid testis tissue, while evolution of 14CO2from glucose-U-14C was reduced in the presence of acetate.It was concluded that in rat testis heat-sensitive germinal cells were the principal site of glucose oxidation and that in these cells glucose was oxidized via the Embden-Meyerhof pathway of glycolysis, decarboxylation, and the citric acid cycle. Small amounts of glucose were oxidized by heat-resistant cells, predominantly via pentose cycle, carboxylation, and the citric acid cycle. |
