The competition between two substances for tubular excretion has been demonstrated repeatedly with orthodox clearance techniques. Smith, Goldring, and Chasis (1) found that raising the plasma concentration of diodrast depressed the excretion of phenol red. They concluded that both substances were excreted by the same mechanism. Similarly, it has been reported that intravenously administered dio...

The objective of this experiment was to evaluate the effect of citric acid (CA), phytase and calcium in diets of laying hens on the productive performances and digestibility and excretion of phosphorus (P), calcium and nitrogen (N). An experiment was designed using 24 week old laying hens, which were fed a diet with a base of sorghum and soybean meal containing 2,700 kcal ME/kg, 15% crude prote...

The urinary excretion of orotic acid, an intermediate in the pyrimidine biosynthetic pathway, is markedly increased in many inborn errors of the urea cycle and in a number of other disorders involving arginine metabolism. Carbamoyl phosphate, which accumulates within hepatic mitochondria in patients with ornithine transcarbamoylase deficiency, can diffuse to the cytosol and enter the pyrimidine...

It has been pointed out (1) that, in terms of modern acid-base chemistry, the defects reponsible for the acidosis of renal disease could be: 1) impaired renal excretion of acid in the form of ammonium and titratable acidity, 2) loss of bicarbonate (alkali) in the urine due to a failure of renal bicarbonate conservation or 3) a combination of these two defects. The two main components of urine r...

The endogenous formation of nitrosoproline (NPRO) following administration of nitrate and proline is reported in ten healthy young adults. There was a relatively constant basal excretion of NPRO, 26 +/- 10 (SD) nmol/day, in excess of amounts found in the diet. This basal synthesis of NPRO was not reduced by ascorbic acid (2 g/day) or alpha-tocopherol (400 mg/day). A significant rise in the excr...

Nitrogenous excretion by the terrestrial anomuran crab Birgus latro L. was examined. The main excretory product was uric acid, representing 79-5 % of total excretory nitrogen. It was eliminated as white faeces separate from undigested food material and made up 82-6% of excretory faecal nitrogen. The faeces were the principal route of nitrogenous excretion, accounting for 96-2% of total excretio...