Urea synthesized commercially and formed naturally as a by-product of cellular metabolism is an important source of nitrogen (N) for primary producers in aquatic ecosystems. Although urea is usually present at ambient concentrations below 1 μM-N, it can contribute 50% or more of the total N used by planktonic communities. Urea may be produced intracellularly via purine catabolism and/or the ure...

Urea production rate (Ra) is commonly measured using a primed continuous tracer urea infusion, but the accuracy of this method has not been clearly established in humans. We used intravenous infusions of unlabeled urea to assess the accuracy of this technique in normal, postabsorptive men under the following four different conditions: 1) tracer [13C]urea was infused under basal conditions for 1...

ROCH-RAMEL, FRANCOISE, J. DI~ZI, FRANGOISE CHOM~TY, PIERRETTE MICHOUD, AND G. PETERS. Disposal of large urea overloads by the rat kidney: a micropuncture study. Am. J. Physiol. 2 1 a(6) : 1524-1532. 1970.-In rats overloaded with urea, at plasma concentrations of 60-80 mM, the proximal fractional reabsorption of urea was not impaired, whereas the cortical tissue-to-plasma urea concentration rati...

Urea degradation was measured during 16 experiments in 13 chronic uremic patients being treated with essential amino acids or their analogues. [(14)C]Urea was injected i.v. and the clearance of labeled urea from its volume of distribution was compared with the simultaneous renal clearance of ordinary urea, which averaged 2.0 liters/day. The difference, extrarenal clearance of urea, averaged 3.1...

Four gilts (average BW 80 kg) were used in the first experiment to study the effect of i.v. infusion of urea on urea kinetics by means of a radioisotope dilution technique. The pigs were fed twice daily 600 g of a cornstarch-based diet formulated to contain 16% CP by supplementation with isolated soy protein. Infusion of urea, compared with saline, increased (P < .05) plasma urea concentration,...

We used a perfused gill preparation from dogfish to investigate the origin of low branchial permeability to urea. Urea permeability (14C-urea) was measured simultaneously with diffusional water permeability (3H2O). Permeability coefficients for urea and ammonia in the perfused preparation were almost identical to in vivo values. The permeability coefficient of urea was 0.032 x 10(-6) cm/sec and...

the study was conducted to evaluate the effects of feeding varying levels of ficus sycomorus leaf forages as protein supplements to a basal diet of urea treated maize stover. four yankasa goats averaging one year and weighing 11.7±1.8 kg were used to measure the feed intake, digestibility and nitrogen balance. the basal diet (urea treated maize stover) was supplemented with 0 (t1), 50 (t2), 100...

in order to evaluate the response of quantitative and qualitative characteristics of the isabgol (plantago ovata frosk.) medicinal plant to separate and combined application of urea and biofertilizer an experiment was conducted in a randomized complete block design at the research farm of shahrekord university in 2011. the experimental treatments consisted of control (no urea and biological fer...