The urea tests of renal efficiency commonly mentioned in the literature include (a) simple estimation of blood urea concentration, (b) determination of urine urea concentration following ingestion of urea, and (c) observations on the relationship between blood and urine urea concentrations. From a comparative study of these three methods, the general conclusion reached in this hospital (1) was ...

Nitrogenous waste excretion in resting dogfish occurred largely (>90 %) as urea-nitrogen (urea-N) efflux across the gills, with a very small urea efflux via the kidney. Ammonia excretion, almost entirely at the gills, accounted for less than 3 % of total nitrogen excretion. Given the extremely high blood urea levels (approximately 640 mmol-N l-1) 'retained' for osmoregulation, and blood ammonia...

The effect of hyperosmotic solution of NaCl, urea and mannitol on Bufo viridis red blood cells were studied. The percentage of water content in B. viridis red blood cells decreased significantly in NaCl and mannitol hypertonic solutions compared to urea hypertonic solution. The urea concentration found in red blood cells in a urea hypertonic solution was significantly higher than in red blood c...

The observation was made some 6 years ago that chickens were not poisoned by the parenteral injection of large quantities of crystalline urease, unless urea was also injected (1). However, rabbits were killed after urease was injected when the blood ammonia nitrogen reached a value of 5 mg. per 100 cc. (2). These observations offer sufficient evidence to make many of the values reported for ure...

Ammonia is the chief excretory product in fishes. However, non-availability of enough of water in the habitat, may lead to the formation of urea, in fishes. In the present study, the possible role of urea formation to avoid the toxicity of ammonia under water-restricted condition was tested in Channa gachua. Circulatory urea and ammonia were estimated in the blood of the fishes and glu...

Ammonia is the chief excretory product in fishes. However, non-availability of enough of water in the habitat, may lead to the formation of urea, in fishes. In the present study, the possible role of urea formation to avoid the toxicity of ammonia under water-restricted condition was tested in Channa gachua. Circulatory urea and ammonia were estimated in the blood of the fishes and glu...

HOUPT, T. RICHARD, AND KATHERINE A. HOUPT. Transfer of urea nitro,gen across the rumen wall. Am. J. Physiol. 2 1 /t(6) : 1296-1303. 1968.-Net movement of urea N across the wall of Pavlov-type rumen pouches was measured in three goats and one sheep as urea concentration difference between pouch and blood was varied. When urease activity of the rumen epitheliurn was depressed by vigorous rinsing ...

Urea is the principal nitrogenous waste product of metabolism and is generated from protein breakdown. It is eliminated from the body almost exclusively by the kidneys in urine, and measurement of its concentration, first in urine and later in blood, has had clinical application in the assessment of kidney (renal) function for well over 150 years. This is the first of two articles that together...

To evaluate the effects of treating or supplementing common reed (Phragmites australis) with 2% urea on intake, nutrient apparent digestibility, and blood metabolites, fifteen Baluchi rams (35.4±2.3 kg body weight) were used in a completely randomized design. Treatments were as follows: 1) common reed, 2) common reed supplemented with 2% urea solution at feeding, and 3) common reed tre...

Most of the methods for the determination of urea in blood involve the use of the enzyme urease to hydrolyze the urea, since this reaction is specific. However, instead of crystalline urease (l), crude jack bean meal extracts are used. These extracts have been found to contain other enzymes besides urease, termed “ammonia-producing” enzymes, and their substrates, which may produce large quantit...