scholarly journals Impacts of active urea secretion into pars recta on urine concentration and urea excretion rate

2013 ◽  
Vol 1 (3) ◽  
Author(s):  
Anita T. Layton ◽  
Lise Bankir
Keyword(s):  
Excretion Rate ◽  
Urine Concentration ◽  
Urea Excretion ◽  
Pars Recta

scholarly journals Ureotelism is inducible in the neotropical freshwater Hoplias malabaricus (Teleostei, Erythrinidae)

2004 ◽  
Vol 64 (2) ◽  
pp. 265-271 ◽  
Author(s):  
G. Moraes ◽  
V. L. P. Polez
Keyword(s):  
Specific Activity ◽  
Excretion Rate ◽  
Nitrogen Excretion ◽  
Urea Synthesis ◽  
Plasma Ammonia ◽  
Alkaline Water ◽  
Hoplias Malabaricus ◽  
Urea Excretion ◽  
Ammonia Transport ◽  
In The Wild

Increased environmental pH decreases ammonia transport through the gills, impairing nitrogenous waste. The consequent toxicity is usually drastic to most fishes. A few species are able to synthesize urea as a way to detoxify plasma ammonia. We studied three teleosts of the family Erythrinidae living in distinct environments, and assumed the biochemical behaviors would be different in spite of their being closely related species. Adult fish collected in the wild were submitted to alkaline water and the urea excretion rate was determined. The specific activity of urea cycle enzymes was determined in liver samples of fish from neutral waters. The studied species Hoplias lacerdae, Hoplerithrynus unitaeniatus, and Hoplias malabaricus are ureogenic. Urea synthesis is not a metabolic way to detoxify ammonia in H. lacerdae and Hoplerithrynus unitaeniatus exposed to an alkaline environment. The plasma ammonia profile of both species showed two distinct biochemical responses. Urea excretion of H. malabaricus was high in alkaline water, and the transition to ureotelism is proposed. The nitrogen excretion rate of H. malabaricus was among the highest values reported and the high urea excretion leads us to include this species as ureotelic in alkaline water.

The marble goby oxyeleotris marmoratus activates hepatic glutamine synthetase and detoxifies ammonia to glutamine during air exposure

1999 ◽  
Vol 202 (3) ◽  
pp. 237-245 ◽  
Author(s):  
L.Y. Jow ◽  
S.F. Chew ◽  
C.B. Lim ◽  
P.M. Anderson ◽  
Y.K. Ip
Keyword(s):  
Glutamine Synthetase ◽  
Glutamate Dehydrogenase ◽  
Excretion Rate ◽  
Ammonia Excretion ◽  
Air Exposure ◽  
Urea Excretion ◽  
Experimental Fish ◽  
Urea Content ◽  
Specific Activities ◽  
Oxyeleotris Marmoratus

Ammonia levels in various tissues of the marble goby Oxyeleotris marmoratus remained constant throughout a 72 h period of air exposure. The rate of ammonia excretion in these experimental fish decreased to approximately one-fifth of that of the submerged control. Ammonia was not converted to urea during air exposure because there were no significant increases in urea content in the tissues. Also, urea excretion rate was lowered to one-fiftieth that of the submerged fish. After 24 h of air exposure, there was a significant increase in muscle glutamine content, which peaked at 48 h. The increase in glutamine content could account for the decreases in the amounts of ammonia and urea excretion during air exposure. The specific activities of hepatic glutamate dehydrogenase (amination) and glutamine synthetase in these experimental fish increased threefold and thirtyfold, respectively, in comparison with the submerged controls. Thus, O. marmoratus appears to be the first known teleost that responds to air exposure by activating hepatic glutamine synthetase to detoxify internally produced ammonia.

Urea Excretion Rate as a Contributor to Trimethoprim-induced Hyperkalemia

1994 ◽  
Vol 120 (2) ◽  
pp. 166
Author(s):  
Heino Velazquez
Keyword(s):  
Excretion Rate ◽  
Urea Excretion

The Metabolism of Trichinosed Rats During the Early Phase of the Disease

1941 ◽  
Vol 19 (3-4) ◽  
pp. 87-104 ◽  
Author(s):  
W. P. Rogers
Keyword(s):  
Intestinal Mucosa ◽  
Great Increase ◽  
Trichinella Spiralis ◽  
Excretion Rate ◽  
Mechanical Damage ◽  
Ammonia Excretion ◽  
Protein Digestion ◽  
Crude Fibre ◽  
Urea Excretion ◽  
Time Of Infection

The changes in protein digestion, crude fibre digestion and the chief urinary constituents found in four rats after experimental infection with Trichinella spiralis are detailed.Diarrhoea and anorexia occurred during the period 8 to 12 days after infection when protein digestion fell to its lowest point. It is suggested that this was due to antiproteases secreted by the adult parasites and to mechanical damage in the intestinal mucosa caused by their movements.Urinary N rose immediately after infection in “non-resistant” rats. This was followed by a period of decreased N output after which the excretion rate rose steeply.The urea output also rose immediately after infection in “non-resistant” rats. During the period 4 to 12 days from the time of infection urea excretion fell. Thereafter there was a great increase in its rate of output. Most of these changes have been attributed to toxins elaborated by the adult parasites for massive larval invasion of the tissues probably did not occur till after the experiments were terminated.Ammonia excretion rose as urinary urea decreased. The fall in urea N was not compensated by the rise in ammonia N + the fall in dietary N intake. The ammonia output returned rapidly to normal suggesting that the excess ammonia was not produced in response to acidosis when the urea excretion rate rose.Creatine excretion showed a marked fall during the period 4 to 12 days after infection. Urinary creatine and creatinine rose steeply following this period. Possible reasons for these variations are discussed.

PRODUCTION AND EXCRETION OF UREA BY THE FETAL LAMB

PEDIATRICS ◽  
1972 ◽  
Vol 50 (3) ◽  
pp. 372-379
Author(s):  
Edwin L. Gresham ◽  
Elizabeth J. James ◽  
John R. Raye ◽  
Frederick C. Battaglia ◽  
Edgar L. Makowski ◽  
...  
Keyword(s):  
Production Rate ◽  
Excretion Rate ◽  
Mean Value ◽  
Fetal Weight ◽  
Fetal Life ◽  
Concentration Difference ◽  
Urea Excretion ◽  
Arterial Blood ◽  
Fetal Lamb ◽  
Urea Production

The urea production rate of the fetal lamb has been measured in 10 pregnant ewes studied who were free of operative stress. The measurement of the fetal urea production rate was made by utilizing an independent measurement of placental urea clearance by the infusion of urea tagged with radioactive carbon (14C) into the fetal circulation and the endogenous concentration difference for urea between umbilical arterial blood and maternal arterial blood. It was shown that the concentration difference of urea between umbilical arterial and maternal arterial blood is significantly elevated during the first four days of recovery from surgery, with a mean value of 0.06 mg/ml plasma water on the first day. By the fifth postoperative day this concentration difference has decreased to a mean value of 0.034, which does not change from the fifth to the twelfth postoperative days. This study demonstrates that urea is excreted across the placenta at a rate of approximately 0.54 mg/min/kg fetal weight. By comparison with the urea excretion rate of adult sheep, this is a high rate of fetal urea excretion. It was demonstrated that the urea excretion rate across the placenta could be increased threefold by an infusion of ammonium lactate into the fetus. Thus, the endogenous urea excretion rate of 0.54 mg/min/kg fetal weight does not represent the maximum rate of urea production for the fetus. The finding of a high urea production rate in fetal life is new and contrary to the common belief that nitrogen catabolism plays a minor role in fetal life. These studies demonstrate that as much as 25% of the fetal oxygen consumption could be accounted for by the catabolism of amino acids.

Hypotonic saline infusion alters the renal response to amino acids in men

1999 ◽  
Vol 276 (1) ◽  
pp. F137-F142 ◽  
Author(s):  
Aldo Claris-Appiani ◽  
Amedea S. Tirelli ◽  
Gianluigi Ardissino ◽  
Valeria Daccò ◽  
Eugenia Moretto ◽  
...  
Keyword(s):  
Amino Acids ◽  
Sodium Excretion ◽  
Metabolic Response ◽  
Excretion Rate ◽  
Extracellular Volume ◽  
Urinary Sodium Excretion ◽  
Saline Infusion ◽  
Urea Excretion ◽  
Hypotonic Saline ◽  
Sodium Handling

We investigated the effects of hypotonic saline-induced modifications of extracellular volume and sodium handling on the renal and metabolic response to amino acids (AA). Renal hemodynamics (Inutest, p-aminohippurate clearance), plasma AA, and glucagon levels, as well as urea and sodium excretion, were studied in seven adult volunteers infused for 2 h, on six separate occasions, according to the following protocols: 1) high-AA solution (300 mg ⋅ min−1 ⋅ 1.73 m−2); 2) low-AA solution (150 mg ⋅ min−1 ⋅ 1.73 m−2); 3) low AA + 2,000 ml/1.73 m2 of 0.23% saline solution; 4) high AA + 0.23% saline; 5) high AA + 0.45% saline; and 6) 0.45% saline alone. The glomerular filtration rate (GFR) rise induced by the high-AA solution was similar to that induced by the low-AA solution (ΔGFR = +24 ± 6 and +20.2 ± 7 ml ⋅ min−1 ⋅ 1.73 m−2, respectively), whereas the plasma AA and glucagon levels and urea excretion rate increases were related to AA dose. The addition of 0.23% saline to the low-AA solution and of 0.45% saline to the high-AA solution blunted the renal hemodynamic response (ΔGFR = +6.6 ± 10.1 and +11.4 ± 8.3 ml ⋅ min−1 ⋅ 1.73 m−2, respectively) without modifying the pattern of plasma AA and glucagon levels and urea excretion observed with the AA infusion alone. Urinary sodium excretion increased from baseline with each protocol and rose even further when saline was added to AA. A negative correlation ( r = −0.38, P < 0.05) was found between the changes from basal values in GFR and those in sodium excretion rate with high-AA infusion at different levels of sodium concentration. These data suggest that AA-induced hyperfiltration might be blunted by hypotonic saline infusion, possibly through an acute modification of renal sodium handling and extracellular volume.

Arteriovenous Differences in Concentration of Haemoglobin and Urea Across the Forestomachs of Sheep Given Lucerne Chaff

1971 ◽  
Vol 24 (3) ◽  
pp. 403 ◽  
Author(s):  
JF Hecker ◽  
JV Nolan
Keyword(s):  
Excretion Rate ◽  
Urea Nitrogen ◽  
Urea Excretion ◽  
Rumen Epithelium ◽  
Wide Acceptance

Since the concept of movement of urea nitrogen across the rumen wall was proposed by Simonnet, Le Bars, and Molle (1957), it has gained wide acceptance. Experiments using isolated, washed, saline-filled rumens of anaesthetized sheep (Houpt 1959; Hogan 1961; Ash and Dobson 1963; Packett and Groves 1965) and rumen pouches (Juhasz 1965; Houpt and Houpt 1968) have shown that urea can cross the rumen wall, appearing in the lumen mainly as ammonia. Gray, Pilgrim, and Weller (1958), Harris and Phillipson (1962), and Kay and Phillipson (1962) have shown that, with diets low in protein, more nitrogen may pass from the abomasum than is contained in the feed, indicating entry of endogenous nitrogen to the rumen. As the salivary urea excretion rate may account for only about 0�5 g nitrogen per day (McDonald 1948), it has been implied that the gain in nitrogen results from passage of urea nitrogen through the rumen epithelium from the blood (Houpt 1959; Kay and Hobson 1963; Juhasz 1965; Houpt and Houpt 1968; Tillman and Sidhu 1969).

Daily Pattern of Nitrogen Excretion and Oxygen Consumption of Sockeye Salmon (Oncorhynchus nerka) under Controlled Conditions

1975 ◽  
Vol 32 (12) ◽  
pp. 2479-2486 ◽  
Author(s):  
J. R. Brett ◽  
C. A. Zala
Keyword(s):  
Oxygen Consumption ◽  
Sockeye Salmon ◽  
Excretion Rate ◽  
Oncorhynchus Nerka ◽  
Ammonia Excretion ◽  
Nitrogen Excretion ◽  
Average Weight ◽  
Urea Excretion ◽  
Maintenance Ration ◽  
Exogenous Nitrogen

Measurements of the rate of ammonia and urea excretion of fingerling sockeye salmon (Oncorhynchus nerka) in fresh water were made at 2–3-hourly intervals throughout the day (average weight = 29 g; temperature = 15 C). One group of fish was fed a maintenance ration while another group was starved for 22 days. Ammonia excretion rose to a sharp peak of 35 mg N/kg per hour, 4–41/2 h after the start of feeding (at 0830) and fell to a baseline level of 8.2 mg N/kg per hour between 0200 and 0800. Urea excretion remained relatively steady at a mean rate of 2.2 mg N/kg per hour throughout the day, showing no diurnal response to feeding. Starved fish showed a nitrogen excretion rate close to that for both the steady state of urea excretion and the baseline rate of ammonia excretion of the fed fish. Oxygen consumption rose to a peak of 370 mg O2/kg per hour just before and during a 1-h feeding period, decreasing thereafter to a low of 170 mg O2/kg per hour at 0300 h. For the starved fish this diurnal metabolic fluctuation continued from the start in a variable and diminishing form whereas nitrogen excretion showed no such response. The results are discussed in relation to hatchery observations. We conclude that for nonstressed salmon at 15 C ammonia is the chief excretory product of exogenous nitrogen metabolism.

Osmorégulation et métabolisme de l'urée : comparaison entre Bufo viridis et Rana temporaria

1968 ◽  
Vol 46 (3) ◽  
pp. 295-301 ◽  
Author(s):  
Robert P. Harpur
Keyword(s):  
Weight Loss ◽  
Body Weight ◽  
Large Intestine ◽  
Sea Water ◽  
Rana Temporaria ◽  
Urine Concentration ◽  
Arginase Activity ◽  
Temporary Reduction ◽  
Bufo Viridis ◽  
Urea Excretion

A comparison is made between the euryhaline species Bufo viridis, which can survive in more than 50% sea water, and the stenohaline species Rana temporaria, which cannot. The elevated blood urea, which B. viridis uses for osmoregulation, comes from a temporary reduction in the amount of urea excreted and possibly from an increased urea production. Below 40% seawater B. viridis shows no change in body weight but in 30% seawater there is a marked reduction in urea excretion and an increase in liver arginase activity. High salinity does not increase arginase activity further. The toads do show a weight loss with each increment of salinity above 40% seawater but the daily urea excretion returns towards the level of freshwater controls. In 60% seawater (546 milliosmolal) the bladder urine concentration is 575 ± 51 mosmolal with urea accounting for 107 ± 8 mosmolal and that of the contents of the large intestine is 582 ± 41 mosmolal but with only traces of urea. Nematodes (Aplectana sp.) in the large intestine are unaffected by 60% seawater.On the other hand, R. temporaria shows an increase in body weight when placed in 10% and in 20% seawater. In 30% seawater there is weight loss and increased urea excretion but no increase in liver arginase activity.

Urea Excretion Rate as a Contributor to Trimethoprim-induced Hyperkalemia

1994 ◽  
Vol 120 (2) ◽  
pp. 166 ◽  
Author(s):  
Martin Schreiber
Keyword(s):  
Excretion Rate ◽  
Urea Excretion
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