Ammonium excretion during stopped flow: a hypothetical ammonium countercurrent system

1965 ◽  
Vol 209 (2) ◽  
pp. 273-282 ◽  
Author(s):  
Lawrence P. Sullivan
Keyword(s):  
Venous Blood ◽  
Ammonium Concentration ◽  
Ammonium Excretion ◽  
Urine Ph ◽  
Blood Concentrations ◽  
Occlusion Time ◽  
Alkaline Urine ◽  
Urine Concentrations ◽  
Counter Current ◽  
Current Mechanism

Successive ureteral occlusions were performed on chronically acidotic animals infused first with HCl and then with NaHCO3. Peak ammonium concentrations developed in very distal samples of each occlusion were compared with urine pH. In successive occlusions on any one dog, the line relating peak ammonium concentration to urine pH closely followed the slope predicted by the theory of nonionic diffusion when urine pH was above 6.0. When urine pH was below 6.0 in successive occlusions, the slope was significantly less than the theoretical. In these latter experiments, doubling occlusion time resulted in small increases in ammonium concentration. Glutamine infusions raised ammonium concentrations and tended to shift the slope towards the theoretical at urine pH's down to 5.6. In alkalotic animals, the ratio [NH4]u/ [NH4]b was much greater than predicted by theory, and urine concentrations of the free base NH3 were as much as fourfold greater than renal venous blood concentrations. A counter-current mechanism for ammonium is proposed to explain the ability of the kidney to concentrate NH3 in alkaline urine.

Effect of rapid and transitory changes in blood and urine pH on NH4 excretion

1963 ◽  
Vol 204 (6) ◽  
pp. 1077-1085 ◽  
Author(s):  
Lawrence P. Sullivan ◽  
Michael McVaugh
Keyword(s):  
Venous Blood ◽  
Ammonium Concentration ◽  
Ammonium Excretion ◽  
Urine Ph ◽  
Osmotic Diuresis ◽  
Blood Ph ◽  
The Difference ◽  
In Transit ◽  
Relationship Of ◽  
The Relationship

The Chinard technique of close arterial injection has been adapted to permit a closer study of the relationship of pH to ammonium excretion. NaHCO3, Na4Fe(CN)6, HCl, and creatinine hydrochloride solutions were injected into a renal artery of a dog undergoing osmotic diuresis while 15-sec serial urine and renal venous blood samples were being collected. Because of the difference in transit time between blood and urine the effect of the alteration in blood pH upon ammonium excretion could be seen before the filtered portion of the injection reached the urine. Thus NaHCO3 in the blood raised urine ammonium concentration while urine pH remained relatively constant. Later as NaHCO3 appeared in the urine, pH rose and urine ammonium concentration fell. Na4Fe(CN)6, which decreased blood pH, produced opposite effects. HCl and creatinine hydrochloride caused an immediate fall in both urine pH and ammonium concentration which persisted during the appearance of the injection in the urine. The results of these experiments are interpreted in terms of the theory of nonionic diffusion.

Effect of parathyroid hormone on urinary acidification

1977 ◽  
Vol 232 (5) ◽  
pp. F429-F433 ◽  
Author(s):  
J. A. Arruda ◽  
L. Nascimento ◽  
C. Westenfelder ◽  
N. A. Kurtzman
Keyword(s):  
Parathyroid Hormone ◽  
Renal Tubular Acidosis ◽  
Ammonium Excretion ◽  
Distal Nephron ◽  
Urine Ph ◽  
Alkaline Urine ◽  
Acid Urine ◽  
Urinary Acidification ◽  
Before And After ◽  
Renal Tubular

The effect of parathyroid hormone (PTH) administration on urinary acidification was studied in intact and thyroparathyroidectomized dogs. PTH administration resulted in a significant increase in urine pH and HCO3 excretion. In dogs with maximally acid urine caused by Na2SO4 infusion PTH administration also led to a significant increase in urine pH and to a decrease in ammonium excretion. To examine the effect of PTH on H+ secretion in the distal nephron we measured the urine-blood (U-B) PCO2 gradient in dogs with maximally alkaline urine (urine pH greater than 7.8) before and after PTH administration. After infusion of the hormone, HCO3 excretion increased significantly but the U-B PCO2 gradient remained unchanged. The effects of PTH infusion on urinary acidification in animals with distal renal tubular acidosis caused by LiCl administration were also studied. PTH administration to these dogs increased HCO3 excretion to the same level seen in normal dogs. These data suggest that PTH does not inhibit distal H+ secretion but increases HCO3 excretion by depressing proximal HCO3 reabsorption.

Branched-Chain Amino Acids, Nitrogen Excretion and Injury in Man

1976 ◽  
Vol 50 (5) ◽  
pp. 393-399 ◽  
Author(s):  
J. H. Wedge ◽  
R. De Campos ◽  
A. Kerr ◽  
R. Smith ◽  
Rose Farrell ◽  
...  
Keyword(s):  
Amino Acids ◽  
Venous Blood ◽  
Branched Chain Amino Acids ◽  
Nitrogen Excretion ◽  
Adult Males ◽  
Blood Concentrations ◽  
Branched Chain ◽  
Injured Patients ◽  
Urinary Nitrogen Excretion ◽  
Urinary Nitrogen

1. Venous blood concentrations of the branched-chain amino acids, valine, leucine and isoleucine, and urinary nitrogen excretion have been measured in sixteen adult males, from 2 h to 7 days after injury, and in four adults after elective skin grafts. 2. In the injured group the concentrations of these amino acids rose significantly 24 h after injury and had doubled at 4 days and remained high; in contrast the skin-graft patients showed no significant change. 3. In those injured patients with initial hyperketonaemia, defined as more than 0·2 mmol/l, the increase in concentrations of branched-chain amino acids at the fourth and seventh days after injury was significantly less than in those with normoketonaemia, and was accompanied by lower urinary nitrogen excretion throughout the whole period. 4. It is suggested that the changes in the concentration of branched-chain amino acids after injury indicate decreased uptake by muscle or excessive release due to an imbalance between protein synthesis and protein catabolism in this tissue.

Renal acid excretion in the domestic fowl

1983 ◽  
Vol 104 (1) ◽  
pp. 51-58
Author(s):  
S. Long ◽  
E. Skadhauge
Keyword(s):  
Uric Acid ◽  
Control Diet ◽  
Venous Blood ◽  
Ammonium Phosphate ◽  
Poultry Feed ◽  
Ammonium Excretion ◽  
Acid Excretion ◽  
Total Acid ◽  
Excretion Rates ◽  
Protein Rich

1. In order to assess the role of uricotelism in net renal acid excretion, blood and ureteral urine samples were collected from five hens fed a commercial poultry feed (Diet A) and five hens fed a protein-rich, Na-poor feed (Diet B). All samples were analysed for pH, PCO2, ammonium, phosphate, uric acid and urates (UA + U) and inulin. 2. On Diet A, average pH in venous blood was 7.42, while urinary pH (pHu) ranged from 4.74 to 7.25. At average pHu (6.10), uric acid accounted for 52% of total acid excreted, H2PO4 for 20% and NH4 for 28%. Net acid excretion in ureteral urine was 345 muequiv h-1 kg body weight-1, or 5–10 times that observed in ureotelic vertebrates (amphibians and mammals). 3. The relative contributions of these urinary buffers to net renal acid excretion changed with pHu. Significant negative correlations exist between pHu and both total phosphate and ammonium excretion rates (P less than 0.001). Excretion rates of (UA + U) showed a positive correlation (P less than 0.05) with pHu. 4. Feeding on Diet B revealed the homeostatic power of the avian kidney. Blood pH and PCO2 were not changed relative to values in hens fed the control diet while striking increases in excretion rates of all urinary buffers (except HCO3) were observed. Average pHu fell to 5.12, and the average net renal acid excretion rate doubled.

Pre- and post-sinusoidal origin of hepatic exudate in anesthetized cats

1991 ◽  
Vol 69 (12) ◽  
pp. 1914-1916 ◽  
Author(s):  
C. V. Greenway ◽  
I. R. Innes ◽  
G. D. Scott
Keyword(s):  
Steady State ◽  
Venous Pressure ◽  
Venous Blood ◽  
Portal Blood ◽  
Substantial Part ◽  
Blood Concentrations ◽  
Small Doses ◽  
Hepatic Venous Blood

In cats anesthetized with pentobarbital, hepatic venous pressure was increased to cause drops of exudate to appear on the surface of the liver. These drops were collected during steady-state infusions of small doses of ethanol and galactose when there was a large arteriovenous gradient across the liver. Comparison of the concentrations of these substances in arterial, portal, and hepatic venous blood and exudate showed that the exudate concentrations were slightly higher than the hepatic venous concentrations but markedly lower than arterial and portal blood concentrations. We conclude that the exudate cannot be entirely formed in the space of Mall (presinusoidal) but a substantial part is postsinusoidal in origin. If the exudate is a mixture of fluids equilibrated with inflowing and outflowing blood, then 75–80% of the exudate is postsinusoidal and 20–25% is presinusoidal in origin.Key words: lymph, ascites, galactose, ethanol.

SELECTED PHYSIOLOGICAL EFFECTS RESULTING FROM ADDITION OF SODIUM BICARBONATE TO DIETS FOR YEARLING HORSES

1985 ◽  
Vol 65 (3) ◽  
pp. 745-751
Author(s):  
N. R. DEUEL ◽  
L. M. LAWRENCE ◽  
W. W. ALBERT
Keyword(s):  
Sodium Bicarbonate ◽  
Venous Blood ◽  
Average Daily Gain ◽  
Dry Weight ◽  
Serum Glucose ◽  
Feed Additives ◽  
Urine Ph ◽  
Lower Serum ◽  
Mineral Supplement ◽  
Protein Levels

Sodium bicarbonate or a commercial vitamin-mineral mixture was included at the 1% level (air-dry weight) in the diets of 16 yearling horses over a 140-day period in a 2 × 2 factorial design. Feed additives resulted in a pH range from 5.78 to 7.87 in the concentrate portion of the diets. Feces, urine and venous blood were collected 24 h after feeding the concentrate. Average daily gain, respiration rate, venous pCO2 and pO2, as well as serum K, Cl, Ca, P, urea N and protein levels were unaffected by treatment. Horses receiving the vitamin-mineral supplement had higher serum Na and lower serum glucose concentrations than horses not receiving the supplement. Horses receiving sodium bicarbonate had a higher urine pH, lower fecal pH, higher packed cell volume, lower blood pH and lower serum glucose concentrations at 24 h after a meal than horses not receiving the buffer. Key words: Horse, sodium bicarbonate, dietary supplements, hematology

Urinary prostaglandin F2α excretion is not pH-dependent in the conscious rat: implications for the urinary prostaglandin E2/prostaglandin F2α ratio

1990 ◽  
Vol 78 (2) ◽  
pp. 181-184 ◽  
Author(s):  
J. Haylor ◽  
C. J. Lote
Keyword(s):  
Excretion Rate ◽  
Ph Dependence ◽  
Prostaglandin F2α ◽  
Urine Ph ◽  
Marked Contrast ◽  
Conscious Rat ◽  
Alkaline Urine ◽  
Site Of Action ◽  
Accurate Reflection

1. The influence of urine pH on the urinary excretion of prostaglandin (PG) F2α and the PGE2/PGF2α ratio has been examined in the conscious rat. 2. The basal urinary PGF2α excretion rate of 3.9 pmol/h (n = 23) did not vary with urine pH. In marked contrast, PGE2 excretion increased as the urine became more alkaline. The PGE2/PGF2α ratio therefore progressively increased from 1.5 to 22 as the pH of the urine changed from pH 5.8 to pH 7.8. 3. The independence of PGF2α excretion from urine pH: (a) excludes cyclo-oxygenase as a potential site of action for the pH-dependence of urinary PGE2 excretion; (b) suggests that the urinary PGE2/PGF2α ratio measured in alkaline urine may be a more accurate reflection of the kidneys, ability to synthesize these two prostaglandins in vivo; (c) suggests that control of urine pH is required before the urinary PGE2/PGF2α ratio can be employed as an index of PGE2 9-ketoreductase (EC 1.1.1.189) activity in vivo.

scholarly journals Topsy-turvy: turning the counter-current heat exchange of leatherback turtles upside down

2015 ◽  
Vol 11 (10) ◽  
pp. 20150592 ◽  
Author(s):  
John Davenport ◽  
T. Todd Jones ◽  
Thierry M. Work ◽  
George H. Balazs
Keyword(s):  
Heat Exchangers ◽  
Venous Blood ◽  
Vascular Supply ◽  
The Body ◽  
Leatherback Turtles ◽  
The Core ◽  
Arterial Blood ◽  
Hip Muscles ◽  
Counter Current ◽  
Current Heat

Counter-current heat exchangers associated with appendages of endotherms feature bundles of closely applied arteriovenous vessels. The accepted paradigm is that heat from warm arterial blood travelling into the appendage crosses into cool venous blood returning to the body. High core temperature is maintained, but the appendage functions at low temperature. Leatherback turtles have elevated core temperatures in cold seawater and arteriovenous plexuses at the roots of all four limbs. We demonstrate that plexuses of the hindlimbs are situated wholly within the hip musculature, and that, at the distal ends of the plexuses, most blood vessels supply or drain the hip muscles, with little distal vascular supply to, or drainage from the limb blades. Venous blood entering a plexus will therefore be drained from active locomotory muscles that are overlaid by thick blubber when the adults are foraging in cold temperate waters. Plexuses maintain high limb muscle temperature and avoid excessive loss of heat to the core, the reverse of the accepted paradigm. Plexuses protect the core from overheating generated by muscular thermogenesis during nesting.

Effects of Prolonged Administration of Diamox on Excretion of Acid and Carbonic Anhydrase and Glutaminase Activities in the Kidney

1957 ◽  
Vol 189 (3) ◽  
pp. 551-556 ◽  
Author(s):  
Donald W. Seldin ◽  
Floyd C. Rector ◽  
H. C. Teng
Keyword(s):  
Carbonic Anhydrase ◽  
Enzyme System ◽  
Chronic Administration ◽  
Carbonic Anhydrase Activity ◽  
Prolonged Administration ◽  
Urine Ph ◽  
Alkaline Urine ◽  
Titratable Acid ◽  
Load Effects ◽  
Renal Carbonic Anhydrase

Diamox inhibits renal carbonic anhydrase activity as effectively when given chronically as when given acutely. The persistently high urine ph, low titratable acid and high bicarbonate excretion in the urine of rats receiving Diamox chronically were the result of the alkaline load effects of sodium Diamox, rather than effects from the inhibition of carbonic anhydrase. The chronic administration of Diamox activated the renal glutaminase enzyme system, resulting in the excretion of normal or increased amounts of ammonia into an alkaline urine. The activation of glutaminase was potentiated by the restriction of dietary NaCl. An unexplained hypernatremia developed during the course of prolonged administration of Diamox.

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