Photochemistry of Colloidal Semiconductors 10. Exclusion Chromatography and Stop Flow Experiments on the Formation of Extremely Small CdS Particles

1986 ◽  
Vol 90 (1) ◽  
pp. 46-49 ◽  
Author(s):  
CH.-H. Fischer ◽  
H. Weller ◽  
A. Fojtik ◽  
C. Lume-Pereira ◽  
E. Janata ◽  
...  
Keyword(s):  
Exclusion Chromatography ◽  
Colloidal Semiconductors ◽  
Flow Experiments ◽  
Stop Flow

TRANSPORT OF ALDOSTERONE AND OF THE ACID LABILE CONJUGATE OF ALDOSTERONE BY TUBULAR CELLS OF THE KIDNEY

1967 ◽  
Vol 55 (4) ◽  
pp. 648-655 ◽  
Author(s):  
K. A. Deck ◽  
W. E. Siegenthaler
Keyword(s):  
Urine Samples ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Flow Experiments ◽  
Stop Flow ◽  
Acid Labile

ABSTRACT Stop flow experiments on dogs receiving continuous infusions of radioactive aldosterone were carried out in order to determine the tubular sites of reabsorption of aldosterone and the tubular sites of secretion of its metabolites. Sodium, p-aminohippuric acid, creatinine, inulin, radioactive aldosterone, radioactive tetrahydroaldosterone and the acid-labile (hydrolyzable) conjugate of aldosterone were analyzed in the urine samples collected after the stop periods. The results of the experiments indicate that aldosterone is mainly reabsorbed at a distal tubular site, that the acid-labile conjugate is secreted mainly at a proximal tubular site, and that tetrahydroaldosterone glucuronide is neither secreted nor reabsorbed by tubular cells. Predominant distal reabsorption of aldosterone is suggested as being a possible reason for the predominant distal sodium-retaining effect of this hormone.

Impaired diluting capacity of the thick ascending limb during loop bicarbonate and nitrate perfusion in vivo

1984 ◽  
Vol 62 (11) ◽  
pp. 1416-1422 ◽  
Author(s):  
Hans-Ulrich Gutsche ◽  
Linda N. Peterson ◽  
Karl-Heinz Sauerwald ◽  
David Z. Levine
Keyword(s):  
Animal Studies ◽  
Urine Concentration ◽  
Thick Ascending Limb ◽  
Distal Nephron ◽  
Nacl Transport ◽  
Minimum Concentration ◽  
Bicarbonate Solutions ◽  
Flow Experiments ◽  
Stop Flow

Previous whole animal studies have indicated that when nitrate or bicarbonate is substituted for chloride, renal concentrating defects can be demonstrated. It has been proposed that function of the "distal nephron" or thick ascending limb may be impaired when chloride is replaced by other anions. To examine this proposal, microstop-flow experiments were performed in rats in which loops were perfused with solutions containing 110 mM NaCl, NaHCO3, or NaNO3. Solute reabsorption by the thick ascending limb was assessed by measuring the minimum conductivity of fluid emerging from the loop following intervals of stop-flow. Thick ascending limb solute transport was impaired in loops perfused with HCO3 or NO3 evidenced by the marked increase in solute remaining in the loop after 60 s of stop-flow. The calculated corresponding sodium concentrations were in the range of 17–24 mM Na for the NaCl perfusion, 57–88 mM Na for the NaHCO3 perfusion, and 57–69 mM Na for the NaNO3 perfusion. Clearly, the minimum concentration achieved with NaCl was approximately one-third of that reached with the nitrate or bicarbonate solutions. These results indicate that when chloride-poor solutions reach the thick ascending limb, an important impairment of diluting capacity is demonstrable in vivo in the rat. The present studies, therefore, provide an important link between recent information regarding the mechanism of NaCl transport in the thick ascending limb and older whole animal studies suggesting an important role for distal chloride delivery in urine concentration.

Effect of metabolic inhibitors on urine osmolality and electrolyte excretion

1963 ◽  
Vol 204 (6) ◽  
pp. 1065-1070 ◽  
Author(s):  
Wolfgang Herms ◽  
Richard L. Malvin
Keyword(s):  
Renal Artery ◽  
Distal Tubule ◽  
Urine Osmolality ◽  
Metabolic Inhibitors ◽  
Before And After ◽  
K Secretion ◽  
Flow Experiments ◽  
K Transport ◽  
Stop Flow

The in vivo effects of aerobic and anaerobic metabolic inhibitors on renal Na and K transport and concentrating ability were studied in dogs. Two aerobic inhibitors (sodium cyanide and hydroxylamine) and two anaerobic inhibitors (iodoacetate and triethyleneiminotriazine) were infused into one renal artery. Urine was collected separately from both kidneys and urine osmolality, Na, and K concentrations were measured. In addition, stop-flow experiments were done before and after infusion of NaCN and iodoacetate into one renal artery. Aerobic inhibitors resulted in a decrease in urine osmolality associated with a large increase in Na excretion. Anaerobic inhibitors resulted in a similar decrease in urine osmolality with only a minimal increase in Na excretion. In stop-flow experiments cyanide blocked Na and K transport in the distal tubule. Iodoacetate had no demonstrable effect on distal Na or K transport, but did abolish K secretion which was presumed to take place in the collecting ducts. These results suggest that Na and K transport in medullary regions is largely dependent on energy derived from anaerobic glycolysis.

Stop-flow localization of renal tubular excretion of tetraethylammonium

1960 ◽  
Vol 198 (6) ◽  
pp. 1267-1270 ◽  
Author(s):  
Barbara R. Rennick ◽  
Gordon K. Moe
Keyword(s):  
Flow Localization ◽  
Low Concentration ◽  
Renal Tubular ◽  
Flow Experiments ◽  
Stop Flow ◽  
Ureteral Occlusion

In stop-flow experiments TEA appeared at about the same proximal level of the tubule as PAH following intravenous or intra-arterial injection during ureteral occlusion. Increasing the duration of occlusion following injection lead to a progressively more distal appearance of TEA and PAH. This movement could be a result of pulsation of the column of fluid in the lumen with resultant slurring of the concentration borders; or of diffusion of intraluminal TEA and PAH from the area of secretion to neighboring low concentration sites; or of distal reabsorption of water with consequent movement of the column.

Site of formation of kinins in the dog nephron

1978 ◽  
Vol 234 (1) ◽  
pp. F36-F40 ◽  
Author(s):  
A. G. Scicli ◽  
R. Gandolfi ◽  
O. A. Carretero
Keyword(s):  
Distal Part ◽  
Sodium Concentration ◽  
Renal Papilla ◽  
Distal Nephron ◽  
Water Reabsorption ◽  
Sodium Potassium ◽  
Kallikrein Activity ◽  
Flow Experiments ◽  
Stop Flow ◽  
Second Peak

The site of formation of kinins in the nephron was determined by stop-flow studies in dogs. Klinin, inulin, sodium, potassium concentrations were measured in the fractions collected during the stop-flow procedures. In addition, in three of the 17 stop-flow experiments, kallikrein activity was also measured. The highest kinin concentration after correction for water reabsorption was found in the fractions that were probably trapped in the distal part of the nephron. Either one or two peak was located either in the fraction overlapping (in one instance) or in the fractions coming prior to the fractions with the highest concentration of potassium. This first peak was present in all but one of the stop-flow experiments and was greater than the second peak. The second peak of kinins was found in 13 of the 17 stop-flow exeriments and was located in the fractions with the lowest sodium concentration. Those fractions with the lowest sodium concentration. Those fractions with the lowest sodium concentration also had the highest kallikrein concentration. No evidence of kinin formation was found in the fractions representing the proximal nephron. We conclude, therefore, that kinins are formed in the distal part of the nephron, with the highest concentration found in the last part of the distal nephron and/or in the renal papilla and pelvis.

Distal site of action of parathyroid hormone on phosphate reabsorption

1975 ◽  
Vol 229 (6) ◽  
pp. 1556-1560 ◽  
Author(s):  
FG Knox ◽  
C Lechene
Keyword(s):  
Parathyroid Hormone ◽  
Proximal Tubule ◽  
Phosphate Transport ◽  
Distal Nephron ◽  
Phosphate Reabsorption ◽  
Site Of Action ◽  
Flow Experiments ◽  
Filtered Load ◽  
Stop Flow ◽  
Distal Site

The sites of inhibited phosphate transport following administration of bovine parathyroid hormone (bPTH) to thyroparathyroidectomized (TPTX) dogs were investigated. Phosphate reabsorption by the proximal and distal nephron was studied using recollection micropuncture, stop-flow methodology, and electron-probe microanalysis. Following bPTH, delivery of phosphate from the proximal tubule increased from 26 to 37% of the filtered load, P less than .01. Fractional phosphate excretion increased from 2.3 +/- 1.5 to 21.4 +/- 2.3%, P less than .001. The increased delivery of phosphate at the point of micropuncture in the proximal tubule accounted for approximately half of the phosphaturia. In six TPTX dogs, which were saline loaded, similiar increases in phosphate delivery from the proximal tubule from 27 +/- 1 to 36 +/- 2% of the filtered load resulted in a strikingly smaller phosphaturia, 5.1 +/- 1 to 9.8 +/- 2.4%, NS. In stop-flow experiments, phosphate concentratin ratios were slightly increased in the proximal nephron and markedly increased in the distal nephron following bPTH. It is concluded that parathyroid hormone markedly decreases phosphate transport in the distal nephron.

Measuring rates of O2 uptake in periportal and pericentral regions of liver lobule: stop-flow experiments with perfused liver

1983 ◽  
Vol 244 (6) ◽  
pp. G656-G659 ◽  
Author(s):  
T. Matsumura ◽  
R. G. Thurman
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Electrode ◽  
Similar Data ◽  
Perfused Rat Liver ◽  
O2 Uptake ◽  
Liver Lobule ◽  
First Time ◽  
Flow Experiments ◽  
Stop Flow ◽  
Fasted Rats

Rates of oxygen uptake in periportal and pericentral regions of the hemoglobin-free perfused rat liver were measured successfully for the first time with a miniature oxygen electrode (tip diameter, 50–60 microns) by stopping the flow of perfusate and measuring the rate of decrease of oxygen concentration on the surface of the liver. Rates of oxygen uptake in periportal and pericentral areas were 131 +/- 9 (mean +/- SD) and 56 +/- 14 mumol X g-1 X h-1 in livers from fed, phenobarbital-treated rats, respectively. In livers from fasted rats, rates of O2 uptake of 141 +/- 12 and 89 +/- 11 mumol X g-1 X h-1 were observed in periportal and pericentral regions, respectively. Similar data were obtained in livers from normal rats. Thus, periportal hepatocytes have higher rates of oxygen uptake than pericentral cells in both the fed and fasted states. Rates of oxygen uptake were not affected in periportal regions by fasting. In contrast, rates of oxygen uptake by hepatocytes in pericentral areas were significantly (P less than 0.001) greater in livers from fasted than from fed rats. This significant increase in oxygen uptake in pericentral hepatocytes as a result of fasting is consistent with the hypothesis that glycolysis occurs predominantly in pericentral regions of the liver lobule.

Stop-flow studies on renal handling of lithium ions in the dog

1962 ◽  
Vol 203 (5) ◽  
pp. 897-900 ◽  
Author(s):  
Louis D. Homer ◽  
Sidney Solomon
Keyword(s):  
Distal Portion ◽  
Lithium Ions ◽  
Renal Handling ◽  
Intravenous Infusions ◽  
K Secretion ◽  
Flow Experiments ◽  
Stop Flow ◽  
Sodium And Potassium ◽  
Stimulation Of

Stop-flow experiments were performed on dogs after serum Li concentrations had been raised to 10–21 mEq/liter with intravenous infusions of Li salts. Li is actively reabsorbed at a distal portion of the nephron close to the site of sodium and potassium reabsorption. Li may cause alkalinization of the urine by inhibiting H+ secretion. Stimulation of K secretion by Li could not be demonstrated. Li may reduce K reabsorption.

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