Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D05329 (Ringer's solution)
2,826 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Studies were designed to compare the segmental analysis of sodium reabsorption along the nephron during volume expansion with either 10% body weight Ringer's or 0.6% body weight hyperoncotic albumin. Total kidney and nephron glomerular filtration rate increased similarly with both, but urinary sodium excretion (12.7 vs. 4.0 mueq/min, P < 0.001) and fractional sodium excretion (5.0 vs. 1.6%, P < 0.001) increased to a greater extent with Ringer's. Fractional reabsorption of sodium in the proximal tubule was diminished in both groups but to a significantly greater extent during Ringer's (P < 0.005). Absolute reabsorption was inhibited only in the Ringer's group. Delivery of filtrate out of the proximal tubule was greater in the Ringer's studies, 45 vs. 37 nl/min (P < 0.001). However, both fractional and absolute sodium delivery to the early and late distal tubule were not significantly different in the two groups. Fractional reabsorption in the collecting duct decreased from 96% in hydropenia to 31% during Ringer's but fell only slightly to 80% in the albumin studies. Absolute collecting duct reabsorption was also greater in the albumin studies, 0.55 vs. 0.21 neq/min (P < 0.001), which could totally account for the difference in urinary sodium excretion between the two groups. (22)Na recovery in the final urine after end distal microinjections was 71% during Ringer's infusion and 34% during albumin (P < 0.001). From these data we conclude that: (a) Ringer's solution has a greater inhibitory effect on proximal tubular sodium reabsorption, and (b) in spite of this effect, differences in mucosal to serosal collecting duct sodium transport are primarily responsible for the greater natriuresis during Ringer's infusion.
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PMID:A comparison of the segmental analysis of sodium reabsorption during Ringer's and hyperoncotic albumin infusion in the rat. 472 61

A close relationship has been observed between the clearance rates of sodium and calcium under a variety of diuretic conditions. The thiazide diuretics act differently in dissociating the renal tubular reabsorption of sodium and calcium. This phenomenon has been further investigated using recollection micropuncture and clearance techniques in a group of 14 dogs subjected to three consecutive experimental phases: expansion to 3% of body weight (BWt) with Ringer's solution, chlorothiazide infusion at 20 mg/kg/h, and furosemide in a prime of 10 mg/kg/ and a 10 mg/kg/h infusion. Diuretic losses were balanced with infusion of equal volumes of Ringer's solution throughout the experiment. Chlorothiazide increased the fractional excretion (FE) of sodium almost threefold while FE(Ca) was not significantly altered. Furosemide increased FE(Na) and FE(Ca) to an approximately equal, and more marked, degree. This dissociation of sodium and calcium reabsorption after chlorothiazide was also evident in the superficial distal tubule, where (tubule fluid/plasma sodium) (TF/P(Na)) increased from 0.32 to 0.49 (P < 0.01) and TF/(ultrafiltrate)UF(Ca) was unchanged (0.35-0.31). Furosemide markedly reduced the transtubular concentration gradient for both sodium (0.86) and calcium (0.94). TF/P(Inul in) decreased progressively from 3.79 to 2.78 to 2.33 in three phases. In the late proximal tubule, chlorothiazide induced a fall of TF/P(Inul in) from 1.57 to 1.44 (P < 0.01), but the ratio TF/UF(Ca): TF/P(Na) was unchanged. Furosemide had no significant proximal effect. It is concluded that acute administration of chlorothiazide reduces sodium reabsorption in the distal hephron, presumably the cortical diluting segment, without affecting calcium reabsorption.
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PMID:Micropuncture study of diuretic effects on sodium and calcium reabsorption in the dog nephron. 472 40

In a previous study we have found that acetylcholine, a renal vasodilator, inhibits fractional and absolute reabsorption of sodium in the proximal tubule of the dog. To delineate whether this effect on proximal tubular sodium reabsorption was related to alterations in renal hemodynamics or to a direct tubular action of the drug, free-flow micropuncture studies were performed in the dog in which the tubular fluid to plasma inulin ratio and nephron filtration rate were determined before and during the administration of a structurally different renal vasodilator, bradykinin. This agent increased sodium excretion from 12 to 96 muEq/min and decreased total kidney filtration fraction from 0.35 to 0.25. However, sodium reabsorption in the proximal tubule of the superficial nephrons was unchanged during bradykinin administration. Since it has been shown that a decrease in filtration fraction and presumably peritubular capillary protein concentration will decrease proximal tubular sodium reabsorption, studies were performed to determine whether the fall in total kidney filtration fraction seen with both vasodilators is paralleled by a similar change in the circulation of superficial nephrons. The results of these studies indicate that neither agent altered superficial nephron capillary protein concentration, hematocrit, or filtration fraction. In contrast, a decrease in capillary protein concentration, hematocrit, and filtration fraction was consistently demonstrated during the intrarenal infusion of 7.5-15 ml/min of Ringer's solution while an increase in these parameters occurred during the i.v. administration of norepinephrine, 60 mug/min. In the Ringer's infusion studies, both fractional and absolute sodium reabsorption in the proximal tubule were decreased concomitant with the fall in capillary protein concentration and hematocrit. THIS DATA SUGGESTS THAT: (a) the hemodynamic effect of renal vasodilatation is not the same in the circulation of all nephrons; (b) the inhibitory effect of acetylcholine on proximal tubular sodium reabsorption is due to a direct tubular action; (c) a decrease in capillary protein concentration and/or hematocrit does decrease proximal tubular sodium reabsorption; (d) although proximal reabsorption of sodium is unchanged in the superficial nephrons during bradykinin administration, a decrease in reabsorption may be present in deeper nephrons in which filtration fraction is decreased.
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PMID:The effect of bradykinin on proximal tubular sodium reabsorption in the dog: evidence for functional nephron heterogeneity. 503 21

Fractional reabsorption of water, sodium, and potassium at proximal and distal tubular sites within the nephron was studied by recollection-micropuncture experiments on dogs undergoing hypertonic mannitol diuresis. After an initial control hydropenic phase, 16% mannitol in modified Ringer's solution was administered intravenously, resulting in marked increases in fractional excretion of water (28.7%), sodium (12.6%), and potassium (63.9%). Inulin clearance decreased significantly from 35.1 to 25.2 ml/min. Analysis of paired micropuncture data revealed a significant decrease in tubule fluid to plasma (TF:P) inulin ratios in both the proximal tubule (1.63-1.45) and distal tubule (5.38-1.94). There was also a significant decrease in proximal TF:P sodium ratios (0.99-0.93) and potassium ratios (1.05-0.98). Distal TF:P sodium ratios, in contrast, rose significantly (0.38-0.59), while TF:P potassium ratios tended towards unity whether initially greater or less than one. Fractional reabsorption of sodium and water decreased by 5% and 10% respectively in the proximal tubule, but to a lesser extent than the resulting increases in fractional urinary excretion. The nonreabsorbed fraction, however, had increased sharply at the point of distal puncture for water (32%), sodium (26%), and potassium (26%), indicating a large inhibitory effect within the loop of Henle in addition to the smaller proximal effects.
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PMID:Micropuncture study of hypertonic mannitol diuresis in the proximal and distal tubule of the dog kidney. 535 44

The effects of acetazolamide (Diamox), parathyroid hormone (PTH) and dibutyrylcyclic-adenosine 3':5'-monophosphate (db-cAMP) on fluid and 5,5-dimethyl-2,4-oxazolidinedione (DMO) absorption in the rat proximal convoluted tubule were studied by using microperfusion methods. The rate of tubular absorption of DMO was used to estimate the rate of hydrogen ion secretion. When the tubular and the peritubular capillaries were perfused simultaneously with bicarbonate-free Ringer's solution containing DMO, the rate of DMO absorption (JDMO) was 140 +/- 15.7 pmol/min . mm, a value comparable to the rate of absorption of bicarbonate and glycodiazine, and net fluid absorption (JV) was 2.20 +/- 0.19 nl/min . mm. Administration of PTH (10(-6) M) to the capillary perfusate caused a decrease of JDMO by 23% and a decrease of JV by 28%. Similar results were observed when db-cAMP (10(-4) M) was administered to the luminal perfusate. Addition of acetazolamide (10(-4) M) to the luminal perfusate caused a decrease of JDMO by 66% and a decrease of JV by 45%. The effect of either PTH or db-cAMP was additive to the maximal effect of acetazolamide. However, the effect of PTH was not additive to the effect of db-cAMP. Thus, the results suggest that PTH and acetazolamide have different mechanisms of action on fluid and DMO absorption by proximal tubule and that cAMP mediates the effect of PTH.
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PMID:Different mechanisms of action of acetazolamide and parathyroid hormone on proximal tubular absorption of fluid and 5,5-dimethyl-2,4-oxazolidinedione. 625 30

Acidification in proximal tubule of the isolated rat kidney, perfused in vitro, was studied by stopped-flow microperfusion techniques, using Sb microelectrodes to measure luminal pH. The kidney was perfused with mammalian Ringer's solution at pH 7.4 buffered by 20 mmol/l phosphate and containing 7.5 g/100 ml bovine albumin, equilibrated with air. Final urine pH was 6.88 +/- 0.5. Steady-state pH in proximal segments was 6.81 +/- 0.03 (n = 80), and acidification half-time (t/2) 7.25 +/- 0.33 (80) s, giving a net secretory H+ ion flux of 0.51 +/- 0.05 nmol . cm-2 . s-1. This flux was about 70% of "in vivo" (blood perfused kidneys). During luminal perfusion with solutions at pH 6.2, back-flux of H+ was 0.82 +/- 0.08 nmol . cm-2 . s-1, with an alkalinization t/2 of 6.33 +/- 0.34 (34) s. The difference between acidification and alkalization t/2 was not significant. This is compatible with a pump-leak system of H+ transport. This is compatible with a pump-leak system of H+ transport. The back flux of H from the lumen was markedly reduced in low Na+ perfused kidneys in the presence of 10(-4) mol/l amiloride in the lumen, indicating that this process is mediated by the luminal Na/H exchanger. Observations in the presence of high K levels suggest that it may have also a charged component. 10(-4) mol/l acetazolamide added to the kidney perfusate reduced acidification to 0.5% of control, and 10(-6) mol/l SITS to 25% of control. Thus, despite the low pCO2 (0.1-0.4 kPa, or 1-3 mm Hg), the CO2/HCO-3 buffer system still plays an important role in tubular acidification in this preparation.
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PMID:H+ ion secretion in proximal tubule of low-Co2/HCO-3 perfused isolated rat kidney. 680 71

Proximal tubular segments (S1, S2 and S3) of the rabbit kidney were incubated in oxygenated Ringer's solution (30 min, pH 7.4, 37 degrees C) containing bovine serum albumin (10 g/l) and [3H]morphine (0.7 microM). The uptake, expressed as tissue water/medium ratio at equilibrium, for S1 was 42.2 +/- 3.95 (mean +/- S.E.), n = 16 tubules from six animals; for S2, 41.6 +/- 4.17, n = 18 tubules from six animals; and for S3, 29.0 +/- 3.83, n = 15 tubules from six animals, a value significantly lower (P less than .05) than in the S1 and S2 segment. High-performance liquid chromatography analysis of the accumulated tritium revealed metabolism of [3H]morphine. Unchanged morphine represented 35.5 +/- 3.4% of the total radioactivity recovered in the extract from S1 segments, 51.1 +/- 7.7% from S2 and 77.3 +/- 1.8 from S3 segments. After treating the tubular extracts with beta-glucuronidase (5 hr, 25 degrees C), all the recovered radioactivity represented unchanged morphine. The main metabolite, thus, was a glucuronide. KCN (10(-2) M), mepiperphenidol (Darstine, 10(-4) M) and quinine (10(-4) M) inhibited [3H]morphine uptake by 55-70%. Surprisingly, there was no decrease in uptake in the presence of N1-methylnicotinamide (10(-3) M). We conclude that the whole proximal tubule is able to accumulate morphine by a specific transport system for organic cations, but that part of this uptake might be due to cellular metabolism and intracellular binding of the drug.
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PMID:Transport and metabolism of [3H]morphine in isolated, nonperfused proximal tubular segments of the rabbit kidney. 714 42

The properties of the Na-K pump were studied by electrophysiological techniques in the proximal tubule of Necturus kidney. Peritubular capillaries were perfused for a short time with different artificial solutions, then ouabain (50 microM-1 mM) was added to each perfusate and its effects on cell membrane potential were assessed. Addition of ouabain, 1 mM, in a physiologic Ringer's solution (K concentration = 3 mM) failed to produce immediate depolarization. The introduction of the cardiac glycoside (50 microM) in solutions in which external K+ concentration was lowered to 0.75 or 0.3 mM resulted in depolarization by 4.1 +/- 0.8 and 9.5 +/- 1.4 mV, respectively. Furthermore, ouabain brought about an increase of membrane input resistance when added in a solution of lowered K+ concentration, but not in the presence of physiologic K+ concentrations. Readmission of K+ into a K-free perfusate flowing through the renal capillaries for more than 15 min resulted in hyperpolarization, 7.2 + 2.0 mV. These and other observations suggest that the Na-K pump operates in electrogenic fashion when external K+ concentration is lowered. Yet, part of the depolarizing response to ouabain under these conditions is mediated via ouabain-elicited changes of cell membrane permeabilities. The stoichiometry of the Na-K pump at physiologic external K concentrations cannot be assessed from the present experiments.
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PMID:Effects of ouabain on the electrophysiological properties of proximal tubular cells. 714 44

Stable electrical potential differences can be measured by means of conventional glass microelectrodes across the cell membrane of renal tubule cells and across the epithelial wall of single tubules in the doubly perfused kidney of Necturus. These measurements have been carried out with amphibian Ringer's solution, and with solutions of altered ionic composition. The proximal tubule cell has been found to be electrically asymmetrical inasmuch as a smaller potential difference is maintained across the luminal cell membrane than across the peritubular cell boundary. The tubule lumen is always electrically negative with respect to the peritubular extracellular medium. Observations on the effectiveness of potassium ions in depolarizing single tubule cells indicate that the transmembrane potential is essentially an inverse function of the logarithm of the external potassium concentration. The behavior of the peritubular transmembrane potential resembles more closely an ideal potassium electrode than that of the luminal transmembrane potential. From these results, and the effects of various ionic substitutions on the electrical profile of the renal tubular epithelium, a thesis concerning the origin of the observed potential differences is presented. A sodium extrusion mechanism is considered to be located at the peritubular cell boundary, and reasons are given for the hypothesis that the electrical asymmetry across the proximal renal tubule cell could arise as a consequence of differences in the relative sodium and potassium permeability at the luminal and peritubular cell boundaries.
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PMID:Measurements of electrical potential differences on single nephrons of the perfused Necturus kidney. 1370 46

The aim of this study was to determine the effects of fluid resuscitation of acute hemorrhage on the early function and histopathology of the remnant kidney in uninephrectomized rabbits. Thirty-nine adult rabbits were studied in four groups. Group 1 (n = 8) included healthy controls; Group 2 (n = 10) healthy, bled animals; Group 3 (n = 10) uninephrectomized, non-bled animals; and Group 4 (n = 11) uninephrectomized, bled animals. In the hemorrhage groups, 8 mL kg(-1) of blood was drawn, and replaced with lactated Ringer's solution three times the volume of shed blood. Urine and blood samples were collected after 120-minutes of observation. None of the animals experienced hypotension during the study period. Serum and urinary electrolytes were similar between the Groups (p > 0.05). Urine output was lower in Groups 3 and 4 than in Group 1 (p = 0.001, both). Urinary microalbumin, NAG, fractional sodium excretion and creatinine clearance were similar in all four Groups. Light microscopic evaluation revealed only slight enlargement of the proximal tubule lumen in the renal medulla of the rabbits that were both uninephrectomized and bled. We observed no deleterious effects of well resuscitated hemorrhage on early function and histopathology of the remnant kidney in uninephrectomized rabbits.
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PMID:Fluid resuscitation of acute hemorrhage in uninephrectomized rabbits--effects on the early function of the remnant kidney. 1863 Jul 73


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