Effects of Pent-4-Enoic Acid on Renal Free Water, Bicarbonate and Phosphate Excretion in the Dog

1975 ◽  
Vol 49 (5) ◽  
pp. 409-417 ◽  
Author(s):  
J. G. Kleinman ◽  
M. L. Levin
Keyword(s):  
Free Water ◽  
Tubular Reabsorption ◽  
Enoic Acid ◽  
Acid Oxidation ◽  
Water Diuresis ◽  
Water Excretion ◽  
Phosphate Excretion ◽  
Proximal Tubular ◽  
Filtered Load ◽  
Proximal Tubular Reabsorption

1. The effects of pent-4-enoic acid, an inhibitor of fatty acid oxidation, were studied in dogs undergoing water diuresis and acetazolamide diuresis. Free water excretion and distal solute delivery were increased when infusion of pent-4-enoic acid was superimposed on an increasing mannitol diuresis. 2. Bicarbonate excretion increased significantly when infusion of pent-4-enoic acid was superimposed on maximum acetazolamide diuresis. 3. Phosphate excretion exceeded 90% of filtered load when pent-4-enoic acid was administered under stable free water conditions and increased significantly when pent-4-enoic acid was superimposed on stable acetazolamide diuresis. 4. The results are interpreted as indicating inhibition of proximal tubular reabsorption by pent-4-enoic acid, emphasizing the importance of fatty acids as a major fuel for proximal tubular metabolism.

Tubular handling of fluid and electrolytes during ovine pregnancy

1993 ◽  
Vol 265 (2) ◽  
pp. F278-F284 ◽  
Author(s):  
S. C. Cha ◽  
G. W. Aberdeen ◽  
S. Mukaddam-Daher ◽  
E. W. Quillen ◽  
B. S. Nuwayhid
Keyword(s):  
Isotonic Saline ◽  
Free Water ◽  
Tubular Reabsorption ◽  
Distal Nephron ◽  
Free Water Clearance ◽  
Sodium Accumulation ◽  
Saline Loading ◽  
Pregnant Sheep ◽  
Proximal Tubular ◽  
Proximal Tubular Reabsorption

Pregnancy is characterized by progressive water and sodium accumulation and increases in renal blood flow (RBF) and glomerular filtration rate (GFR). However, the influence of the different nephron segments on the increased tubular reabsorption is controversial. Consequently, four nonpregnant and five pregnant sheep were studied, after chronic instrumentation, to assess salt and water reabsorption in the proximal and distal tubules under basal and volume-loaded conditions. Lithium clearance was used as a marker for proximal tubular reabsorption. Volume loading was achieved by the rapid administration of 1,000 ml isotonic saline followed by 250 ml/h for 2 h. Under basal conditions with reference to the nonpregnant state, pregnant sheep had higher (P < 0.05) levels of right RBF (427 +/- 34 vs. 313 +/- 8 ml/min), GFR (133 +/- 7 vs. 94 +/- 9 ml/min), proximal tubular reabsorption (102 +/- 7 vs. 73 +/- 6 ml/min), distal nephron fluid delivery (31 +/- 2 vs. 20 +/- 2 ml/min), and fractional distal nephron reabsorption of fluid (92 +/- 2 vs. 87 +/- 1%) and sodium (98.8 +/- 0.3 vs. 97.0 +/- 0.7%). However, pregnant animals had significantly (P < 0.05) reduced fractional excretions of fluid (1.6 +/- 0.3 vs. 2.6 +/- 0.2%) and sodium (0.24 +/- 0.06 vs. 0.63 +/- 0.19%), but similar levels of filtration fraction, fractional proximal tubular reabsorption, urine flow, urinary sodium excretion, and osmolar and free water clearance. After saline loading, pregnant sheep excreted significantly (P < 0.05) less sodium (9.2 vs. 28.6%) and water (39.8 vs. 56.5%). Decreases in fractional proximal and distal nephron reabsorption of sodium and water after saline loading were attenuated in pregnant animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of acute unilateral renal denervation on tubular sodium reabsorption in the dog

1977 ◽  
Vol 232 (1) ◽  
pp. F16-F19
Author(s):  
G. Nomura ◽  
T. Takabatake ◽  
S. Arai ◽  
D. Uno ◽  
M. Shimao ◽  
...  
Keyword(s):  
Renal Denervation ◽  
Renal Plasma Flow ◽  
Free Water ◽  
Sodium Reabsorption ◽  
Distal Nephron ◽  
Water Diuresis ◽  
Free Water Clearance ◽  
Water Excretion ◽  
Tubular Sodium Reabsorption ◽  
Renal Tubular

The effects of acute denervation of the kidney on renal tubular sodium and water excretion were studied in anesthetized, hypophysectomized, and cortisone-treated mongrel dogs during stable water diuresis produced by the infusion of 2.5% dextrose. In all experiments, denervation natriuresis, and diuresis were observed without significant change in glomerular filtration rate (GRF) and renal plasma flow (RPF). Fractional sodium delivery to the distal nephron (CNa + CH2O/100 ml GFR) and fractional free water clearance (CH23/100 ml GFR) was significantly greater in the denervated kidney compared with the innervated kidney (9.6+/-1.2 vs. 6.7+/-0.9% and 8.8+/-1.2 vs. 6.5+/-0.8%, respectively). Distal tubular sodium reabsorption (CH2O/(CNa + CH2O)) was not significantly different. We conclude that renal denervation primarily affects the proximal tubule as manifested by a decrease in the reabsorption of sodium and water. A small effect of denervation on the distal nephron is not completely ruled out.

Intrarenal Control of Proximal Tubular Reabsorption of Sodium and Water

Nephron ◽  
1969 ◽  
Vol 6 (3) ◽  
pp. 247-259 ◽  
Author(s):  
E.E. Windhager ◽  
J.E. Lewy ◽  
A. Spitzer
Keyword(s):  
Tubular Reabsorption ◽  
Proximal Tubular ◽  
Proximal Tubular Reabsorption

Posttranscriptional regulation of the proximal tubule NaPi-II transporter in response to PTH and dietary Pi

1999 ◽  
Vol 277 (5) ◽  
pp. F676-F684 ◽  
Author(s):  
Heini Murer ◽  
Ian Forster ◽  
Nati Hernando ◽  
Georg Lambert ◽  
Martin Traebert ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Proximal Tubule ◽  
Posttranscriptional Regulation ◽  
Apical Membrane ◽  
Tubular Reabsorption ◽  
Transport Capacity ◽  
Phosphate Intake ◽  
Proximal Tubular ◽  
Dietary Phosphate ◽  
Proximal Tubular Reabsorption

The rate of proximal tubular reabsorption of phosphate (Pi) is a major determinant of Pi homeostasis. Deviations of the extracellular concentration of Piare corrected by many factors that control the activity of Na-Pi cotransport across the apical membrane. In this review, we describe the regulation of proximal tubule Pi reabsorption via one particular Na-Pi cotransporter (the type IIa cotransporter) by parathyroid hormone (PTH) and dietary phosphate intake. Available data indicate that both factors determine the net amount of type IIa protein residing in the apical membrane. The resulting change in transport capacity is a function of both the rate of cotransporter insertion and internalization. The latter process is most likely regulated by PTH and dietary Pi and is considered irreversible since internalized type IIa Na-Picotransporters are subsequently routed to the lysosomes for degradation.

Flash photolysis of caged nitric oxide inhibits proximal tubular fluid reabsorption in free-flow nephron

2005 ◽  
Vol 289 (2) ◽  
pp. R620-R626 ◽  
Author(s):  
Kay-Pong Yip
Keyword(s):  
Nitric Oxide ◽  
Proximal Tubule ◽  
Flash Photolysis ◽  
Tubular Reabsorption ◽  
Fluid Reabsorption ◽  
Proximal Tubular ◽  
Tubular Flow ◽  
Tubular Fluid Reabsorption ◽  
Reabsorption Rate ◽  
Proximal Tubular Reabsorption

A nonobstructing optical method was developed to measure proximal tubular fluid reabsorption in rat nephron at 0.25 Hz. The effects of uncaging luminal nitric oxide (NO) on proximal tubular reabsorption were investigated with this method. Proximal fluid reabsorption rate was calculated as the difference of tubular flow measured simultaneously at two locations (0.8–1.8 mm apart) along a convoluted proximal tubule. Tubular flow was estimated on the basis of the propagating velocity of fluorescent dextran pulses in the lumen. Changes in local tubular flow induced by intratubular perfusion were detected simultaneously along the proximal tubule, indicating that local tubular flow can be monitored in multiple sites along a tubule. The estimated tubular reabsorption rate was 5.52 ± 0.38 nl·min−1·mm−1 ( n = 20). Flash photolysis of luminal caged NO (potassium nitrosylpentachlororuthenate) was induced with a 30-Hz UV nitrogen-pulsed laser. Release of NO from caged NO into the proximal tubule was confirmed by monitoring intracellular NO concentration using a cell-permeant NO-sensitive fluorescent dye (DAF-FM). Emission of DAF-FM was proportional to the number of laser pulses used for uncaging. Photolysis of luminal caged NO induced a dose-dependent inhibition of proximal tubular reabsorption without activating tubuloglomerular feedback, whereas uncaging of intracellular cGMP in the proximal tubule decreased tubular flow. Coupling of this novel method to measure reabsorption with photolysis of caged signaling molecules provides a new paradigm to study tubular reabsorption with ambient tubular flow.

Sign in / Sign up

Export Citation Format

Share Document