Adrenergic control of bicarbonate absorption in the proximal convoluted tubule of the rat kidney

1980 ◽  
Vol 388 (2) ◽  
pp. 159-164 ◽  
Author(s):  
Y. L. Chan
Keyword(s):  
Rat Kidney ◽  
Proximal Convoluted Tubule ◽  
Adrenergic Control

Dependence of ion fluxes on fluid transport by rat proximal tubule

1986 ◽  
Vol 250 (4) ◽  
pp. F680-F689 ◽  
Author(s):  
K. Bomsztyk ◽  
F. S. Wright
Keyword(s):  
Proximal Tubule ◽  
Fluid Transport ◽  
Rat Kidney ◽  
Water Flux ◽  
Fluid Secretion ◽  
Proximal Convoluted Tubule ◽  
Ion Fluxes ◽  
Fluid Absorption ◽  
Fluid Flux ◽  
K Transport

The effects of changes in transepithelial water flux (Jv) on sodium, chloride, calcium, and potassium transport by the proximal convoluted tubule were examined by applying a microperfusion technique to surface segments in kidneys of anesthetized rats. Perfusion solutions were prepared with ion concentrations similar to those in fluid normally present in the later parts of the proximal tubule. Osmolality of the perfusate was adjusted with mannitol. With no mannitol in the perfusates, net fluid absorption was observed. Addition of increasing amounts of mannitol first reduced Jv to zero and then reversed net fluid flux. At the maximal rates of fluid absorption, net absorption of Na, Cl, Ca, and K was observed. When Jv was reduced to zero, Na, Cl, and Ca absorption were reduced and K entered the lumen. Na, Cl, and Ca secretion occurred in association with the highest rates of net fluid secretion. The lumen-positive transepithelial potential progressively increased as the net fluid flux was reduced to zero and then reversed. The results demonstrate that changes in net water flux can affect Na, Cl, Ca, and K transport by the proximal convoluted tubule of the rat kidney. These changes in net ion fluxes are not entirely accounted for by changes in bulk-phase transepithelial electrochemical gradients.

scholarly journals Proteomic profiling and pathway analysis of the response of rat renal proximal convoluted tubules to metabolic acidosis

2013 ◽  
Vol 305 (5) ◽  
pp. F628-F640 ◽  
Author(s):  
Kevin L. Schauer ◽  
Dana M. Freund ◽  
Jessica E. Prenni ◽  
Norman P. Curthoys
Keyword(s):  
Metabolic Acidosis ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Pathological Condition ◽  
Rat Kidney ◽  
Proximal Convoluted Tubule ◽  
Kidney Cortex ◽  
Combined Processes ◽  
Proteomic Profiling ◽  
Rat Kidney Cortex ◽  
Cytosolic Proteins

Metabolic acidosis is a relatively common pathological condition that is defined as a decrease in blood pH and bicarbonate concentration. The renal proximal convoluted tubule responds to this condition by increasing the extraction of plasma glutamine and activating ammoniagenesis and gluconeogenesis. The combined processes increase the excretion of acid and produce bicarbonate ions that are added to the blood to partially restore acid-base homeostasis. Only a few cytosolic proteins, such as phosphoenolpyruvate carboxykinase, have been determined to play a role in the renal response to metabolic acidosis. Therefore, further analysis was performed to better characterize the response of the cytosolic proteome. Proximal convoluted tubule cells were isolated from rat kidney cortex at various times after onset of acidosis and fractionated to separate the soluble cytosolic proteins from the remainder of the cellular components. The cytosolic proteins were analyzed using two-dimensional liquid chromatography and tandem mass spectrometry (MS/MS). Spectral counting along with average MS/MS total ion current were used to quantify temporal changes in relative protein abundance. In all, 461 proteins were confidently identified, of which 24 exhibited statistically significant changes in abundance. To validate these techniques, several of the observed abundance changes were confirmed by Western blotting. Data from the cytosolic fractions were then combined with previous proteomic data, and pathway analyses were performed to identify the primary pathways that are activated or inhibited in the proximal convoluted tubule during the onset of metabolic acidosis.

scholarly journals Quantitative immunohistochemical evaluation by image analysis of metallothionein in copper-loaded rat kidney.

1993 ◽  
Vol 41 (5) ◽  
pp. 727-731 ◽  
Author(s):  
K W Schmid ◽  
J M Morgan ◽  
D Ofner ◽  
A Hittmair ◽  
S Haywood ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Image Analysis ◽  
Rat Kidney ◽  
Staining Intensity ◽  
Proximal Convoluted Tubule ◽  
High Copper

Kidneys of copper-loaded rats were investigated immunohistochemically with a directly peroxidase-conjugated monoclonal antibody against metallothionein (MT). By means of an image analyzing system the area and the staining intensity of MT immunoreactivity in the proximal convoluted tubule (PCT) cells were determined. In the present study we compared the data obtained by image analysis with analytically determined tissue copper and MT concentrations of rats fed a high-copper diet (1 g/kg) for 16 weeks and sacrificed sequentially during this period. Our results provide evidence that the area of MT immunoreactivity correlates significantly with tissue copper and MT concentrations. Both the copper and MT concentrations in kidney rose to a maximum at 8 weeks and remained constant thereafter. The observed rise in the staining intensity of MT in PCT cells to a maximum at 6 weeks, which subsequently declined, suggests a continuing redistribution of copper and MT in the kidneys even after a maximum of concentration copper and MT is reached in the tissue.

Effects of intraluminal D-glucose and probenecid on urate absorption in the rat proximal tubule

1979 ◽  
Vol 236 (6) ◽  
pp. F526-F529 ◽  
Author(s):  
T. F. Knight ◽  
H. O. Senekjian ◽  
S. Sansom ◽  
E. J. Weinman
Keyword(s):  
Proximal Tubule ◽  
Water Absorption ◽  
Rat Kidney ◽  
Proximal Convoluted Tubule ◽  
Perfusion Solution ◽  
Hexose Sugars ◽  
Tubular Absorption ◽  
Rat Proximal Tubule ◽  
Fractional Absorption

The in vivo microperfusion technique was employed to examine urate absorption in the proximal convoluted tubule of the rat kidney using [2–14C]urate as the marker for fractional urate absorption. With NaCl as the perfusion solution, water absorption averaged 2.53 +/- 0.16 nl.min-1.mm tubule-1, and the fractional absorption of [2–14C]urate averages 11.6 +/- 1.0%/mm tubule. The addition of D-glucose (50 mg/100 ml) enhanced water absorption to 3.62 +/- 0.19 nl.min-1.mm tubule-1, but inhibited fractional urate absorption to 6.6 +/- 1.2%/mm tubule. Phloridzin (4.4 mg/100 ml), 2-deoxy-D-glucose (45.6 mg/100 ml), and 3-O-methyl-D-glucose (53.9 mg/100 ml) also inhibited the absorption of [2–14C]urate to the same degree as did D-glucose despite differing effects on water absorption. The addition of probenecid (2.8 mg/100 ml) to the NaCl perfusion solution had no effect on water absorption but inhibited [2–14C]urate absorption to 6.4 +/- 0.6%/mm tubule. The addition of both probenecid and phloridzin further reduced [2–14C-A1urate absorption to 3.8 +/- 0.7%/mm tubule. Probenecid alone had no effect on glucose transport. These studies suggest that the presence of either certain hexose sugars, phloridzin, or probenecid in the lumen of the proximal convoluted tubule inhibits the tubular absorption of urate.

Physiological evaluation of the isolated perfused rat kidney

1980 ◽  
Vol 238 (2) ◽  
pp. F71-F78 ◽  
Author(s):  
T. Maack
Keyword(s):  
Rat Kidney ◽  
Critical Evaluation ◽  
Proximal Convoluted Tubule ◽  
Urinary Concentration ◽  
Isolated Perfused Rat Kidney ◽  
Low Viscosity ◽  
Metabolic Functions ◽  
Perfusate Flow ◽  
Perfused Rat Kidney ◽  
Single Nephron

A critical evaluation of the functional properties of the isolated perfused rat kidney is necessary to assess the usefulness of the preparation for renal function studies. Clearance and micropuncture experiments in isolated perfused rat kidneys perfused with a plasmalike medium containing 7.5 g/100 ml albumin, glucose, and amino acids show that proximal convoluted tubule functions are well preserved. Proximal convoluted tubule reabsorption of organic substances, electrolytes, and fluid is near normal, the latter being directly related to the peritubular oncotic pressure. Superficial single nephron glomular filtration rate and glomerular permselectivity are also preserved. However, abnormalities in renal hemodynamics, urinary concentration-dilution, and excretion of fluid and electrolytes persist even in the best preparations. High renal perfusate flow, due mainly to the low viscosity of the perfusate, and altered distal nephron functions explain at least in part these abnormalities. Therefore, the isolated perfused rat kidney is a useful preparation to particularly study glomerular and proximal convoluted tubule functions. Recent development of a nonfiltering isolated perfused rat kidney model, with preserved renal perfusate flow and cellular integrity, also permits the study of transport and metabolic functions of proximal tubular cells independently of luminal events.

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