The role of bicarbonate and other buffers on isotonic fluid absorption in the proximal convolution of the rat kidney

1971 ◽  
Vol 330 (2) ◽  
pp. 149-161 ◽  
Author(s):  
K. J. Ullrich ◽  
H. W. Radtke ◽  
G. Rumrich ◽  
S. Kl�ss
Keyword(s):  
Rat Kidney ◽  
Fluid Absorption ◽  
Isotonic Fluid ◽  
Proximal Convolution

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 Reabsorption of lithium and phosphate by the rat kidney: Role of the parathyroids

1974 ◽  
Vol 5 (3) ◽  
pp. 196-203 ◽  
Author(s):  
Thomas H. Steele ◽  
Kathryn L. Dudgeon
Keyword(s):  
Rat Kidney

scholarly journals Expression of lysophosphatidic acid receptor 5 is necessary for the regulation of intestinal Na+/H+ exchanger 3 by lysophosphatidic acid in vivo

2018 ◽  
Vol 315 (4) ◽  
pp. G433-G442 ◽  
Author(s):  
Kayte A. Jenkin ◽  
Peijian He ◽  
C. Chris Yun
Keyword(s):  
Epithelial Cells ◽  
Lysophosphatidic Acid ◽  
Direct Evidence ◽  
Intestinal Epithelial Cells ◽  
Regulatory Role ◽  
Intestinal Epithelial ◽  
Fluid Absorption ◽  
Wild Type

Lysophosphatidic acid (LPA) is a bioactive lipid molecule, which regulates a broad range of pathophysiological processes. Recent studies have demonstrated that LPA modulates electrolyte flux in the intestine, and its potential as an antidiarrheal agent has been suggested. Of six LPA receptors, LPA5 is highly expressed in the intestine. Recent studies by our group have demonstrated activation of Na+/H+ exchanger 3 (NHE3) by LPA5. However, much of what has been elucidated was achieved using colonic cell lines that were transfected to express LPA5. In the current study, we engineered a mouse that lacks LPA5 in intestinal epithelial cells, Lpar5ΔIEC, and investigated the role of LPA5 in NHE3 regulation and fluid absorption in vivo. The intestine of Lpar5ΔIEC mice appeared morphologically normal, and the stool frequency and fecal water content were unchanged compared with wild-type mice. Basal rates of NHE3 activity and fluid absorption and total NHE3 expression were not changed in Lpar5ΔIEC mice. However, LPA did not activate NHE3 activity or fluid absorption in Lpar5ΔIEC mice, providing direct evidence for the regulatory role of LPA5. NHE3 activation involves trafficking of NHE3 from the terminal web to microvilli, and this mobilization of NHE3 by LPA was abolished in Lpar5ΔIEC mice. Dysregulation of NHE3 was specific to LPA, and insulin and cholera toxin were able to stimulate and inhibit NHE3, respectively, in both wild-type and Lpar5ΔIEC mice. The current study for the first time demonstrates the necessity of LPA5 in LPA-mediated stimulation of NHE3 in vivo. NEW & NOTEWORTHY This study is the first to assess the role of LPA5 in NHE3 regulation and fluid absorption in vivo using a mouse that lacks LPA5 in intestinal epithelial cells, Lpar5ΔIEC. Basal rates of NHE3 activity and fluid absorption, and total NHE3 expression were not changed in Lpar5ΔIEC mice. However, LPA did not activate NHE3 activity or fluid absorption in Lpar5ΔIEC mice, providing direct evidence for the regulatory role of LPA5.

Isotonic Fluid Absorption during Hysteroscopy Resulting in Severe Hyperchloremic Acidosis

2005 ◽  
Vol 103 (1) ◽  
pp. 203-204 ◽  
Author(s):  
Monika Schäfer ◽  
Britta S. Von Ungern-Sternberg ◽  
Edward Wight ◽  
Markus C. Schneider
Keyword(s):  
Fluid Absorption ◽  
Hyperchloremic Acidosis ◽  
Isotonic Fluid
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