Angiotensin II upregulates the expression of vasopressin V2 mRNA in the inner medullary collecting duct of the rat

Metabolism ◽  
2003 ◽  
Vol 52 (3) ◽  
pp. 290-295 ◽  
Author(s):  
Norman L.M. Wong ◽  
Joseph K.C. Tsui
Keyword(s):  
Angiotensin Ii ◽  
Collecting Duct ◽  
Inner Medullary Collecting Duct ◽  
Medullary Collecting Duct

Renal medullary plasma flow rate and reabsorption of salt and water from inner medullary collecting duct

1987 ◽  
Vol 65 (12) ◽  
pp. 2415-2421 ◽  
Author(s):  
W. A. Cupples ◽  
H. Sonnenberg
Keyword(s):  
Blood Flow ◽  
Sodium Chloride ◽  
Angiotensin Ii ◽  
Flow Rate ◽  
Plasma Flow ◽  
Collecting Duct ◽  
Urine Osmolality ◽  
Renal Circulation ◽  
Inner Medullary Collecting Duct ◽  
Medullary Collecting Duct

It has been proposed that medullary washout secondary to increased blood flow will limit maximal urine osmolality and reabsorption of salt and water from the inner medullary collecting duct. We have tested this prediction. The function of the inner medullary collecting duct was examined by microcatheterization. Acetylcholine was infused directly into the renal circulation, captopril was infused intravenously, and angiotensin II was infused into the renal circulation in rats which also received captopril. Medullary plasma flow rate, measured by dye–dilution in parallel experiments, was not significantly increased by acetylcholine; it was increased 30% (p < 0.02) by systemic infusion of captopril, and was returned to control by angiotensin II. Acetylcholine increased both urine flow rate and sodium excretion (p < 0.01, p < 0.001, respectively), while captopril increased only sodium excretion (p < 0.025). Angiotensin II blocked the natriuresis due to captopril. None of the treatments altered urine osmolality (p > 0.4 in all cases). Acetylcholine increased the loads of water, sodium, chloride, and total solute delivered to the inner medullary collecting duct. Angiotensin II reduced delivery of water and solutes compared with captopril alone. None of the treatments affected load dependency of reabsorption of water, sodium, chloride, or total solute in the inner medullary collecting duct. We conclude that there is, at most, a weak interaction between medullary blood flow and reabsorption from the inner medullary collecting duct.

Water permeability of apical and basolateral cell membranes of rat inner medullary collecting duct

1990 ◽  
Vol 259 (6) ◽  
pp. F986-F999 ◽  
Author(s):  
B. Flamion ◽  
K. R. Spring
Keyword(s):  
Water Flow ◽  
Water Permeability ◽  
Cell Membranes ◽  
Apical Membrane ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Volume Regulatory Decrease ◽  
Water Permeation ◽  
Inner Medullary Collecting Duct ◽  
Medullary Collecting Duct

To quantify the pathways for water permeation through the kidney medulla, knowledge of the water permeability (Posmol) of individual cell membranes in inner medullary collecting duct (IMCD) is required. Therefore IMCD segments from the inner two thirds of inner medulla of Sprague-Dawley rats were perfused in vitro using a setup devised for rapid bath and luminal fluid exchanges (half time, t1/2, of 55 and 41 ms). Differential interference contrast microscopy, coupled to video recording, was used to measure volume and approximate surface areas of single cells. Volume and volume-to-surface area ratio of IMCD cells were strongly correlated with their position along the inner medullary axis. Transmembrane water flow (Jv) was measured in response to a variety of osmotic gradients (delta II) presented on either basolateral or luminal side of the cells. The linear relation between Jv and delta II yielded the cell membrane Posmol, which was then corrected for membrane infoldings. Basolateral membrane Posmol was 126 +/- 3 microns/s. Apical membrane Posmol rose from a basal value of 26 +/- 3 microns/s to 99 +/- 5 microns/s in presence of antidiuretic hormone (ADH). Because of amplification of basolateral membrane, the ADH-stimulated apical membrane remained rate-limiting for transcellular osmotic water flow, and the IMCD cell did not swell significantly. Calculated transcellular Posmol, expressed in terms of smooth luminal surface, was 64 microns/s without ADH and 207 microns/s with ADH. IMCD cells in anisosmotic media displayed almost complete volume regulatory decrease but only partial volume regulatory increase.

Sign in / Sign up

Export Citation Format

Share Document