Immunomorphometric study of rat renal inner medulla.
We utilized immunofluorescent immunolabeling of renal tissue sections to identify and count tubules at specified depths of the rat renal inner medulla. We used primary antibodies to aquaporin-1 (AQP1; labeling thin descending limbs), aquaporin-2 (AQP2; labeling inner medullary collecting ducts), the rat kidney-specific chloride channel (ClC-K1; labeling thin ascending limbs), and von Willebrand factor (labeling descending vasa recta). Secondary antibodies conjugated to different fluorophores were used, giving up to a three-color display. Labeled structures were then identified and counted. At each level sampled in the inner medulla, many more thin limbs were labeled by ClC-K1 than AQP1. In addition, thin limbs were found to label with antibodies to ClC-K1 on both sides of their hairpin turns. We conclude that the descending thin limbs shift from expressing AQP1 to expressing ClC-K1 some distance before the point where they turn and begin to ascend. Mathematical models can use our quantitative data to explore implications for the urine-concentrating mechanism.
Mejia
Raymond
R
Mathematical Research Branch, National Institutes of Health, Bethesda, Maryland 20892-2690, USA. ray@helix.nih.gov
Wade
James B
JB
D000818:Animals; D000906:Antibodies; D051398:Aquaporin 1; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins / Q000032:analysis* / Q000276:immunology; D002645:Chickens; D018118:Chloride Channels / Q000032:analysis* / Q000276:immunology; D005455:Fluorescent Antibody Technique; D007671:Kidney Concentrating Ability / Q000502:physiology; D007679:Kidney Medulla / Q000737:chemistry* / Q000166:cytology; D008138:Loop of Henle / Q000737:chemistry / Q000166:cytology; D008297:Male; D011817:Rabbits; D051381:Rats; D011910:Rats, Brattleboro; D014841:von Willebrand Factor / Q000032:analysis / Q000276:immunology
D000906:Antibodies; C496022:Aqp1 protein, rat; C496025:Aqp2 protein, rat; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D018118:Chloride Channels; C082118:Clcnka protein, rat; D014841:von Willebrand Factor; D051398:Aquaporin 1