Na-P(i) cotransport sites in proximal tubule and collecting tubule of winter flounder (Pleuronectes americanus).
Localization of a recently described and cloned Na-Pi cotransport system from flounder was investigated by reverse transcription-polymerase chain reaction (RT-PCR) of microdissected tubules and by immunocytochemistry of kidney of winter flounder. Histological examination showed a small glomerulus, an extremely short proximal tubule PI with a selective affinity to Lens culinaris agglutinin from lentils, and an extensive second proximal tubule segment PII (> 90% of proximal tubules), consisting of cells with numerous apical clear vesicles and extensive amplification of basolateral cell membranes. PII merged with the collecting tubule/ collecting duct (CT/CD) system without a distal segment. By RT-PCR, PII cells revealed high levels of NaPi-II related RNA; low levels were also observed in CTs. Previously characterized antisera against different epitopes of flounder NaPi-II specifically labeled the basolateral regions of PII and the apical cell portion of CT/CD cells and of some PII cells. These results suggest that tubular secretion of P(i) occurs in PII of teleost fish with modulation of urinary P(i) content in the subsequent CT/CD system.
Elger
M
M
Institut für Anatomie und Zellbiologie I, Universität Heidelberg, Germany.
Werner
A
A
Herter
P
P
Kohl
B
B
Kinne
R K
RK
Hentschel
H
H
D000818:Animals; D002352:Carrier Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D005260:Female; D005432:Flounder; D007150:Immunohistochemistry; D007685:Kidney Tubules, Collecting / Q000737:chemistry*; D007687:Kidney Tubules, Proximal / Q000737:chemistry*; D037102:Lectins / Q000378:metabolism; D008297:Male; D008854:Microscopy, Electron; D037121:Plant Lectins; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D012194:RNA-Directed DNA Polymerase; D050608:Sodium-Phosphate Cotransporter Proteins; D027981:Symporters
D002352:Carrier Proteins; D037102:Lectins; D037121:Plant Lectins; D012333:RNA, Messenger; D050608:Sodium-Phosphate Cotransporter Proteins; D027981:Symporters; C033619:lentil lectin; D012194:RNA-Directed DNA Polymerase