Functional characterization of three intercalated cell subtypes in the rabbit outer cortical collecting duct.
AUTOR(ES)
Emmons, C
RESUMO
The distribution of Na(+)-independent Cl(-)-HCO3- exchange was studied in individual intercalated cells from in vitro perfused rabbit outer CCDs using dual excitation laser scanning confocal microscopy by measuring the pHi response to sequential removal of Cl- from both sides of the tubule. Three patterns of intracellular pH (pHi) response were observed. 39% of intercalated cells had only apical Cl(-)-HCO3- exchange (beta cell), 4% had only basolateral Cl(-)-HCO3- exchange (alpha cell), and 57% had both apical and basolateral Cl(-)-HCO3- exchange (gamma cell). Valinomycin-high K+ voltage clamping had no effect on the pHi response of intercalated cells with bilateral Cl(-)-HCO3- exchange. Although the mean rates of dpHi/dt following apical Cl- removal were similar in beta cells compared to gamma cells, a wide range of apical rates was seen among individual beta and gamma intercalated cells. Neither the apical nor the basolateral Cl(-)-HCO3- exchanger in gamma cells was inhibited by 0.5 mM H2DIDS. Binding of apical peanut lectin was seen both in beta cells and in gamma cells. In 41% of CCDs with four to seven intercalated cells studied, all intercalated cells were of the same subtype. We conclude that the majority of intercalated cells from the rabbit outer CCD have both apical and basolateral Na(+)-independent Cl(-)-HCO3- exchangers (gamma cells), which are stilbene-insensitive. Intercalated cells with only basolateral Cl(-)-HCO3- exchange are very uncommon in the rabbit outer CCD. There is a tendency for all intercalated cells in a given rabbit outer CCD to be of the same subtype (either all beta cells or all gamma cells), suggesting the presence of CCD intertubule heterogeneity at the same cortical level. This finding may account for intertubule differences in transepithelial H(+)-base transport.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=293800Documentos Relacionados
- Luminal vasopressin modulates transport in the rabbit cortical collecting duct.
- Active proton secretion and potassium absorption in the rabbit outer medullary collecting duct. Functional evidence for proton-potassium-activated adenosine triphosphatase.
- Cyclic adenosine monophosphate-stimulated anion transport in rabbit cortical collecting duct. Kinetics, stoichiometry, and conductive pathways.
- Hormonal regulation of proton secretion in rabbit medullary collecting duct.
- Cytochrome P450 metabolites of arachidonic acid are potent inhibitors of vasopressin action on rabbit cortical collecting duct.