Colocalization of H(+)-ATPase and band 3 anion exchanger in rabbit collecting duct intercalated cells.
Two major types of intercalated cells (IC) have been previously defined in rabbit collecting duct: alpha-cells have a basolateral band 3-like anion exchanger and secrete H+, whereas beta-cells bind peanut agglutinin (PNA) apically and are believed to secrete HCO3-. To further define IC types, we double-labeled kidney sections with anti-H(+) -ATPase antibodies and with either an anti-band 3 antibody or PNA. We found four patterns of staining: 1) IC with apical H(+)-ATPase and basal band 3, a configuration consistent with ongoing H+ secretion, which prevailed in the inner stripe of outer medulla (OMCDi); 2) diffuse H(+)-ATPase labeling across the cell and basal band 3, which was most numerous in the outer stripe of outer medulla (OMCDo); 3) IC with "bright" apical peanut lectin, diffuse H(+)-ATPase, and no band 3, which was abundant in the cortical collecting duct (CCD) and probably represents HCO3(-)-secreting cells; and 4) "hybrid" cells with various staining combinations (e.g., apical lectin binding and apical H(+)-ATPase), which although they are uncommon, were seen in the CCD. Consistent with this immunocytochemical finding of hybrid cells, cell-sorting studies on isolated CCD IC showed that 6-18% of PNA-positive cells also stained positively for band 3. We conclude that 1) band 3-positive IC in the OMCD vary axially. Most OMCDi IC are probably active proton secretors, whereas up to one-half of OMCDo IC may be latent H+ secretors. 2) The diffuse H(+)-ATPase pattern in putative beta-cells differs from comparable results in the rat and is not consistent with a "reversed" alpha-cell. HCO3- secretion by beta-cells may be driven by an H+ extrusion mechanism other than the alpha-cell pump re-sorted to the basolateral membrane. 3) The possibility of hybrid cells that might combine alpha- and beta-cell transport proteins suggests a mechanism for functional reversal of collecting duct IC polarity.
Schuster
V L
VL
Renal Division, University of Iowa, Iowa City 52242.
Fejes-Tóth
G
G
Naray-Fejes-Tóth
A
A
Gluck
S
S
D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000032:analysis*; D000911:Antibodies, Monoclonal; D001639:Bicarbonates / Q000378:metabolism; D016650:Fluorescein-5-isothiocyanate; D005452:Fluoresceins; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D006822:Hybrid Cells / Q000737:chemistry; D007679:Kidney Medulla / Q000737:chemistry; D007685:Kidney Tubules, Collecting / Q000737:chemistry / Q000166:cytology*; D037102:Lectins / Q000378:metabolism; D019887:Peanut Agglutinin; D006180:Proton-Translocating ATPases / Q000032:analysis*; D011522:Protons; D011817:Rabbits; D013861:Thiocyanates
D001457:Anion Exchange Protein 1, Erythrocyte; D000911:Antibodies, Monoclonal; D001639:Bicarbonates; D005452:Fluoresceins; D005456:Fluorescent Dyes; D037102:Lectins; D019887:Peanut Agglutinin; D011522:Protons; D013861:Thiocyanates; D006180:Proton-Translocating ATPases; D016650:Fluorescein-5-isothiocyanate