C. Barletbas et al., ARE THERE SEVERAL ISOFORMS OF NA,K-ATPASE ALPHA-SUBUNIT IN THE RABBITKIDNEY, The Journal of biological chemistry, 268(16), 1993, pp. 11512-11515
Previous pharmacologic and kinetic studies have demonstrated the axial
heterogeneity of the rabbit kidney tubule with regard to Na,K-ATPase.
To evaluate whether this heterogeneity might reflect the presence of
distinct isoforms of the alpha subunit of Na,K-ATPase, we used two mon
oclonal antibodies, IIC9 and IIE2 (G8), specific for the alpha1 and al
pha3 isoforms, respectively, as probes for changes in the specific act
ivity of Na,K-ATPase at the level of successive segments of the rabbit
nephron. Single, well defined nephron segments were obtained by micro
dissection of collagenase-treated kidney. Results indicate that IIC9 a
ntibody inhibited Na,K-ATPase activity by >90% in all the segments of
the nephron except the collecting duct. Conversely, IIE2 (G8) antibody
abolished Na,K-ATPase activity in the collecting duct, whereas it had
no effect in other nephron segments. These findings suggest that the
rabbit collecting duct preferentially expresses a distinct isoform of
Na,K-ATPase catalytic subunit, which is presumably alpha3-like, in agr
eement with previous pharmacologic and kinetic observations, whereas o
ther nephron segments would express the alpha1 isoform.