Immunocytochemical studies of the Na-K-Cl cotransporter of shark kidney

Daniel Biemesderfer, John A Payne, Christian Y. Lytle, Bliss Forbush

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

The Na-K-Cl cotransporter (NKCC or BSC) has been described in numerous secretory and reabsorptive epithelia and is an important part of the mechanism of NaCl reabsorption in both the mammalian and elasmobranch kidneys. We have recently developed a panel of four monoclonal antibodies (MAbs) raised to the 195-kDa Na-K-Cl cotransport protein of the shark rectal gland (sNKCCl), which is expressed along the basolateral plasma membrane of secretory cells in this tissue (29). Here, we report immunologie studies of the Na-K-Cl cotransporter in the kidney of the dogfish shark Squalus acanthias. Western blot analysis of shark renal microsomes using MAbs J3, J7, and J25 identified proteins of - 195 and 150 kDa, whereas MAb J4 was not reactive. To define the cellular and subcellular distribution of the cotransport protein, immunofluorescence and immunoelectron microscopy studies were performed on fixed kidneys. Immunofluorescence microscopy on semithin (0.5-um) cryosections demonstrated that MAbs J3, J7, and J25 intensely stained the apical plasma membrane of all distal tubule segments. Weak staining was also seen along the basolateral membrane of most distal nephrons. Immunoelectron microscopy confirmed this observation and showed that some of these segments were morphologically similar to diluting segments from other species. MAbs also reacted with the brush border and, to a lesser extent, the basolateral membrane of proximal tubules. This study supports the hypothesis that the lateral bundle zone of the elasmobranch kidney functions as a countercurrent exchanger and is consistent with the presence of multiple isoforms of the Na-K-Cl cotransporter in the shark kidney.

Original languageEnglish (US)
JournalAmerican Journal of Physiology
Volume270
Issue number6 PART 2
StatePublished - 1996
Externally publishedYes

Keywords

  • Bumetanide-sensitive sodium chloride transport
  • Elasmobranch
  • Nephron
  • Sodium reabsorption

ASJC Scopus subject areas

  • Physiology (medical)
  • Physiology

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