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Updated: Jul 3, 2026

Study of the Functions and Activities of Neuronal K-Cl Co-Transporter KCC2 Using Western Blotting
Published on: December 9, 2022
Low levels of Na, K-ATPase and carbonic anhydrase II during choroid plexus development suggest limited involvement in
Pia Johansson1, Katarzyna Dziegielewska, Norman Saunders
1Department of Pharmacology, University of Melbourne, Parkville, Victoria 3010, Australia. piaaj@unimelb.edu.au
Unlabelled:
In the adult, cerebrospinal fluid (CSF) is produced by the actions of numerous transporters and enzymes creating ion gradients that drive the entry of water into the ventricles via the aquaporin-1 water channels (AQP1). It is not known when in development CSF secretion starts but, in the rat, it has been postulated to occur around the time of birth. However, recent evidence suggests that the secretion may start much earlier, as soon as the lateral choroid plexuses first appear (around E14).
Purpose:
To investigate the developmental profiles of two major enzymes responsible for CSF secretion in the adult, Na, K-ATPase (NKA) and carbonic anhydrase II (CAII).
Methods:
The developmental profiles of both enzymes were investigated using immunohistochemistry and Western Blot analysis in tissue from embryonic day (E) 15, 18, postnatal day (P) 0, 9 and adult rats.
Result:
Western Blot analysis showed low levels of NKA at E15 followed by a progressive increase with age. Immunohistochemistry confirmed the presence of NKA on the apical membrane of the lateral ventricular choroid plexus epithelium from E15 onwards. Western Blot analysis of CAII was complicated by its presence in blood, but the amount of protein increased with age. Immunohistochemically, CAII appeared in the lateral ventricular choroid plexus between P0 and P9.
Conclusions:
The low levels of NKA and CAII during early choroid plexus development indicate that other mechanisms, such as the previously described specific protein transfer across epithelial cells, may be involved in early CSF secretion and movement of water into the cerebral ventricles.
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