TITLE:
The acid-base regulation by renal proximal tubule
AUTHORS:
Shoko Horita, Osamu Yamazaki, Motonobu Nakamura, Hideomi Yamada, Masashi Suzuki, George Seki
KEYWORDS:
PRTA; NHE; NBCe1; V-ATPase
JOURNAL NAME:
Open Journal of Molecular and Integrative Physiology,
Vol.3 No.4,
November
14,
2013
ABSTRACT:
The kidney plays quite an important role in the regulation of acid-base homeostasis. The dysfunction of renal acid-base regulation
causes diseases such as developmental disorder, bone malformation, calcification
of eye and brain, etc. In the kidney, this regulation is performed, to a
considerable part, in the proximal tubule of the nephron. In the luminal side
the key player is sodium-proton exchanger type 3 (NHE3), whereas
sodium-bicarbonate cotransporter (NBCe1) plays the critical role in the
basolateral side. In the cytoplasm there is carbonic anhydrase type 2 (CAII)
that intermediates the conversion of CO2/ . Interestingly, in human,
mutations have been found in NBCe1 and CAII but not in NHE3 so far. Mutations
of NBCe1 lead to severe proximal renal tubular acidosis (pRTA) and other
systemic manifestations. In animal model studies, however, the relative
contribution of NHE3 to proximal tubule functions remains controversial.
Recently, V-ATPase with renal specific subunits is suggested to have some roles
in the regulation of proximal tubule functions. In this review, we will
discuss the regulation of acid-base transport in the proximal tubule and the
updates.