Submitted March 17, 2002
Returned for revision April 8, 2002
Accepted August 7, 2002
Female Reproductive Tract
Expression, Immunolocalization, and Functional Activity of
Na+/H+ Exchanger Isoforms in Mouse
Endometrial Epithelium
X.F. Wang 1,
M.K. Yu 2,
S.Y. Lam 2,
K.M. Leung 2,
J.L. Jiang 2,
P.S. Leung 2,
W.H. Ko 2,
P.Y. Leung 2,
S.B.C. Chew 2,
C.Q. Liu 3,
C.M. Tse 4,
H.C. Chan 2*
1 The Chinese University of Hong Kong
2 The Chinese Univ. of Hong Kong
3 Shanghai Institute of Planned Parenthood Research,China
4 The Johns Hopkins University,Baltimore,USA
* To whom correspondence should be addressed. E-mail: hsiaocchan{at}cuhk.edu.hk.
Abstract
The luminal fluid microenvironment of the uterus is
important for sperm capacitation and embryo development.
In an attempt to understand the possible role of
Na+/H+ exchangers (NHEs) in uterine
function, the mRNAs of different NHE isoforms as well as
their subcellular localization (apical versus basolateral)
and functional activity were investigated in mouse
endometrial epithelial cells using RT-PCR,
immunohistochemistry and intracellular pH (pHi)
measurement techniques. The presence of NHE1, NHE2 and
NHE4, but not NHE3, mRNAs were revealed by RT-PCR.
Immunostaining showed that NHE1, NHE2 and NHE4 were
present in both apical and basolateral membranes. The
pHi recovery from intracellular acidification
was Na+-dependent; however, the rate of pHi
recovery depending on basolateral Na+ was 12.4
times faster than that depending on apical Na+.
The Na+-dependent rate of pHi recovery was also
amiloride-inhibitable indicating H+ extrusion
through NHEs; however, the amiloride sensitivity of the
apical membrane was less than that of the basolateral
membrane, suggesting the involvement of different types of
NHEs in the two membranes. The results indicate that the
basolaterally located NHE1, NHE2, NHE4, in addition to
participating in the homeostatic control of intracellular
pH, may play a role in H+ extrusion in order to
achieve transepithelial HCO3- secretion. The
apically located NHEs may be involved in mediating
Na+ absorption as alternatives of or
complementary to epithelial Na+ channels.
Key words:
Female Reproductive Tract •
Uterus
