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.jpg): Failed to open stream: No such file or directory in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 117 Am+J+Physiol+Cell+Physiol
2014 ; 307
(6
): C532-41
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Uroguanylin inhibits H-ATPase activity and surface expression in renal distal
tubules by a PKG-dependent pathway
#MMPMID25031022
da Silva Lima V
; Crajoinas RO
; Carraro-Lacroix LR
; Godinho AN
; Dias JL
; Dariolli R
; Girardi AC
; Fonteles MC
; Malnic G
; Lessa LM
Am J Physiol Cell Physiol
2014[Sep]; 307
(6
): C532-41
PMID25031022
show ga
Cumulative evidence suggests that guanylin peptides play an important role on
electrolyte homeostasis. We have previously reported that uroguanylin (UGN)
inhibits bicarbonate reabsorption in a renal distal tubule. In the present study,
we tested the hypothesis that the bicarbonaturic effect of UGN is at least in
part attributable to inhibition of H(+)-ATPase-mediated hydrogen secretion in the
distal nephron. By in vivo stationary microperfusion experiments, we were able to
show that UGN inhibits H(+)-ATPase activity by a PKG-dependent pathway because
KT5823 (PKG inhibitor) abolished the UGN effect on distal bicarbonate
reabsorption and H89 (PKA inhibitor) was unable to prevent it. The in vivo
results were confirmed by the in vitro experiments, where we used fluorescence
microscopy to measure intracellular pH (pHi) recovery after an acid pulse with
NH4Cl. By this technique, we observed that UGN and 8 bromoguanosine-cGMP
(8Br-cGMP) inhibited H(+)-ATPase-dependent pHi recovery and that the UGN
inhibitory effect was abolished in the presence of the PKG inhibitor. In
addition, by using RT-PCR technique, we verified that Madin-Darby canine kidney
(MDCK)-C11 cells express guanylate cyclase-C. Besides, UGN stimulated an increase
of both cGMP content and PKG activity but was unable to increase the production
of cellular cAMP content and PKA activity. Furthermore, we found that UGN reduced
cell surface abundance of H+-ATPase B1 subunit in MDCK-C11 and that this effect
was abolished by the PKG inhibitor. Taken together, our data suggest that UGN
inhibits H(+)-ATPase activity and surface expression in renal distal cells by a
cGMP/PKG-dependent pathway.
|Animals
[MESH]
|Bicarbonates/metabolism
[MESH]
|Cell Membrane/*drug effects/enzymology
[MESH]
|Cyclic GMP-Dependent Protein Kinases/antagonists & inhibitors/*metabolism
[MESH]