P2X receptors trigger intracellular alkalization in isolated perfused mouse medullary thick ascending limb.
Bottom Line: The renal outer medullary K(+) channel (ROMK) is sensitive to intracellular pH where a reduction leads to closing of ROMK.We speculated that P2X receptor stimulation in the TAL could lead to changes in pHi , leading to a reduction in NaCl transport.This increased NHE3 activity causes H(+) secretion in the mTAL and provides further support that the TAL is a site of urinary acidification.
Affiliation: Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus C, Denmark.Show MeSH
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Mentions: A recent study from our group has established that furosemide causes an intracellular alkalization in the mTAL through increased apical NHE3-mediated H+ secretion (de Bruijn et al. 2013). To investigate whether the ATP-induced intracellular alkalization occurs by the same mechanism, basolateral ATP was tested in the presence of the specific NHE3 blocker #4167 (Reuter et al. 2008). Figure5a shows that luminal #4167 (1 μm) caused a significant intracellular acidification (ΔpH −0.35 ± 0.02, n = 8, Fig.5b). During this NHE3 inhibition, the ATP-induced alkalization was completely abolished in five of eight experiments, whereas in three experiments, the alkalization was strongly attenuated. These data indicate that apical NHE3 activity is required for the ATP-induced alkalization.
Affiliation: Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus C, Denmark.