Phosphodiesterase 5A inhibition decreases NHE-1 activity without altering steady state pH i: Role of phosphatases

Romina G. Díaz, Mariela B. Nolly, Carolina Massarutti, María J. Casarini, Carolina D. Garciarena, Irene L. Ennis, Horacio E. Cingolani, Néstor G. Pérez

Research output: Contribution to journalArticle

Abstract

Background/Aims: This study aimed to identify the signaling pathway for the proposed link between phosphodiesterase-5A (PDE5A) inhibition and decreased cardiac Na + /H + exchanger (NHE-1) activity. Methods: NHE-1 activity was assessed in rat isolated papillary muscles by the Na + -dependent initial pH i recovery from a sustained acidosis (ammonium prepulse). ERK1/2, p90RSK and NHE-1 phosphorylation state during acidosis was determined. Results: PDE5A inhibition (1 μmol/L sildenafil, SIL) did not modify basal pH i but significantly blunted pH i recovery after sustained acidosis. Although preventing ERK1/2- p90RSK signaling pathway (10 μmol/L U0126) mimicked SIL effect, SIL did not blunt the acidosis-mediated increase in kinases activation. SIL+U0126 did not show additive effect on NHE-1 activity. Then, we hypothesized that SIL could be activating phophasatases (PP1 and/or PP2A) to directly dephosphorylate NHE-1 despite preserved ERK1/2-p90RSK activation. Non-specific phosphatases inhibition (1 μmol/L okadaic acid) canceled SIL effect on pH i recovery from acidosis. Same result was observed by inhibiting PP2A either with a lower dose of okadaic acid (1 nmol/L) or, more specifically, with 100 μmol/L endothall. Consistently, NHE-1 phosphorylation at Ser703 increased after acidosis, SIL prevented this effect and PP2A inhibition (endothall) reverted SIL effect. Conclusion: We suggest that PDE5A inhibitors decrease NHE-1 phosphorylation and activity through a mechanism that involves PP2A activation.

Original languageEnglish (US)
Pages (from-to)531-540
Number of pages10
JournalCellular Physiology and Biochemistry
Volume26
Issue number4-5
DOIs
StatePublished - 2010

Keywords

  • NHE-1
  • Phosphodiesterase 5A
  • Protein kinase G
  • Protein phosphatase 2A

ASJC Scopus subject areas

  • Physiology

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    Díaz, R. G., Nolly, M. B., Massarutti, C., Casarini, M. J., Garciarena, C. D., Ennis, I. L., Cingolani, H. E., & Pérez, N. G. (2010). Phosphodiesterase 5A inhibition decreases NHE-1 activity without altering steady state pH i: Role of phosphatases. Cellular Physiology and Biochemistry, 26(4-5), 531-540. https://doi.org/10.1159/000322321