title: Phosphodiesterase 5A inhibition induces Na+/H+ exchanger blockade and protection against myocardial infarction.
abstract: Acute phosphodiesterase 5A inhibition by sildenafil or EMD360527/5 promoted profound inhibition of the cardiac Na(+)/H(+) exchanger (NHE-1), detected by the almost null intracellular pH recovery from an acute acid load (ammonium prepulse) in isolated papillary muscles from Wistar rats. Inhibition of phosphoglycerate kinase-1 (KT5823) restored normal NHE-1 activity, suggesting a causal link between phosphoglycerate kinase-1 increase and NHE-1 inhibition. We then tested whether the beneficial effects of NHE-1 inhibitors against the deleterious postmyocardial infarction (MI) remodeling can be detected after sildenafil-mediated NHE-1 inhibition. MI was induced by left anterior descending coronary artery ligation in Wistar rats, which were randomized to placebo or sildenafil (100 mg kg(-1) day(-1)) for 6 weeks. Sildenafil significantly increased left ventricular phosphoglycerate kinase-1 activity in the post-MI group without affecting its expression. MI increased heart weight/body weight ratio, left ventricular myocyte cross-sectional area, interstitial fibrosis, and brain natriuretic peptide and NHE-1 expression. Sildenafil blunted these effects. Neither a significant change in infarct size nor a change in arterial or left ventricular systolic pressure was detected after sildenafil. MI decreased fractional shortening and the ratio of the maximum rate of rise of LVP divided by the pressure at the moment such maximum occurs, effects that were prevented by sildenafil. Intracellular pH recovery after an acid load was faster in papillary muscles from post-MI hearts (versus sham), whereas sildenafil significantly inhibited NHE-1 activity in both post-MI and sildenafil-treated sham groups. We conclude that increased phosphoglycerate kinase-1 activity after acute phosphodiesterase 5A inhibition blunts NHE-1 activity and protects the heart against post-MI remodeling and dysfunction.
authors.affiliation: Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina.
authors.forename: Néstor G
authors.initials: NG
authors.lastname: Pérez
authors.forename: Martín R
authors.initials: MR
authors.lastname: Piaggio
authors.forename: Irene L
authors.initials: IL
authors.lastname: Ennis
authors.forename: Carolina D
authors.initials: CD
authors.lastname: Garciarena
authors.forename: Celina
authors.initials: C
authors.lastname: Morales
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Escudero
authors.forename: Oscar H
authors.initials: OH
authors.lastname: Cingolani
authors.forename: Gladys
authors.initials: G
authors.lastname: Chiappe de Cingolani
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Yang
authors.forename: Horacio E
authors.initials: HE
authors.lastname: Cingolani
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000143:Acids / Q000494:pharmacology; D000818:Animals; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D006863:Hydrogen-Ion Concentration; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009203:Myocardial Infarction / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D010210:Papillary Muscles / Q000187:drug effects / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010735:Phosphoglycerate Kinase / Q000378:metabolism; D010879:Piperazines / Q000494:pharmacology; D011687:Purines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D000068677:Sildenafil Citrate; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors*; D013450:Sulfones / Q000494:pharmacology; D020257:Ventricular Remodeling / Q000187:drug effects
chemical_list: D000143:Acids; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D017923:Sodium-Hydrogen Exchangers; D013450:Sulfones; D000068677:Sildenafil Citrate; D010735:Phosphoglycerate Kinase; C505012:phosphoglycerate kinase 1, rat; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; C517384:Pde5a protein, rat