Pioglitazone lowers systemic asymmetric dimethylarginine by inducing dimethylarginine dimethylaminohydrolase in rats

Shu Wakino, Koichi Hayashi, Satoru Tatematsu, Kazuhiro Hasegawa, Ichiro Takamatsu, Takeshi Kanda, Koichiro Homma, Kyoko Yoshioka, Naoki Sugano, Takao Saruta

Research output: Contribution to journalArticlepeer-review

99 Citations (Scopus)

Abstract

Peroxisome proliferator activated receptor-γ (PPARγ) ligands increase nitric oxide (NO) production and reduce systemic blood pressure. Asymmetric dimethylarginine (ADMA) is an endogenous nitric oxide synthase (NOS) inhibitor degraded by the enzyme dimethylarginine dimethylaminohydrolase (DDAH), which has two isoforms, DDAH-I and -II. In order to elucidate the mechanism whereby PPARγ ligands affect NO metabolism, their effects on the DDAH-ADMA pathway were investigated. Six-week-old male Wister-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were maintained with or without pioglitazone (PIO), a PPARγ ligand. After 4 weeks, serum ADMA levels and urinary daily NO excretion were analyzed. Tissue DDAH expression was examined by real-time polymerase chain reaction (PCR), immunoblotting, and immunohistochemistry. The results showed that PIO decreased serum ADMA and increased urinary NO excretion in both WKY and SHR. Also in both strains, the expression level of DDAH-II in the kidney was increased at transcriptional levels, although the DDAH-I level was unaffected. PIO lowered blood pressure in SHR, but not in WKY. We also demonstrated that PIO induced DDAH-II protein expression in Marbin-Dubin Canine Kidney (MDCK) cells, a renal tubular cell line. In conclusion, a PPARγ ligand was here found to increase NO production partly by upregulating tissue DDAH-II expression and decreasing systemic ADMA levels. This mechanism constitutes a direct action on renal tubular cells, but is less likely to be responsible for the blood pressure-lowering effects of PPARγ ligands. Since ADMA is one of the risk factors for cardiovascular events, this study provides compelling evidence that PPARγ ligands have the potential for reducing cardiovascular risks.

Original languageEnglish
Pages (from-to)255-262
Number of pages8
JournalHypertension Research
Volume28
Issue number3
DOIs
Publication statusPublished - 2005 Mar

Keywords

  • Asymmetric dimethylarginine (ADMA)
  • Dimethylarginine dimethylaminohydrolase
  • Marbin-Dubin Canine Kidney cells
  • Nitric oxide synthase
  • Peroxisome proliferator activated receptor-γ ligands

ASJC Scopus subject areas

  • Internal Medicine
  • Physiology
  • Cardiology and Cardiovascular Medicine

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