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Abstract: PO1824

Effect of Tochu Extract and Its Component Geniposidic Acid on Renal Hemodynamics and Hypertensive Renal Damage

Session Information

Category: Hypertension and CVD

  • 1403 Hypertension and CVD: Mechanisms

Authors

  • Tojo, Akihiro, Dokkyo Medical University, Mibu, Tochigi, Japan
  • Satonaka, Hiroshi, Dokkyo Medical University, Mibu, Tochigi, Japan
  • Ishimitsu, Toshihiko, Dokkyo Medical University, Mibu, Tochigi, Japan
Background

Aqueous extract of Eucommia ulmoides (Tochu) leaf is used as Tochu tea in Japan and has the effect of lowering blood pressure. We investigated the effects of Tochu extract and its component geniposidic acid on renal hemodynamics and hypertensive renal damage in Dahl salt-sensitive hypertensive rats (DS).

Methods

DS rats received 1% saline solution from 4 weeks of age. After the blood pressure reached 150 mmHg or higher at 9 weeks of age, the rats were treated with 1% saline solution (DSHS), or 1% saline added 0.5% Tochu extract (DSHS + T) or, 1% saline added 0.2% geniposidic acid (DSHS + G) for another 4 weeks. DS rats fed with tap water were used as controls (DSLS). At 13 weeks, renal plasma flow (RPF) was measured by renal clearance study, and immunostaining and PCR of NADPH oxidase, eNOS, sodium transporters and fibrotic factors were performed.

Results

Blood pressure was significantly increased in DSHS rats compared to DSLS rats (196 vs.144 mmHg, p<0.01), which was significantly decreased in DSHS + T rats (158 mmHg) and DSHS + G rats (162 mmHg). Vascular resistance of afferent arterioles was significantly increased in DSHS rats compared to DSLS rats, and was decreased in both DSHS + T and DSHS + G rats. RPF was significantly higher in DSHS + T rats than in DSHS rats associated with decreased renal vascular resistance (p <0.05). In DSHS rats, NADPH oxidase expression and superoxide production were increased, with increased TGF-beta, procollagen 1, fibronectin and renal fibrosis. These were suppressed in DSHS + T and DSHS + G rats. NO production by eNOS was decreased in DSHS rats, but the treatment groups increased eNOS expression and NO production in the vascular endothelium, resulting in decreased renal vascular resistance and improved renal blood flow. Urinary sodium excretion was significantly higher in DSHS rats than in DSLS rats with decreased sodium chloride co-transporter (NCC). However, there was no further change in NCC or other sodium transporters in the treatment groups, and the high urinary Na excretion in the treatment groups was due to the effect of increased RPF.

Conclusion

Tochu and geniposidic acid suppressed NADPH oxidase and increased eNOS in DS rats, resulting in improved blood pressure, renal hemodynamics and renal damage.

Funding

  • Commercial Support –