Volume 89, Issue 4, April (2003), pp. 539-549 © The Author 2003
doi:10.1079/BJN2002810

Medline/PubMed Citation | Related Articles in PubMed | Download to Citation Matcher  

Effect of a methionine-supplemented diet on the blood pressure of Wistar–Kyoto and spontaneously hypertensive rats

Sophie Robin^1,*, Véronique Maupoil¹, Frédérique Groubatch¹, Pascal Laurant¹, Alain Jacqueson² and Alain Berthelot^1
1Laboratoire de Physiologie, Pharmacologie et Nutrition Préventive Expérimentale and 
²Laboratoire de Toxicologie, UFR Médecine et Pharmacie, 4 Place Saint-Jacques, 25030 Besançon cedex, France

 (Received 8 February 2002–Revised 30 October 2002–Accepted 8 November 2002)

The objectives of the present work were to evaluate the effect of a methionine-supplemented diet as a model of hyperhomocysteinaemia on the systolic blood pressure (BP) and vasomotor functions of aortic rings in Wistar–Kyoto (WKY) and spontaneously hypertensive rats (SHR). WKY and SHR rats, randomised into four groups, were fed a normal semisynthetic diet or a methionine (8 g/kg)-supplemented diet for 10 weeks. Systolic BP was measured non-invasively. At the end of the experiment, plasma homocysteine, methionine, cysteine and glutathione levels were determined. Vasoconstriction and vasodilatation of aortic rings were measured. The methionine-supplemented diet induced a significant increase in plasma homocysteine and methionine concentration in both WKY and SHR rats, an increase in plasma cysteine concentrations in WKY rats and an increase in the glutathione concentration in SHR. The systolic BP of WKY rats fed the methionine-supplemented diet increased significantly (P<0·01), whereas systolic BP was reduced in SHR. An enhanced aortic responsiveness to noradrenaline and a decreased relaxation induced by acetylcholine and bradykinin were observed in the WKY rats fed the methionine-enriched diet. In SHR, the bradykinin-induced relaxation was reduced, but the sodium nitroprusside response was increased. In conclusion, a methionine-enriched diet induced a moderate hyperhomocysteinaemia and an elevated systolic BP in WKY rats that was consistent with the observed endothelial dysfunction. In SHR, discrepancies between the decreased systolic BP and the vascular alterations suggest more complex interactions of the methionine-enriched diet on the systolic BP. Further investigations are needed to understand the paradoxical effect of a methionine-rich diet on systolic BP.

Abbreviations: BP; blood pressure; Cys; cysteine; EC₅₀; half effective concentration; Hcy; homocysteine; HHcy; hyperhomocysteinaemia; Met; methionine; SHR; spontaneously hypertensive rat; WKY; Wistar–Kyoto rat
Corresponding Author: Dr Sophie Robin, fax +33 3 81 66 56 91, email robin.sophie@caramail.com.

Keywords:
Hypertension: Homocysteine: Aortic rings