title: Magnesium supplementation attenuates, but does not prevent, development of hypertension in spontaneously hypertensive rats.
abstract: This study evaluated the effects of magnesium supplementation on the development of hypertension in spontaneously hypertensive rats (SHR) and assesses the actions of magnesium on extracellular and intracellular Ca2+, Na+, and K+ status. Ten-week-old SHR (n = 72) and Wistar-Kyoto rats (WKY) (n = 60) were divided into four groups: WKY, Mg-WKY (WKY receiving 650 mg/L Mg(2+)supplementation), SHR, and Mg-SHR (SHR receiving Mg2+). Rats were studied for 17 weeks. Serum and erythrocyte Mg2+ and Ca2+ (measured by atomic absorption spectroscopy) and Na+ and K+ (measured by flame photometry) were determined every 3 or 4 weeks. From 13 weeks of age, blood pressure (BP) was significantly elevated in SHR compared with age-matched WKY. BP was reduced (P < .01) in SHR after 10 weeks of Mg2+ supplementation and at 27 weeks of age, BP in SHR was 218 (12 mm Hg v 184 +/- 9 mm Hg) in Mg-SHR. From 18 weeks of age, serum and intracellular Mg2+ levels were significantly lower (P < .05) and from 21 weeks of age, erythrocyte Ca2+ was significantly higher in SHR than in WKY. Mg2+ supplementation normalized intracellular Mg2+ and Ca2+ concentrations in SHR. BP was inversely correlated with erythrocyte Mg2+ (r = -0.74, P < .01) and positively correlated with erythrocyte Ca2+ (r = 0.78, P < .001). In conclusion, long-term Mg2+ supplementation significantly attenuates, but does not prevent, the development of hypertension in SHR. Furthermore, intracellular Mg2+ deficiency and Ca2+ overload in SHR are normalized by Mg2+ treatment.
authors.affiliation: Department of Medicine, University of Witwatersrand, Johannesburg, South Africa. touyzr@ircm.qc.ca
authors.forename: R M
authors.initials: RM
authors.lastname: Touyz
authors.forename: F J
authors.initials: FJ
authors.lastname: Milne
mesh_terms: D000375:Aging / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000097:blood; D002412:Cations / Q000097:blood; D004032:Diet; D004912:Erythrocytes / Q000737:chemistry; D006973:Hypertension / Q000097:blood / Q000235:genetics* / Q000517:prevention & control*; D008274:Magnesium / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D008297:Male; D011188:Potassium / Q000097:blood; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012964:Sodium / Q000097:blood
chemical_list: D002412:Cations; D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium