Haemodynamic response to magnesium administration in mineralocorticoid-salt and two-kidney, one clip renovascular hypertension.
Recent interest has centred on the role of divalent cations in hypertension, particularly in relation to the renin-angiotensin system. This study was undertaken to determine the hypotensive effect of magnesium administration in relation to the state of activation of the renin-angiotensin system. The mean blood pressure (MBP) and heart rate (HR) response to either the acute intravenous administration of a pharmacological dose of MgSO4 or vehicle was determined in conscious mineralocorticoid-salt (DOCA-salt, low-renin) and two-kidney, one clip renovascular, high-renin hypertensive rats. Baseline MBP was higher in the renovascular than in the DOCA-salt rats, while there was no difference in HR or serum Mg concentration between the two. Following administration of MgSO4, serum Mg increased equally in both the DOCA-salt (1.4 +/- 0.8 to 4.9 +/- 0.16 mEq/l; P less than 0.001) and in the renovascular rats (1.8 +/- 0.14 to 4.4 +/- 0.27 mEq/l; P less than 0.001). Magnesium administration significantly lowered MBP over the 1-h infusion in the DOCA-salt (167 +/- 8 to 145 +/- 5 mmHg, P less than 0.001) but not the renovascular hypertensive rats (191 +/- 5 to 183 +/- 4, NS). We conclude that the blood pressure lowering effect of Mg is related, in part, to the state of activation of the renin-angiotensin system. The mechanism of this differential effect remains to be determined.
DiPette
D J
DJ
Department of Medicine, University of Texas Medical Branch, Galveston 77550.
Simpson
K
K
Rogers
A
A
Holland
O B
OB
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003900:Desoxycorticosterone; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D006978:Hypertension, Renovascular / Q000503:physiopathology*; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012084:Renin-Angiotensin System / Q000187:drug effects
D003900:Desoxycorticosterone; D008274:Magnesium