P-388: Linkage between altered rbc free magnesium and plasma membrane and circulating lipids in hypertension: an 1H- and 31P-NMR spectroscopy study

• Published in: American journal of hypertension Vol. 17; no. S1; pp. 175A - 176A
• Main Authors: Resnick, Lawrence M., Gupta, Raj K.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.05.2004
• Subjects: Lipids; Magnesium; NMR Spectroscopy
• ISSN: 0895-7061; 1941-7225
• DOI: 10.1016/j.amjhyper.2004.03.462

To study the possible origins of altered ion content in hypertension, 1H- and 31P-NMR spectroscopy was utilized to measure RBC cytosolic free magnesium levels (Mgi) which were compared with the degree of fatty acid unsaturation (DB/CH3),5 -unsaturated fatty acids (5/CH3, including arachidonate, DHA, EPA), average fatty acid chain length (CL), and relative cholesterol content (Chol/PC) in lipids extracted from RBC membranes and plasma of 25 subjects (control Nl, n=7, BP=138″4/83″2 mmHg), untreated essential hypertension (EH, n=8, BP=157″5/97″4 mmHg), and drug-treated EH (EH-Rx, n=10, BP=143″4/84″3 mmHg). Compared to Nl, EH had lower Mgi (168“8 vs 202”12 μM, p=0.01) and greater Chol/PC (p=0.03) content, while fatty acid CL (p=0.05),5 /CH3 (p=0.02), and DB/CH3 in EH membranes (p=0.006) and plasma (p=0.008) were all lower. Furthermore, DB/CH3 (r=0.795, p=0.001) and Chol/PC content (r=0.566, p=0.04) in plasma vs membrane fractions were closely correlated. For all subjects, Mgi was directly related to CL (r=0.711, p=0.002) and DB/CH3 (r=0.54, p=0.02), and was inversely related to Chol/PC (r= −0.563, p=0.01). Clinically, DBP was inversely related to Mgi (r=-0.622, p=0.002) and DB/CH3 (plasma, r=−0.735, p=0.005; membranes, r=−0.80, p=0.001); and was positively related to chol/PC (plasma, r=0.689, p=0.02). These data demonstrate: i) significant linked alterations of deficient Mgi, shorter and more saturated fatty acids, and relatively increased cholesterol content in EH, and ii) that RBC membrane lipids are related to and thus may be influenced by circulating lipids. Lastly, since membrane fluidity, ion transport, and thus steady-state ion levels are determined by plasma membrane fatty acid species , these data iii) may also help to explain how altered circulating fatty acids and/or cholesterol of dietary or other origin may influence Mgi, in turn an established determinant of vascular tone and blood pressure as well as insulin resistance. As such, ionic mechanisms may mediate the blood pressure and metabolic effects of altered cellular lipid metabolism. Am J Hypertens (2004) 17, 175A–176A; doi: 10.1016/j.amjhyper.2004.03.462