ALTERATIONS IN MEMBRANE FATTY-ACID UNSATURATION AND CHAIN-LENGTH IN HYPERTENSION AS OBSERVED BY H-1-NMR SPECTROSCOPY

Alterations in fatty acids of membrane phospholipids in essential hype rtension may account for altered membrane ion transport, elasticity, a nd contractility properties of hypertensive tissues. To investigate th e abnormalities in membrane fatty acids in essential hypertension, the degree of fatty acid unsaturation ([-CH=CH-]/[-CH3]), the average car bon chain length, ratio of glycerol to fatty acyl chains, ratio of pho sphatidylcholine to fatty acyl chains, and the ratio of free and acyla ted cholesterol to fatty acyl chains in fatty acid fractions of membra ne phospholipids of aorta, kidney, and heart were determined in sponta neously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats by H-1 nuc lear magnetic resonance (NMR) spectroscopy. The degrees of fatty acid unsaturation in the aorta and the kidney membranes were significantly lower in SHR than in WKY rats (aorta, 0.53 +/- 0.01 v 0.63 +/- 0.01, n = 5, P = .01; kidney, 0.70 +/- 0.01 v 0.84 +/- 0.03, n = 10, P = .01) . No significant difference could be detected in fatty acid unsaturati on in heart membranes between these two strains. For aorta, kidney, an d heart membranes, the average carbon chain lengths of fatty acid frac tions of membrane phospholipids were significantly shorter for SHR tha n for WKY rats (aorta, 15.1 +/- 0.2 v 18.3 +/- 0.7, n = 5, P = .02; ki dney, 14.5 +/- 0.2 v 16.4 +/- 0.4, n = 10, P = .01; heart, 17.3 +/- 0. 5 v 18.8 +/- 0.6, n = 10, P = .05). The lower unsaturated fatty acid c ontent in membrane phospholipids of the aorta and the kidney, with con comitant reduction in average chain length, may arise from increased o xidation of fatty acid double bonds in hypertensive tissues and may ac count, in part, for the increased aortic stiffness and abnormal kidney function associated with essential hypertension. Whether the lower un saturated fatty acid content and decreased carbon chain length of phos pholipid membranes in the aorta and the kidney are a cause or a conseq uence of the high blood pressure, however, remains unknown. (C) 1998 A merican Journal of Hypertension, Ltd.