Alterations in membrane fatty acid unsaturation and chain length in hypertension as observed by¹h nmr spectroscopy

Alterations in fatty acid composition of membrane phospholipids in essential hypertension may account for altered membrane ion-transport and contractility properties of hypertensive tissues. To investigate the abnormalities in fatty acid composition in essential hypertension, we determined the degree of fatty acid unsaturation ([-CH = CH-]/[-CH-j]) and the average carbon chain length in membrane phospholipids of aorta, kidney and heart from spontaneously hypertensive rats (SHRs) and Wistar-Kyoto (WKY) rats by using 'H NMR spectroscopy. We found that the degrees of fatty acid unsaturation in the aorta and the kidney membranes were significantly lower in SHRs than in WKY rats (aorta, 0.5.1 ±0.0.1 versus 0.63 ± 0.02; kidney, 0.70 ±0.03 versus 0.84 ±O.OQ; p < 0.01). No significant difference could be detected in unsaturation in heart membranes between these two strains. For aorta, kidney and heart membranes, the average carbon chain lengths of fatty acid fractions of membrane phospholipids were significantly shorter for SHRs than for WKY rats (aorta, 15.1 ±0.6 versus 1S.3 ±1.6, p < 0.05; kidney, 14.5 ±0.7 versus 16.4 ±1.2, p < 0.05; heart, 17.3 ±1.6 versus 1K.S ±1.9, p0.06). The lower unsaturated fatty acid content in membrane phospholipids of the aorta and the kidney, with concomitant reduction in chain lengths, may arise from increased oxidation of fatty acid double bonds in hypertensive tissues and may account, in part, for tht- decreased aortic distensibility and abnormal kidney function associated with essential hypertension.