Annamaria Stanzial

Omega-3 polyunsaturated fatty acid supplements and ambulatory blood pressure monitoring parameters in patients with mild essential hypertension

Objective To evaluate the effects of low doses of oM-3 polyunsaturated fatty acids on ambulatory blood pressure monitoring parameters in a group of mild essential hypertensives. Patients We studied 24 consecutive essential hypertensive patients from our outpatient clinic with mild hypertension (diastolic blood pressure ± 105 mmHg), no previous treatment for 4 weeks at least and no other disease. Methods After a 3-month run-in period, the patients entered an intervention phase and were given 3g oM-3 polyunsaturated fatty acids (85% eicosapentaenoic and docosahexaenoic acid concentrate) daily for 4 months; this phase was followed by a 4-month washout period. Ambulatory blood pressure monitoring was performed at the end of each phase; erythrocyte membrane fatty acids were assessed to check compliance. Results After 4 months of treatment, erythrocyte oM-3 polyunsaturated fatty acids significantly increased but average systolic and diastolic blood pressure and the heart rate did not significantly change; no significant variations were recorded in blood pressure or heart rate variability (assessed as blood pressure and heart rate SD) nor in the diurnal blood pressure rhythm. After washout, a significant decrease was observed in erythrocyte oM-3 polyunsaturated fatty acids but the ambulatory blood pressure monitoring parameters were not substantially modified. Conclusions The present data show that low doses of oM-3 polyunsaturated fatty acids as a single treatment are not effective in lowering blood pressure or the heart rate in mild essential hypertensive patients, despite a significant change in fatty acid cell membrane composition. Nor does this treatment seem likely to affect blood pressure variability or the diurnal rhythm.

Membrane fatty acids, glutathione-peroxidase activity, and cation transport systems of erythrocytes and malondialdehyde production by platelets in Laurence Moon Barter Biedl Syndrome

The fatty acid composition of erythrocyte membrane, the glutathione-peroxidase activity of erythrocytes and platelets, the production of malondialdehyde by platelets and the activity of the main systems of transmembrane cation transport have been studied in 5 members of a family, 2 of whom affected by Laurence-Moon-Barter-Biedl Syndrome. A remarkable increase of polyunsaturated fatty acids (particularly arachidonic acid) and of cholesterol/phospholipid molar ratio has been noted. This pattern of membrane lipids was associated to an increment of malondialdehyde production and an increase activity of glutathione-peroxidase. Serum retinol and a-tocopherol were in the normal range, whereas serum selenium was low in 3 out of 5 members. Moreover, the alteration of membrane lipids was associated to a decrease of the maximal velocity of Li-Na countertransport. We speculate that the enrichment of polyunsaturated fatty acids on the cell membranes may represent a condition favoring the lipoperoxidation and therefore the development of the retinitis pigmentosa characteristic feature of Laurence-Moon-Barter-Biedl Syndrome.

Erythrocyte and platelet fatty acids in retinitis pigmentosa

The fatty acid composition and the glutathione-peroxidase activity (GSH-Px) of erythrocytes and platelets, the production of malondialdehyde (MDA) by platelets and the activity of the main systems of transmembrane cation transport in erythrocyte have been studied in 12 patients (5 males and 7 females) affected by retinitis pigmentosa (RP). A remarkable increase of saturated fatty acids (SFA), particularly of stearic acid (C18:0), has been noted in these patients. The reduced unsaturated/saturated fatty acids ratio (PUFA/SFA) observed in both erythrocytes and platelets and the decrease of arachidonic acid in platelets may depend by an active peroxidation process as documented by the increase of MDA. Platelet glutathione-peroxidase (PTL-GSH-PX) and plasma retinol were in the normal range, whereas erythrocyte glutathione-peroxidase (E-GSH-PX), MDA and plasma alfa-tocopherol were increased in patients with RP. The activities of Na+-K+ pump, cotransport and Na+-Li+countertransport were normal in RP erythrocytes.

Impaired zinc and copper status and altered fatty acid cell membrane composition in essential hypertension.

The apparent antagonism between Zinc (Zn) and Copper (Cu) is a well-known phenomenon and has been documented in various chronic diseases. An impairment in Zn and Cu status has been shown in hypertensive animals (1), suggesting a possible relationship with the pathogenesis of hypertension. Zn and Cu are involved in lipid metabolism, and several studies indicated that a major aspect of Zn-Cu interaction may be related to the opposing effects on essential fatty acids (EFA) metabolism or by differential stimulation of the synthesis of prostaglandins (PGs), whose influence on blood pressure (BP) regulation has been widely documented (2). The conversion of C-18 polyunsaturated fatty acids (PUFA) into the longerchain metabolites proceeds through desaturation and elongation steps; desaturation processes are catalyzed by the Δ4-Δ5-Δ6 desaturases, which are the rate-limiting enzymes in the pathway, and whose activities specifically require Zn and Cu (2). Thus, Zn and Cu availability may modulate the balance of PGs precursors. Also, since C-20 and C-22 are the major PUFA found in phospholipids, most of the cellular functions (fluidity, permeability or the ion transport systems activity) are in some way related to their metabolism (3).