Oral calcium supplementation ambulatory blood pressure and relation to changes in intracellular ions and sodium-hydrogen exchange.

BACKGROUND: Calcium (Ca2+) supplementation has been shown paradoxically to reduce intracellular Ca2+ and induce vascular relaxation. The aim of the study was to assess 24-h blood pressure (BP) change after Ca2+ supplementation and to investigate its relation to changes in intracellular ions and the activity of the first isoform of sodium-hydrogen exchange (NHE-1) in subjects with hypertension and type 2 diabetes. METHODS: This parallel, randomized controlled, single-blinded trial, consisted of 31 patients with type 2 diabetes, and hypertension who were allocated to receive 1,500 mg of Ca2+ per day (n = 15) or no treatment (n = 16) for 8 weeks. RESULTS: In the Ca2+ group a decrease of 1.7 +/- 2.7 mm Hg (mean +/- SE) P = 0.52 for mean 24-h systolic BP (SBP) and 2.1 +/- 1.5 mm Hg, P = 0.19 for mean 24-h diastolic BP (DBP) was recorded. Whereas in the control group an increase of 1.4 +/- 2.7 mm Hg, P = 0.59 for mean 24-h SBP and 1.2 +/- 2.8 mm Hg, P = 0.83 for mean 24-h DBP was observed. Intraplatelet Ca2+ decreased whereas intraplatelet magnesium (Mg2+) and erythrocyte K+ increased in the intervention group. Change in mean 24-h SBP in the pooled group correlated with both change in intraplatelet Ca2+ (r = 0.49, P < 0.05) and NHE-1 activity (r = 0.6, P < 0.001). The contribution of intraplatelet Ca2+ was attenuated when both parameters were entered in a multivariate regression model. CONCLUSIONS: The present study shows a weak, statistically nonsignificant trend towards association of Ca2+ supplementation on 24-h BP in hypertensive subjects with type 2 diabetes. However, our results indicated an interrelation of [Ca2+]i levels and NHE-1 activity on BP in patients with hypertension and type 2 diabetes.

Further examination of antiradical properties of Crocus sativus stigmas extract rich in crocins.

Data for antiradical properties of saffron extract and its bioactive constituents (crocins, crocetin) are limited and poorly discussed in comparison with those of extracts containing potent scavengers. Further examination was sought using the Folin-Ciocalteu (F-C) reagent and various free radical species produced in cell-free or cell model systems. Oregano and turmeric methanol extracts, rich in well established scavengers, and also crocetin, rosmarinic acid, and curcumin, representing the major types of constituents in the three studied extracts, were used as "reference". On the same weight basis, saffron extract activity was found to be rather negligible in all cell-free systems with regard to that found for reference ones. On the contrary, in the human monocyte system, saffron extracts or free crocetin were found to reduce ROS production as effectively as the phenolic antioxidants. Our findings point out that saffron extracts exhibit a remarkable intracellular antioxidant activity that cannot be revealed using assays repeatedly applied to the evaluation of phenolic-type antioxidants.