Protective effect of quercetin against in vitro erythrocyte rheology alterations produced by arsenic.

Humans are exposed to heavy metals such as arsenic (As), through contaminated food and drinking water. The effect of As on RBC membrane is one of the most important biological effects. In a previous work, we have studied the AsVin vitro effect on erythrocytes biophysical properties discovering alterations regarding aggregability deformability, cell morphology, membrane fluidity and osmotic response. We have also observed that the presence of the metal produces an oxidative stress in RBCs that might be the origin of rheological impairment. In the present work we analyzed RBCs rheological properties associated with membrane fluidity and lipid peroxidation in presence of As and quercetin (Qc). From our results we can conclude that RBCs treatment with Qc is efficient to prevent the impairment of the mechanical properties of the cell membrane produced by the As, through oxygen reactive agents in the membrane structure, mainly on the lipids. This protective effect is observed in the preservation of the erythrocytes rheological properties and consequently in the maintenance of an appropriate blood flow, specially in the small vessels in the peripheral circulation.

Arsenic intoxication, a hemorheologic view.

Arsenic (As) is a toxic semi-metal of wide distribution in nature. People living in regions where drinking water contains large quantities of arsenic, have an unusually high likelihood of developing blood-vessel diseases, but little is known about the mechanisms involved, i.e. the blood rheologic alterations that would contribute to the circulatory obstruction. Erythrocytes are the main target cells for arsenic compounds systemically absorbed and their cell membrane is the first place against the toxic. In this paper we have examined the in vitro effect of arsenic (As(V)) on the rheologic properties of human erythrocytes in relation with membrane fluidity and internal microviscosity. According to our present results, As(V) treatment produces oxidative degradation of membrane lipids and alteration of internal microviscosity. These red blood cells (RBCs) membrane and cytoplasmic structural damage consequently alters RBCs rheologic properties: an alteration of the RBCs discoid shape to stomatocytes, a diminution of erythrocyte deformability and an enhancement of osmotic fragility and cell aggregability. These effects impaired blood fluid behaviour that contribute to obstruct peripheral circulation and provides anemia, both clinic evidences typical of arsenic cronic intoxication.

Effect of hormone replacement therapy upon haemorheological variables.

It is already admitted that hormone replacement therapy (HRT) decreases the risk of developing cardiovascular disease, although its mechanism is not clear yet. In the present work, the effect of the HRT upon cellular and plasmatic haemorheological factors determining blood flow properties: blood viscosity, plasma viscosity, plasma fibrinogen, rigidity erythrocyte index and erythrocyte aggregation rate was studied. Menopausal women were followed through a whole year of HTR. Results demonstrate that after six months of treatment there is a diminution in relative blood viscosity and erythrocyte rigidity, with constant values along the second semester. Erythrocyte aggregation, plasmatic and blood viscosity diminution observed during the treatment can be explained by the simultaneous plasma fibrinogen decrease. Modified cellular and plasmatic rheology could produce beneficial effects on blood flow, particularly in microcirculation, presenting a possible mechanism by which HTR decreases the risk of cardiovascular disease development during menopause.