Chronic Changes of Hematocrit Value Alter Blood Pressure and Glomerular Filtration in Spontaneously Hypertensive Rats

Many studies in hypertensive humans and animals have shown that increased blood viscosity is in direct relation with essential hypertension. The aim of our studies was to investigate the effects of chronic hematocrit value changes on arterial blood pressure and kidney function in genetically induced hypertension. To this end, we studied the effects of several interventions, designed to increase/decrease hematocrit, on hemodynamic parameters, vascular reactivity, glomerular filtration and renal function curve in spontaneously hypertensive rats (SHR). Results of our study show that chronic hematocrit value elevation increases blood pressure and peripheral vascular resistance in SHR. On the other hand, chronic hematocrit lowering elucidates blood pressure and peripheral vascular resistance decrease followed by cardiac output rising. Both hematocrit value changes significantly reduce vasodilatory vascular response. Hematocrit lowering induces acute renal failure. Sodium excretion is shifted to higher blood pressure values in high hematocrit value animals and opposite - lower blood pressure values in low hematocrit value animals. Repeated transfusions develop salt sensitive malignant hypertension in SHR. Further studies are necessary to evaluate the degree of kidney damage after chronic hematocrit value changes in SHR.