Aging on Hematocrit and Blood Viscosity

Abstract

The purpose of this study was to determine the aging effects on hematocrit and blood viscosity in rats. Old (22~25 months), middle (mid)-aged (15~17 months), adult (6~7 months), and young (3 months) male and female rats of the Sprague-Dawley strain were studied. Blood was collected by heart puncture in rats under ether anesthesia. The hematocrit was determined by a microhematocrit centrifuge. The viscosity of whole blood was measured at various shear rates at 37℃ by means of a Mooney-Ewart viscometer. The levels of hematocrit(%) were 43.25±2.82, 43.64±1.14, 45.09±2.55, and 42.08±2.63 for young, adult, mid-aged and old male rats respectively. The levels of hematocrit were 43.56±1.24, 45.74±3.94, 42±1.25, and 43.57±1.25 for young, adult, mid-aged and old female rats respectively. The levels of blood viscosity centipoises were 11.62±1.00, 8.15±0.64, 6.52±0.46, 5.32±0.36 and 4.36±0.27 for young male rats at shear rate of 10, 25, 50, 100 and 200 S^(-1). The levels of blood viscosity were 12.67±1.3 7, 8.14±263, 6.41±0.33, 5.14±0.19, and 4.20±0.18 for old male rats at shear rate of 10, 25, 50, 100 and 200 S^(-1). The levels of blood viscosity were 11.60±1.54, 8.07±0.77, 6.45±0.54, 5.24±0.41 and 4.33±0.30 for young female rats at shear rate of 10, 25, 50, 100 and 200 S^(-1). The levels of blood viscosity were 12.15±1.14, 7.68±3.43, 6.03±3.29, 4.85±3.21 and 4.04±0.15 for old female rats at shear rate of 10, 25, 50, 100 and 200 S^(-1). The hematocrit and the blood viscosity were not altered during aging in both male and female rats. The results indicate that factors as the hematocrit, viscosity and vascular changes during aging should be considered together for the high incidence of vascular disease in the elderly.