Comparison of capillary blood flow in the nailfold circulations of young and elderly men

Abstract

This study investigated the effects of aging on capillary dynamics in the human skin by comparison of capillary blood flow velocity (CBV), capillary diameter and volume capillary blood flow (CBF) in the looped capillaries within the dermal papillae of nailfolds in young (Y — mean age 26 yr) and elderly (E — mean age 63 yr) male subjects. Both toe and finger nailfolds were studied. Quantitative measurements were made only in vessels with relatively straight arterial and venous branches. However, qualitative comparisons were also made of the number of capillaries per field and the general structure of the capillaries. Flow velocity (CBV) was significantly lower in both the toe and finger nailfolds of the E compared to the Y subjects (P≤ 0.050). There was no significant difference in capillary diameter, therefore, volume flow (CBF) was also lower in the E subjects. Respective values of CBF in the toe nailfolds of the Y and E groups were: 1.41 × 104 u3/sec and 0.76 × 104 u3/sec (P ≤ 0.075). Corresponding values for the finger nailfolds were: 2.27 × 104 u3/sec and 1.35 × 104 u3/sec for the Y and E subjects (P ≤ 0.050). There were no significant differences in the number of capillaries per field between the groups although there was a trend towards fewer vessels in the toe nailfolds of the elderly. The elderly also had a higher percentage of tortuous vessels in their toe nailfolds compared to the Y subjects. This observation vis-a-vis a tendency towards fewer vessels in the toe nailfolds of the E subjects indicates that aging may have a more pronounced effect on total capillary flow in this region than indicated by CBF alone.