EFFECTS OF SUBCUTANEOUS INSULIN-LIKE GROWTH-FACTOR-I INFUSION ON SKINMICROCIRCULATION

When healthy volunteers were treated with human insulin-like growth fa ctor-I (IGF-I), mild generalized edema often developed. In the present study, the effect of IGF-I on cutaneous capillary permeability and mi crovascular skin blood flow was investigated using fluorescence videom icroscopy and laser Doppler fluxmetry. Transcapillary diffusion of int ravenously injected sodium fluorescein (NaF) was quantitated by videod ensitometry in terms of fluorescent light intensities (FLIs) 5, 10, 20 , 30, 60, 120, 180 and 300 s after the first appearance of the dye. La ser Doppler fluxmetry was performed at rest (LDF(rest)) and during pos tocclusive reactive hyperemia (LDF(peak)). Eight healthy subjects (3 w omen, 5 men; mean age 28 years, range 24-30 years) were investigated. The sensing site was the skin on the right dorsal wrist. Measurements were performed after 4 days of subcutaneous infusion of 0.9% saline (c ontrol) and of IGF-I. Mean values for the FLI were significantly highe r after IGF-I than after saline infusion (p < 0.05), when the FLIs wer e expressed in arbitrary units. As percentages of their individual max ima, the differences were significant (p = 0.05) after 60 s (23.6 +/- 6.6% with NaCl and 31.9 +/- 7.6% with IGF-I). LDF(rest) and LDF(peak) tended to be higher after IGF-I treatment without achieving statistica l significance (p = 0.176). The mean appearance time of the dye after injection was significantly shorter (p = 0.016) in the IGF-I group tha n in the control group (32.0 +/- 8.4 s with IGF-I, 42.4 +/- 8.3 s with NaCl). In conclusion, IGF-I does not increase skin blood flow, but si gnificantly increases transcapillary diffusion of NaF. Both mechanisms may be responsible for the development of edema.