THE VENOARTERIOLAR RESPONSE OF THE SKIN IN HEALTHY LEGS MEASURED AT DIFFERENT DEPTHS

The venoarteriolar response (VAR) of the skin in healthy legs of 20 su bjects was investigated. The laser Doppler flux (LDF), at an experimen tal venous hypertension of 30 mmHg, 45 mmHg and 60 mmHg, produced by a pneumatic cuff around the thigh in a recumbent position, was compared with the LDF in a sitting position. The LDF of the skin was measured simultaneously at the same site of the superficial capillary layer (wi th 543 nm) and of the deeper capillary layer (with 780 nm). At 543 nm the LDF did not differ significantly at any cuff pressure from the LDF recorded in a sitting position, whereas at 780 nm the LDF was signifi cantly higher at the cuff pressure of 30 mmHg than the LDF in a sittin g position (P = 0.002). The VAR was much weaker at 543 nm than at 780 nm, and the scatter of the VAR values was high. In a sitting position the VAR at 543 nm was 9.3% and at 780 nm 34.6% (P < 0.001). The VAR at 543 nm at the cuff pressure of 30 mmHg did not differ significantly f rom the VAR caused by the sitting position, whereas at 780 nm the VAR at the cuff pressure of 30 mmHg was significantly less than the VAR ca used by the sitting position (P = 0.001). Despite the high scatter of the VAR values, these findings suggest that the VAR in the superficial capillary layer is smaller, and that it reached maximum at lower veno us hypertension, than the VAR in the deeper capillary layer.