RESUMEN
The effects of the gravitational potential energy change (GPEC) and the thermal stress on finger microvascular responses were studied by laser Doppler and ultrasonic Doppler flowmetry. Seven healthy male subjects, aged 21 to 31 yrs, participated in the experiment after giving their informed consent. The hand was moved upward (about 60 cm) or downward (about 55 cm) from the heart level to change the vascular transmural pressure of the finger (GPEC) . Sensors of laser Doppler and ultrasonic Doppler flowmeters were attached to the lateral side of the first finger and the skin surface over the radial artery, respectively. Experimental room temperature was maintained at 24°C. Laser Doppler flow (LDF) was decreased at an elevated and lowered arm position. The pulsatile component of LDF, evaluated by the difference between systolic and diastolic LDF, increased when the arm was elevated, but it showed no significant changes when the arm was lowered. Mean blood velocity (MBV) and diastolic blood velocity (DBV) of radial artery decreased when the arm was elevated, whereas the pulsatile blood velocity (PBV), evaluated by the difference between systolic blood velocity (SBV) and DBV, were increased. At the lowered arm position, SBV and PBV decreased significantly, but DBV showed no significant changes. The thermal stress (43°C, 10 min) increased the PBV when the arm was elevated, but the PBV diminished the decreasing rate when the arm was lowered.<BR>These results suggest that the measurements used may be useful for the analysis of arteriolar compliance and microvascular response to the change of transmural pressure pro-duced by the gravitational potential energy change.
RESUMEN
The effect of changes in vascular transmural pressure upon differential digital plethysmogram (delta DPG) was studied in seven normal subjects. Changes in vascular transmural pressure were produced by the gravitational potential energy change (GPEC method) of an extremity from the heart level. Delta DPG which was characteristic of stability, discrimination and low speed record by modified devices was applied for the experiments including postural, static and dynamic exercises. Room temperature during experiments was kept constant. The Delta DPG-P wave amplitude in maximal elevation of upper and lower extremities (mean±S. D., n) increased to 162.3±33.5% (38) and 176.7±33.4% (12), respectively, and that in maximal lowering of upper and lower extremities decreased to 36.9±10.5% (35) and 37.5±12.6% (15), respectively. These data reveal that the GPEC method may be useful for the determination of arteriolar sensitivity in humans.