Application of external negative pressure to the extremities in man allows measurement of myogenic vascular reactions.

Transmission to tissue of externally applied negative pressure (10-100 mmHg) was studied in male volunteers in the upper arm. When the negative pressure was applied there was a rapid decline in tissue pressure and when the negative pressure stopped tissue pressure recovered rapidly. Negative pressure was transmitted fully or almost fully to the entire anterior and posterior tissue compartments, regardless of tissue depth and of the magnitude of the negative pressure applied. Regional venous pressure decreased as the negative pressure was applied but soon returned to the control level. Arterial pressure and the heart rate were unaffected. These findings indicate that external negative pressure can be used to produce graded and defined alterations in vascular transmural pressure in all parts of the exposed tissue, with few passive flow changes and without interference to systemic reflexes. External negative pressure may therefore represent the most convenient method for investigation of the stimulus-effector response characteristics of myogenic reactions in different consecutive sections of the vasculature.