Blood flow measurement during exercise in sheep using Doppler ultrasonic method

Continuous recording of blood flow to the coronary, renal and hindlimb vascular beds of sheep has been carried out using flow probes implanted around the major vessels supplying these regions. Blood flow has been recorded at rest, with the sheep running at speeds of 1–16 kmh⁻¹ on a treadmill, and during the recovery period. A Doppler flowmeter has been developed to facilitate compatibility with existing equipment, to enable reliable reproduction of the unit and to keep costs to a minimum. To minimize interference accompanying the violent movements of exercise great care must be taken with the electrical connections and flow probes require streamlining to facilitate implantation. Blood flow to both hindlimb and coronary vascular beds increased during exercise while that to the renal vascular bed did not change. Thus continuous recording with the Doppler ultrasonic flowmeter can be utilised during all phases of exercise, unlike other methods such as the use of radioactive microspheres which provides only point estimations and has limited application for repeated measurement.