Blood flow in rat sciatic nerve during hypotension.

Laser Doppler flowmetry was utilized to examine blood flow in sciatic nerves of barbiturate-anesthetized and of unanesthetized decerebrate rats, in response to hypotension induced by graded exsanguination or by graded clamping of the descending aorta. Continuous laser Doppler flowmetry signals decreased linearly with decreasing arterial blood pressure. In anesthetized as well as in unanesthetized rats, the signal approached zero at a systemic blood pressure of 14 mm Hg or less. The results do not demonstrate autoregulation of blood flow in the rat sciatic nerve during systemic hypotension.