Electromagnetic determination of portal venous flow in rats during exercise

We investigated the response of portal venous blood flow in rats to different exercise intensities by long term implantation of an electromagnetic flowprobe around the portal vein. The coefficients of variation for five determinations of portal venous flow for 5 consecutive days before exercise were 9.7 ± 2.0%. The portal venous flow and oxygen consumption (V̇O₂) were simultaneously measured during and after treadmill exercise of five intensities (5–25 m/min). Portal venous flow remained unchanged at the moderate exercise levels of 5, 10 and 15 m/min at a 15% grade for 20 min. The portal flow demonstrated a significant decrease at the 20 m/min with a 60 ml/kg/min of V̇O₂, but the decreased portal venous flow returned to the pre-exercise level during the recovery period. At the highest intensity of exercise, 25 m/min, the decreased portal venous flow remained unchanged throughout the recovery period. We concluded that the continuous measurement of portal venous flow during exercise offers a clear advantage over other methods, and that there was an evoking point during the high intensity exercise though portal venous flow was unaltered at a moderate intensity of exercise.