MUSCLE BLOOD-FLOW IN CATS - COMPARISON OF MICRODIALYSIS ETHANOL TECHNIQUE WITH DIRECT MEASUREMENT

A quantitative validation of the microdialysis ethanol technique was p erformed in cat gastrocnemius muscle. Six to eight microdialysis probe s were inserted into the isolated muscle preparation and perfused (0.5 -10.0 mu l/min) with Krebs-Henseleit buffer containing between 5 and 1 ,000 mmol/l ethanol. Skeletal muscle blood flow was held constant in t he range of 4-99 ml . 100 g(-1). min(-1) by a servo-controlled roller pump and was determined with the microdialysis ethanol technique as we ll as by timed collection of venous outflow. The ethanol concentration outflow-to-inflow ratio ([ethanol](collected) (dialysate)/[ethanol](i nfused) (perfusion) (medium)) decreased in a nonlinear fashion when mi crodialysis perfusion flow rates of 0.5 and 1.0 mu l/min were employed . However, a linear decrease was found between 4 and similar to 45 ml . 100 g(-1). min(-1) (r = -0.92 to -0.99). The lower the outflow-to-in flow ratio was at 4 ml . 100 g(-1). min(-1) (i.e., due to a low probe perfusion flow rate or a large dialysis membrane), the greater the sen sitivity of the method was. It is concluded that this nonradioactive t echnique provides a simple and valid method for determining nutritive blood flow in skeletal muscle.