Regional brain blood flow in the conscious gerbil

Regional brain blood flow was determined in 23 awake, unparalyzed gerbils with a simplified indicator-fractionation technique. The use of intravenous 14C-butanol, an indicator that is freely diffusible into the brain, eliminated the need for repetitive sampling of arterial and cerebral venous blood and reduced the period of indicator circulation of 10 seconds. Gerbils spontaneously breathing room air (PaCO2 = 32 +/- 1 (SE) mm Hg) had blood flows in whole cerebrum, cerebellum, and brainstem of 102 +/- 4, 93 +/- 5, and 114 +/- 6 ml/100 gm/min respectively. Cerebral blood flow increased linearly with elevations in PaCO2 (r=0.969) and averaged 3.14 +/- 0.17 ml/100gm/min per mm Hg increase in PaCO2. Interpolated cerebral blood flow at a PaCO2 of 40 mm Hg was 127 +/- 2 ml/100 gm/min. This technique is easy and convenient to use, involves no intracranial surgery, requires steady state conditions for only 10 seconds, and minimizes blood loss in small animals. In more discrete brain regions a less volatile indicator is needed.