Patchy, intermittent ischemia in renal cortex during tourniquet shock in dog

Abstract

The effect of bilateral hindlimb occlusion on the distribution of renal cortical blood flow was investigated in anesthetized dogs. Local blood flow in outer cortex (OCF) and in inner cortex (ICF) was measured by 6 platinum electrodes recording hydrogen gas clearance. Renal blood flow fell unsignificantly while hematocrit (Hct) rose from 37 to 47% during the 4 h tourniquet period. After the release of the tourniquets average arterial blood pressure fell to about 75% of control, whereas OCF and ICF were proportionately reduced towards 30--40% of control. Hct increased to 58%. Patchy, intermittent ischemia in outer and inner cortex was irregularly observed after release of the tourniquets when Hct had increased markedly, as previously found during dehydration and endotoxin shock. The sudden shifts in washouts rates from single electrodes were not accompanied by corresponding variations in total renal blood flow. Heparinization of alpha-receptor blocking did not suppress the appearance of abrupt flow changes in this period. However, sudden shifts in local flow were also seen shortly after application of the tourniquets, before Hct had increased, in this phase possibly induced by an increased renal nervous tone. OCF and ICF fell to the same degree during tourniquet shock. Patchy, intermittent ischemia was observed in the renal cortex, most frequently at high Hct, but also before Hct did rise.