The 'no-reflow' phenomenon in cerebral circulation.

Abstract

BACKGROUND: The purpose of our research was to study the pattern of post-ischemic cerebral hemodynamic changes and observe the impact of enalapril on the course of these changes in cats. MATERIAL/ METHODS: The experiments were carried out on anesthetized cats using the autohemoperfusion method in cerebral and peripheral vessels with a stable volume of blood. Transitional peripheral (lower limb) and brain ischemia was simulated by stopping the autohemoperfusion pump for 15 minutes, tying various anastomoses in the neck region, and reducing arterial blood pressure (ABP) to 40-30 mm Hg, followed by reinfusion of the shed blood. RESULTS: Intravenous administration of enalapril solution in a dosage of 0.25 mg kg-1 in the early phase of reperfusion (10 minutes into the postischaemic period) prevented the development of long-term "no-reflow"of cerebral blood flow, as observed in the controls. There was a 40.8+/-3.2% reduction of cerebrovascular tone, 39.3+/-3.1% in peripheral vessels, and 44.7+/-1.5% lower arterial blood pressure at the end of 120 minutes. CONCLUSIONS: Enalapril caused a reduction of cerebrovascular tone, completely eliminating the "no-reflow" syndrome after brain ischemia and somewhat potentiated the hyperperfusion phase. At the same time, the drug did not aggravate the general hypotension observed after ischemia in the controls.