Optical spectroscopy and cerebral vascular effects of alcohol in the intact brain: effects on tissue deoxyhemoglobin, blood content, and reduced cytochrome oxidase

Alcohol Clin Exp Res. 1993 Dec;17(6):1319-24. doi: 10.1111/j.1530-0277.1993.tb05248.x.

Abstract

Dose-response effects of acute ethanol infusions were studied, noninvasively, in the unopened brain to examine the hypothesis that ethanol can induce stroke-like events as a consequence of cerebral vasospasm and tissue ischemia. By using a single sending and receiving fiber, an optical backscatter measurement (500-800 nm) was used to monitor the levels of deoxyhemoglobin (DH), reduced cytochrome oxidase (rCO), and relative tissue blood content in a closed cranium preparation. Anesthetized rats were prepared by cannulating a branch of the internal carotid artery and subjected to either bolus infusions (1.25 or 2.5 microM ethanol in Ringers/g tissue) or to constant infusions of 5 or 10% ethanol at various rates (0.30-2.92 microM/g/min). To facilitate optical penetration, a portion of the left parietal cranium was shaved to a translucent appearance. Results showed that low, bolus doses of ethanol typically produced a slight increase (5-10%) in the oxyhemoglobin signal, indicating that vasodilation had probably occurred. Higher doses, however, produced a prompt and significant reduction in the hemoglobin signal, increased levels of DH, and a rise in rCO suggesting a vasoconstrictor response leading to ischemia had occurred, followed by recovery within 3-5 min. Constant infusions of ethanol produced a similar cerebral vascular response, in a dose-related manner, but of a more sustained nature. At levels of 50-60% of the maximum bolus dose, the effect was more pronounced, accompanied by an increase in the levels of rCO (by 50-90%). Control experiments using identical volumes/flow rates of Ringers solution produced no significant alterations in the optical spectrum.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alcoholic Intoxication / physiopathology*
  • Animals
  • Blood Volume / drug effects*
  • Blood Volume / physiology
  • Brain / blood supply*
  • Cerebrovascular Disorders / physiopathology
  • Dose-Response Relationship, Drug
  • Electron Transport Complex IV / metabolism*
  • Ethanol / toxicity
  • Hemoglobins / metabolism*
  • Male
  • Oxidation-Reduction
  • Rats
  • Rats, Wistar
  • Regional Blood Flow / physiology

Substances

  • Hemoglobins
  • Ethanol
  • deoxyhemoglobin
  • Electron Transport Complex IV