Ethanol dosage regimes in studies of ethanol toxicity: influence of nutrition and surgical interventions.

In this review we consider some of the practical facets of acute and chronic drug regimes. In particular, we illustrate our arguments with specific reference to alcohol and draw attention to methodological constraints that might alter biochemical or physiological processes. These includes the imposition of nutritional abnormalities and surgical procedures. These two areas are highlighted because there is evidence to show that they have marked influences on metabolic parameters, exemplified by tissue protein synthesis. In general, there is no controversy as to methods for acute studies with alcohol, although some reports have failed to investigate whether intravenous, intragastric or intraperitoneal regimes more accurately mimic the clinical situation. With regard to chronic feeding regimes, evidence is provided to support the argument that, currently, the most appropriate feeding protocol ensures that both control and treated groups receive identical amounts of nutrients albeit with differences in the calories apportioned to ethanol, which is substituted by isocaloric glucose or other carbohydrates in controls. However, there are still other methods being employed: these are subject to misinterpretation as the principle of ensuring that control and ethanol-fed rats receive identical amounts of nutrients, is ignored. In this review we also draw attention to the fact that surgical procedures, which are often employed to facilitate the measurement of body parameters (for example, implantation of cannulae), themselves alter tissue metabolism. The importance of this relates to the concept of metabolic superimposition, which implicates interacting responses when two or more stresses (i.e. surgery and drug administration) are superimposed.