Laboratory Techniques for Heating Experimental Animals

Abstract

A general requirement for experimental hyperthermia studies involving laboratory animals is that it should be possible to express results in a quantitative manner. Thus, temperature distributions must be known. Furthermore, to simplify interpretation of results, uniform temperature distributions are desirable. A common and apparently simple method of heating experimental animals is by immersion in water in a temperature controlled bath. In some cases this method is indeed satisfactory in that the tissue under investigation is heated uniformly to a temperature within 0.1°C of that of the bath; the experiments of Law (1981) involving mouse pinna are examples. In other cases the effects of blood flow have been shown to lead to non-uniform temperatures and heterogeneous response. For example, Merino et al (1978) and Hume et al (1979) found that water bath heating of exteriorised intestine of mouse produced a non-uniform response with the smallest effect in regions adjacent to the mesenteric blood vessels, presumably due to local cooling. Hume et al measured temperatures in the intestine either ‘near to’ (within 0.5 mm of the mesenteric attachment) or ‘far from’ (diametrically opposite to the mesentery) and found that whilst steady state temperatures far from the vessels were typically 0.1-0.2°C below the temperature of the bath, those near to the vessels were as much as 2°C below bath temperature.