[Thermometry in experimental inflammation. I. Studies on the circadian rhythm of the paw temperature in healthy rats and temperature behavior in acute inflammation after injection of kaolin, carrageenin and dextran].

Plantar paw skin temperature development was examined in 26 healthy male albino rats using Heimann's infrared thermometer KT 41. This examination was carried out on two groups of 12 and 14 male rats after intraplantar injection of kaolin, carrageenin, and dextran. Normal untreated animals showed a distinct circadian course of daily temperature, with minimal temperatures in the morning and maximal ones in the evening, and a mean difference of 3.9 degrees C. Among the phlogistic substances injected, kaolin proved to induce the most powerful increase in plantar skin temperature. It was followed by carrageenin; temperature increase in kaolin edema, however, started later than that induced by carrageenin. No pathological skin temperature increase was found after the injection of dextran. Physiological circadian temperature course, however, was modified in an undulating fashion. All phlogistic substances persistently disturbed thermoregulation in the inflamed rat paw. The comparison of temperature development in our experiments with paw swelling in similar models described in the literature did not always show a correspondence. Quantification of the intensity of experimental inflammations in animals using only a single parameter is thus not always adequate; under certain circumstances it can even lead to wrong conclusions. Nevertheless, infrared thermometry proved to be a very suitable method of estimating skin temperature as a parameter of inflammation.