Intra-articular knee joint temperature variations in response to cooling and heating of the skin in the cat.

Abstract

AbstractThe intra‐articular temperature was measured in the knee joint of the cat during cooling and heating of the anteriomedial aspect of the thigh. Cooling produced a transient increase of the intra‐articular temperature before it began to fall, and rewarming gave a transient increased fall of the intra‐articular temperature before it began to rise. These paradoxical phenomena could be produced in the intact animals and in animals with partially denervated knee joints. In a flayed limb no paradoxical temperature phenomena could be produced, neither could they be set up in a limb deprived of its sympathetic outflow by unilateral lumbar sympathectomy. The blood pressure was found to increase and decrease transiently during cooling and heating respectively. The variations of the pressure occurred almost simultaneously with the paradoxical temperature phenomena in the joint. These blood pressure variations can, however, only be part of the explanation of the paradoxical effects seen, because cooling the intact limb which increases the blood pressure, was not found to produce the phenomenon in the contralateral sympathectomized side. The mechanisms behind the paradoxical phenomena are discussed and it is concluded that temperature variations as measure of bloodflow variations in response to cooling and heating can only be used when they vary in the opposite direction to the stimuli applied.