[Significance of spontaneous and evoked temperature changes in the brain in applying the thermoclearance technic to the determination of cerebral blood flow].

The authors carried out studies on cats under urethane narcosis and found that the presence of spontaneous temperature changes in two neighbouring regions of the cerebral cortex, were discovered at a distance of 5 mm from each other in a parallel course. After administration of pharmacological agents such as papaverine, nivaline, etc. in the region of the cerebral cortex there were quick transitory temperature changes as in the two neighbouring regions of the cortex these changes had one-way course, but not a parallel one. This caused the occurrence of changes in the temperature difference between them, which was recorded by switching of the differential amplifier. These changes could be indicated as "zero reaction", having in mind the essence of the thermoclearance methods by means of which additional source of heat was introduced in one of the two regions. The real changes in the blood flow of the brain under the influence of the administered pharmacological agent represented the difference between the recorded and the so called zero reaction. The established facts oblige to take into consideration a possible presence of "zero reaction" during usage of thermoclearance method for determination of blood flow in other organs as well.