The Brain and Heart Muscle Tissue Hydration Sensitivity to Painless and Painful Hot Plate Heating of Rats

Previously, it was hypothesized that the over-hydration of excitable cells leading to the abnormal excitation of the membrane, which transmits the nerve signal to the central neuronal system, can generate pain sensation. To check this hypothesis by means of painless and painful heating of experimental animals with “hot plate” method the hydration sensitivity of several body areas to pain was studied. For this purpose, the effect of painless (38 ̊C) and painful (52.2 ̊C) heating on rats’ heart muscle, brain cortex and cerebellum tissue hydration was investigated in different experimental media (10-4M and 10-9M ouabain containing physiological solution) by means of “hot plate” method. The obtained data allow us to conclude the following: the hydrations of heart muscle, brain cortex and cerebellum tissues have different sensitivities to painful and painless heating, the hydration sensitivity of heart muscle tissue could serve as a primary marker for heating and the hydration of cerebellum tissue could serve as a marker for heating-induced pain threshold. Both painful and painless heating lead to the elevation of tissue hydration and their difference is suggested as a marker for pain sensation. Thus, the hydration is an extra-sensitive marker for pain sensation.

Keywords: Cell hydration; Hot plate; Lactate Na+/K+-ATPasa; Camp; Na+/Ca²⁺ exchange; Painless and painful heating