Change in responses of skin receptors to repeated heat stimulation

In experiments with cats, study was made of the period of increase in afferent activity during repeated heat stimulation (up to 48°C) of the skin; parallel recordings were made of skin tonus. With each application of heat, skin tonus decreased. Meanwhile, when skin temperature approached normal (30°), the skin again contracted, but tonus was not completely restored with subsequent heating (3 min pause). Repeated heating resulted in loss of tonus. At the same time, the period in which afferent activity developed decreased. These two processes are parallel, which leads to the conclusion that they are related.