The control of shivering in the rat

Abstract

1. 1. The control of shivering was investigated in conscious laboratory rats by quantitatively measuring the electromyographic response to defined thermal stimuli. 2. 2. Animals were exposed to changes in ambient temperature of (a) less than 0.05°C · min −1; (b) 0.23–0.30°C · min −1; (c) 1.33–2.00°C · min −1; and (d) 10.83°C · min i−1between set limits. 3. 3. At the slowest rate of ambient temperature change (less than 0.05dgC · min −1) rats were able to maintain colonic temperature within reasonably narrow limits. There was a reciprocal relationship between integrated EMG and ambient temperature. 4. 4. At a rate of change of ambient temperature of 0.23–0.30°C · min −1, there was a reciprocal relationship between integrated EMG and ambient temperature but colonic temperature varied more widely than in 3, above. 5. 5. The reciprocal relationship between ambient temperature and integrated EMG was maintained when ambient temperature changed at a rate of 1.33–2.00°C · min −1; colonic and hypothalamic temperatures varied with ambient temperature in a damped fashion. 6. 6. When almost square wave changes in ambient temperature of 10.83°C · min −1 were imposed, colonic or hypothalamic temperatures were unaltered, but shivering could be immediately initiated or inhibited. 7. 7. It is concluded that temperature input from the skin is very important in the onset and offset of shivering.