THE INFLUENCE OF CHLORPROMAZINE ON PHYSICAL AND CHEMICAL MECHANISMS OF TEMPERATURE REGULATION IN THE RAT

¹ Department of Physiology, Indiana University Medical Center, and Department of Anatomy and Physiology, Indiana University, Bloomington, Indiana

The effects of chlorpromnazine on chemical and physical mechanisms of temperature regulation in the rat have been investigated at different environmental temperatures. Administration of 25 mg/kg to animals in a cool environment of 23°C resulted in a decreased oxygen consumption, an increased tail temperature, an increased tail blood flow, loss of piloerection and loss of shivering. At a low dose, 6.25 mg/kg, body cooling was one-half that of the high dose without a concomitant decrease in oxygen consumption. Body cooling with 10% oxygen was less than that obtained with the low dose of chlorpromazine. However, oxygen consumption was similar; and shivering was observed at the low dose. Decreased survival time of chlorpromazine-treated animals exposed to a hot environment is due to an alteration in physical mechanisms resulting in a decreased ability to dissipate body heat as evidenced by a reduction in tail blood flow and decreased salivation. The decreased peripheral blood flow was due to a lack of vasodilation, not to a decrease in blood pressure. Chlorpromazine abolished all mechanisms of temperature regulation for both heat and cold.

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