Studies on the mechanism of shock. The effect of catecholamines on the temperature response to injury in the rat.

The effects of adrenaline, noradrenaline, -isoprenaline and dichloroisoprenaline (DCI) on the temperature, O consumption, heat loss from the tail, blood pressure and non-esterified fatty acid (NEFA) concentrations in the plasma of 20° and 3° acclimated rats subjected to 4 hr. bilateral hind-limb ischaemia have been investigated. In 3° acclimated rats the temperature changes in the interscapular brown adipose tissue under these conditions were also studied. The catecholamines and DCI increased heat production in the injured rats, particularly in those previously acclimated to 3°. Among the catecholamines tested -isoprenaline was the most effective and adrenaline the least. The order of their effectiveness was the same as that for their action on the plasma NEFA concentration in the injured rats. DCI also increased the plasma NEFA concentration whereas a related compound DCB, which did not raise the temperature, had no lipolytic effect. The increase in heat production caused by these compounds had no survival value for the injured rats. The possible mechanisms of these effects are discussed and it is hoped that these compounds will prove useful in the investigation of the mechanism of the decrease in heat production following injury.