Trauma induced increases in plasma vasopressin and angiotensin II.

Previous investigators have shown that hypotension will cause an increase in plasma levels of both vasopressin and angiotensin II. Significant increases in peripheral resistance after thermal trauma suggested that a similar increase in plasma vasopressin and angiotensin II levels might occur under this condition. This possibility has been studied in the pentobarbital anesthetized dog. Peripheral resistance was calculated from measured cardiac output and mean arterial blood pressure. Vasopressin and angiotensin II levels were measured by radio-immunoassay. The results of this study showed that vasopressin plasma levels increase 4 to 6 fold 15 minutes after thermal trauma and remained elevated (3 to 4 fold) for at least 6 hours. Angiotensin II increased in a linear manner from 15 minutes to 6 hours post trauma. At 6 hours post trauma angiotensin II plasma levels were 4 times pretrauma levels. For the first 4 hours post trauma there was a positive correlation between the sum of vasopressin and angiotensin II plasma levels and the increase in peripheral resistance. These results suggest that the trauma induced increase in peripheral resistance is due to increases in plasma vasopressin and angiotensin II.