Effects of reserpine upon thermal stress-induced cardiovascular changes.

The cardiovascular changes induced by 15% total body surface area third-degree burn have been studied in anesthetized dogs. The responses observed were a decrease in plasma volume, a decrease in cardiac output, and a slight but insignificant fall in mean arterial pressure. Graded doses of reserpine ranging from 0.1 to 1.0 mg/kg were administered preceding thermal trauma, and produced a reduction in plasma volume loss. The most effective dose of reserpine was 0.2 mg/kg. Despite the significant reduction (approximately 50%) of plasma volume loss in this dosage group, there were no significant alterations in either cardiac output or mean arterial pressure. These results demonstrate that reserpine is effective in reducing plasma volume loss but ineffective in altering the other cardiovascular parameters observed. Based upon the size of the maximally effective dose in reducing plasma volume loss and the failure of this dose to alter the other cardiovascular responses, it is postulated that the plasma loss reduction may be due to some action of reserpine other than its release of catecholamines and reduction in catecholamine stores.