Activation of the sympathetic nervous system plays a pivotal role in the response of an organism to stress. This activation and the resultant cardiovascular adjustments in large part determine the organism's chances for survival. Studies of sympathetic efferent discharge, plasma catacholamines, and cardiovascular function have documented this increase in activity. Recently, a potent system for modulation of sympathetic activity by endogenous opioid peptides has been described. In the conscious, intact animal, this system is apparently involved with limiting sympathetic activation during stress. Although this system may function in a variety of stressful situations, the work of Dr. James Schadt will focus on its role in hemorrhagichypotension. This work will be performed on rabbits and will use neurochemical measures to determine blood levels of essential peptides during stress and correlate these with sympathetic nervous system activity. This work is important in understanding the biological basis of stress.
