DESCRIPTION (provided by applicant): This proposal describes a 5 year training program designed to provide an environment appropriate for the PI's long-term goal to develop an independent academic career in Pediatric Critical Care. To ensure highly structured research training, she was recently accepted into the Ph.D. graduate program in the Department of Biochemistry. The overall goal of the research project is to test the hypothesis that vasodilatory shock represents a pathological extension of the physiological vasoconstrictor/vasodilatory signaling systems acting at caveolae. To accomplish this goal, the following specific aims will test the working model. Specific aim 1: Preliminary data suggest that down-regulation of contractile signaling by prior contractile receptor stimulation involves Ca2+, tyr-,and ser/thr phosphorylation-dependent events. Aim 1 will specifically define the' molecular players involved in contractile receptor-induced down-regulation of contraction, including the role that caveolae play in this process. Specific aim 2: Preliminary data suggest that inhibition of the rhoA/ROK signaling system at caveolae participates in both down-regulation produced by prior contractile receptor stimulation, and in activation of relaxant signaling systems. The data also suggest that both stimuli cause caveolar internalization. Aim 2 will test the hypothesis that down-regulation of contraction and relaxation reflect a common mechanism in which contractile signaling systems are temporary uncoupled from caveolae. Specific aim 3 will test the hypothesis that "failure" of vascular smooth muscle to contract during vasodilatory shock reflects prolonged uncoupling of contractile signaling systems from caveolae.The knowledge gained in basic cellular and molecular mechanisms causing vasodilatory shock will then be applied to a future project to specifically understand shock in the pediatric intensive care setting. The clinical significance is that caveolae may represent the final common pathway responsible for vasodilatory shock, and understanding these processes may lead to the development of novel therapeutic agents to treat shock.