Prostaglandin E2, found in high concentrations in the kidney, restores to normal the attenuated reflex release of epinephrine seen in acutely anephric dogs following hemorrhage. In many effector systems PGF2 alpha and PGE2 have roughly opposing actions. The influence of PGF2 alpha on the attenuated reflex epinephrine release of the anesthetized anephric dog is not known. We plan to study the effect of intravenous PGF2 alpha, 1 mcg/kg/min., on the release of epinephrine, norepinephrine and Dopamine into adrenal vein-femoral shunts. True adrenal secretion rates of these three catecholamines will be determined in anesthetized dogs by subtracting arterial plasma catecholamine content, measured by a single isotope radioenzymatic method, from adrenal venous catecholamine content and relating these catecholamine gradients to adrenal flow measured directly from adrenal venous sampling time. Simultaneous aortic and adrenal vein samples will be drawn just prior to hemmorrhage and 15, 30 and 60 minutes thereafter. Two groups, 5-10 dogs each, of acutely anephric animals will receive PGF2 alpha infusion, one group will be studied at rest and the other following hemorrhage to a mean arterial pressure of 50 mm Hg. The two groups will be compared statistically and will be compared to groups of control animals described below. As appropriate controls for the above groups and also the necessary background data for the radio-enzymatic technique for catecholamines in anesthetized dogs, four groups of anesthetized dogs 5-10 dogs each will be studied. One group with intact kidneys at rest, the second group with acute nephrectomy at rest, a third group with intact kidneys and hemorrhage and the fourth group with acute nephrectomy plus hemorrhage. Appropriate intergroup statistical comparisons will be made between these animals and to the PGF2 alpha treated groups.