Renal Responses of the Recumbent Nonhuman Primate to Total Body Water Immersion

Experiments were performed to determine the extent to which thoracic translocation of blood and abdominal compression contribute to the diuresis and natriuresis during head-out water immersion in the anesthetized nonhuman primate. Neither a diuresis nor natriuresis occurred in animals immersed in the recumbent posture to a depth such that the abdomen was subjected to the same water pressure as during head-out upright immersion. It is concluded that the abdominal compression observed during upright immersion does not contribute per se to the renal responses and that the immersion-induced translocation of blood to the thorax may be the causal factor during this volume stimulus.