1. Renal function was measured in seven normo thermic (38°C) and seven hypothermic (27°C) dogs.
2. The glomerular filtration rate was 60% lower in the hypothermic animals, and the renal blood flow was 51% lower. The intrarenal distribution of blood flow was measured by the uptake of 86Rb from the blood into different regions of the kidney. Hypothermia reduced flow by 34% in the outer cortex, 72% in the inner cortex, 61 % in the outer medulla and 69% in the inner medulla.
3. Radioautography indicated a high blood flow to an area of the outer medulla of hypothermic kidneys, which may indicate medullary blood flow ‘shunting’.
4. The results have been discussed in relation to a number of clinical and experimental observations.