The effect of haemorrhage on renal blood flow and intrarenal flow distribution.

Bleeding of dogs to constant arterial pressure of 90 mm/g and 60 mmHg respectively decreased renal blood flow in proportion to pressure reduction. There was no evidence of autoregulation of renal blood flow or of selective renal vasoconstriction. With the radioactive microsphere technique a moderate shift of blood flow from the outer to the inner cortex was observed. In the renal 133Xe wash-out curves exponent 1(attributed to the elimination of the indicator from the cortex) was more reduced than exponents 2 and 3 (medulla). These findings may not indicate a redistribution of renal blood flow through resistance changes in specific parts of the renal vasculature but may represent the consequences of focal cortical ischaemia, most prominent in the outer cortex.