SUAMARYThe timed uptake of 13II-labelled human serum albumin was used as an index of regional perfusion in the isolated rat kidney.1. Arginine vasopressin in doses of 1, 5 and 10 ,uu./ml. of perfusate decreased papillary perfusion. Total renal perfusion was decreased only by the 5 Itu. dose.2. Ornithine-8-vasopressin in doses of 5 and 10 ,u./ml. of perfusate decreased papillary perfusion. Total renal perfusion was decreased only by the IO ,uu. dose.3. When the relative viscosity of the perfusate was increased to a value of 2'0 from the control value of 1.7, both papillary perfusion and total renal perfusion were reduced.4. Arginine vasopressin further reduced papillary flow in kidneys perfused with high viscosity artificial plasma.
1. The effect of angiotensin II-amide upon the intrarenal distribution of perfusate was studied in the isolated rat kidney.
2. Low concentrations of angiotensin, 4·86 pmol/l (0·005 μg/l), reduced the flow rate through the papilla but did not alter total flow.
3. Higher concentrations of angiotensin, 0·486 nmol/l (0·5 μg/l), reduced total renal flow but did not decrease papillary perfusion.
4. In these experiments the perfusion pressure was maintained constant, indicating that the changes in flow were due to a direct effect of angiotensin upon the renal vasculature.
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