Intrarenal distribution of blood flow and cortico-medullary sodium gradient after unilateral splanchnicotomy in the dog.

1. Intrarenal distribution of blood flow and cortico-medullary sodium gradients have been studied in anaesthetized dogs, previously subjected to unilateral splanchnicotomy. Experiments were carried out on hydropoenic, normal, isotonic and hypotonic volume expanded animals.2. Polyuria and natriuresis were present under all experimental conditions after denervation.3. Denervation resulted in an increase in medullary blood flow, particularly in hydropoenic and normal dogs. In isotonic and hypotonic volume expansion, the increases in the medullary circulation were smaller despite a greater increase in urine flow and sodium excretion of the denervated side.4. Under no experimental condition did the cortico-medullary sodium gradient of denervated kidneys differ significantly from that of the intact kidneys.5. It is concluded that denervation polyuria might be attributed in part to an increase in medullary blood flow; the natriuresis, however, could not be accounted for by these circulatory changes. Other possibilities are discussed.