The collateral blood flow and hippuran clearance of the rabbit kidney after occlusion of the renal artery.

The collateral blood flow to the rabbit kidney was determined by two methods: (1) measurement of the venous flow after clamping of the renal artery and (2) Hippuran clearance of the clamped kidney. The collateral blood flow was found to be 0.012 ml/min/g kidney equivalent to 0.2% of the entire blood flow to the rabbit kidney. Compared with collateral blood flow in other mammals (as humans and dogs) with a collateral flow of 6.2% of the normal flow, the collateral blood flow in the rabbit is very modest. The cranial ureteric artery contributes more than 90% of the entire blood flow, while capsular perforants, important in other mammals, play no role in the supply of the rabbit kidney. Only 50% of the collateral blood flow passes the tubular system. Flow to the medulla calculated from Hippuran clearance was 35% greater than flow to the cortical part of the kidney. The subcapsular cortical tubuli were able to absorb Hippuran from the peritoneal fluid and surrounding tissues after the kidney was dissected free from its surroundings and all vessels severed. Absorption corresponded to an arbitrary serum flow of 0.0002 ml/min/g.