Physical effects of increased venous and extrarenal pressure on renal vascular resistance.

AN understanding of the purely hydraulic relationships which affect the relation of pressure to flow in the complex renal vasculature is a needed background for differentiating vasomotor changes with elevated venous renal pressureand effects of extrarenal pressure. I t has not been determined, for example, whether increased venous pressure passively lowers or increases renal resistance. Venous distention within the relatively inextensible renal capsule might raise the total resistance of the kidney by increasing the interstitial pressure and effectively narrowing the high resistance intrarenal vessels. The reasons why the question can not be resolved by perfusion of the kidney with blood or saline have been discussed in the preceding paper.