A new concept of renal hemodynamics.

Observations which show that urine output can vary with changes in the contour of the pulse cure, that it can even increase while the mean blood pressure falls during counterpulsation, that the well known hypertensive effect of a renal artery stenosis can also be produced by an aneurysm of the renal artery, cannot be explained by orthodox concepts of renal hemodynamics. The anatomical fact that the afferent glomerular arteriole is about twice as large as the efferent has so far not been adequately explained. The hypothesis that the combination of pulsatile flow and the unique anatomical configuration of the glomerulus permit a hydraulic switching mechanism which modifies profoundly its perfusion explains these questions.