AJP - Heart and Circulatory Physiology, Vol 245, Issue 1 1-H6, Copyright © 1983 by American Physiological Society
Renal blood flow autoregulation in developing swine
N. M. Buckley, P. Brazeau and I. D. Frasier
Pressure-flow relationships (P/F) in the renal circulation were determined
in 62 swine, aged 1 day-2 mo, anesthetized with pentobarbital sodium.
Aortic and inferior vena caval pressures and renal and femoral arterial
flows were recorded. Blood gas composition and pH and body temperature were
monitored. The P/F was first determined while perfusion pressure was
decreased for 2 min at each pressure by suprarenal aortic occlusion. The
left renal artery in 38 of these animals was then cannulated for in situ
perfusion of the kidney with blood withdrawn from a carotid artery by a
Masterflex pump. The P/F was subsequently determined by changing pump flow
for 2 min at each flow while recording perfusion pressure. Records were
analyzed for transient and steady-state effects. Readjustments in renal
vascular resistance (RVR) were apparent within 5 s after changing pressure
or flow. The RVR stabilized at a new level within 2 min. Graphs of
steady-state data delineated an autoregulatory range in the P/F for animals
as young as 2 wk of age. We conclude that renal blood flow autoregulation
in this mammal is negligible at birth and develops progressively during the
first postnatal month.
