Renal blood flow autoregulation in developing swine

Abstract

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 The left renal artery in 38 of these animals was then cannulated for in situ perfusion of the kidney with blood withdrawn from a carotid artery by a Masterflex pump.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.

Endothelium-Derived Nitric Oxide Modulates Renal Hemodynamics in the Developing Piglet

“…At birth, the newborn has a lower renal blood flow and higher renal vascular resistance than the adult (1-4,6). The maturational pattern of renal hemodynamics involves the synchronous increase in renal blood flow and decrease in renal vascular resistance with age (1,2,(4)(5)(6)(7). In these experiments, the developing piglet exhibited a lower basal renal blood flow and higher basal renal vascular resistance, consistent with the hemodynamic patterns described in piglets (1, 4).…”

“…(Pediatr Res 34: 750-754, 1993) Abbreviations EDNO, endothelium-derived nitric oxide MAP, mean arterial pressure GNAME, N-nitro-L-arginine methylester gkw, grams kidney weight counterpart (1-6). The maturation of renal hemodynamics with age in the developing mammal involves the synchronous increase in renal blood flow and decrease in renal vascular resistance (1,2,(4)(5)(6)(7). The most rapid increases in renal blood flow occur in the first few weeks of life.…”

Cardiovascular and Renal Effects of Isoproterenol Infusions in Young Swine

“…Following a control inulin clearance period in 9 other intact swine, the left kidney was prepared for in situ perfusion [3] as follows. The right carotid artery was cannulated and heparin was administered i.v.…”

“…During the first postnatal month, responses to neural stimulation [1] and to single intra venous (i.v.) injections of catecholamines [1,2], and the appearance of renal blood flow (RBF) autoregulation [3] have been found to be maturing asynchronously. The effects of continuous infusions of cardiotonic doses of norepinephrine and dopamine on glomerular filtration rate (GFR) in the developing kid ney have also been examined [4], This report deals with the effects of another clinically useful catecholamine, isoproterenol (ISP), on the developing kidney.…”

“…infusions in kidneys perfused in situ, because ISP has well-known cardiovascular actions that could affect kidney function [11][12][13][14]. To enable us to evaluate the direct effects of ISP on the kidney, we used the standard methodology for controlled perfusion of the kidney in situ [15,16] adapted for the developing animal [3].…”