Renal intracortical blood flow distribution, function, and sodium excretion in unanesthetized dogs following vena caval ligation

Abstract

The renal function and the intrarenal blood flow of 9 dogs whose thoracic inferior vena cava had been previously ligated (caval dogs) and 9 other dogs, were studied. Following preparative surgery which included placement of a left atrial catheter, a femoral artery catheter, and bilateral ureteral catheters, the caval dogs gained an average of 2.1 kg of fluid weight, whereas the normal dogs gained no weight. Although neither the caval dogs' blood pressure (114 ± 7 vs. 120 ± 4 mm Hg) nor their inulin clearance (0.64 ± 0.06 vs. 0.79 ± 0.06 ml/min g-1 kidney weight) was significantly reduced, their estimated renal blood flow ([C(PAH)]/[1 hematocrit]) was considerably lower (2.30 ± 0.24 vs. 3.25 ± 0.15 ml/min g-1). During the clearance study, the caval dogs' excretion of sodium (79 ± 18 vs. 158 ± 17 μEq/min) and their fractional clearance of sodium (2.0 ± 0.4 vs. 3.4 ± 0.5%) were reduced. Studies with microspheres failed to demonstrate a selective decrease in blood flow. However, comparison studies of 9 other dogs (5 caval and 4 normal) demonstrated that microsphere results were less reproducible in caval dogs than they were in normal dogs. It is concluded that reduced blood flow is the only consistent alteration of renal function in this edematous animal model and that previous suggestions of altered distribution are not supported by these studies.