Chronic renal venous catheterization in fetal sheep.

To measure certain aspects of renal function it is necessary to monitor both renal arterial and venous blood. We describe a technique for chronically implanting a catheter in the renal vein of fetal lambs. Catheters have been inserted into the left renal vein in 11 fetuses at 120-125 days gestation and maintained for periods of 6-11 days (mean 8.7 +/- 2.2). We have determined that the catheter does not influence renal blood flow or alter renal morphology. We have also ascertained that the blood sampled from the renal venous catheter is not contaminated with blood from the inferior vena cava. This technique can be used to examine many aspects of renal physiology in the chronically instrumented fetal animal.