Abstract
Intrarenal glomerular blood flow distribution was studied in 34 newborn puppies ranging in age from 1 to 40 days using radio-labeled carbonated microspheres 15–25 μ. The technique was validated by histological sectioning, dual labeling of microspheres and multiple sectioning of the same kidney. Relative blood flow per gram tissue to juxtamedullary inner cortical (IC) and outer cortical (OC) glomeruli was determined by the ratio of microspheres trapped in the respective region. IC/OC ratios fell from 1.2 at birth to 0.25 at 14 days and remained relatively constant thereafter. There was no correlation between IC/OC ratio and PAH extraction (EPAH). EPAH remained constant at 0.50 during the first 40 days of life (adult EPAH = 0.85). IC/OC ratio declined as blood pressure rose from 30 to 70 mm Hg and remained relatively constant at blood pressures above 70 mm Hg. These results suggest that there is a marked change in intrarenal blood flow distribution during the first two weeks of life as more blood is delivered to outer cortical nephrons with maturation. The early large flow to juxtamedullary glomeruli suggests a large post-glomerular medullary flow. The lack of correlation between IC/OC ratio and EPAH suggests that the low EPAH in the newborn period is not due solely to a large medullary flow. Finally, intrarenal flow distribution maturation is closely related to blood pressure maturation.
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call