Abstract
It is well documented, both in humans and animals, that low rates of glomerular filtration prevail during early postnatal life. Although several explanations for this phenomenon have been offered, no direct measurements of the forces responsible for glomerular filtration in the developing animal are available. This information was sought in the present study by micro-puncture techniques. Free flow proximal intratubular pressure (Pf), “stop flow” (Ps), mean arterial, and colloid-osmotic pressure of the plasma protein (Pco), were determined in guinea pigs ranging in age from 1 to 56 days (27 animals). The values obtained were used in the calculation of glomerular capillary pressure, Pcap = Ps + Pco, and of the effective filtration pressure, Pcff = Pcap — (Pf + Pco). Free flow intratubular pressure increased from 5.5 ± 0.3 during the 1st to 9.2 ± 0.2 (mean ± S. E.) during the 8th week of life, whereas capillary pressure increased from 21.2 ± 1.8 to 29.3 ± 1.0 mm Hg. Since the actual increase in capillary pressure was about twice the increase in intratubular pressure, effective filtration pressure rose accordingly from 4.9 ± 0.4 to 9.4 ± 0.8 mm Hg. During the same period mean arterial pressure changed from 42.9 ± 2.2 to 58.5 ± 7.9 mm Hg. It appears, therefore, that an increase in glomerular capillary pressure is an important factor in the increase in glomerular filtration rate that is observed with age.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Spitzer, A., Edelmann, C. Pressure gradients for filtration in the developing kidney. Pediatr Res 5, 382 (1971). https://doi.org/10.1203/00006450-197108000-00049
Issue Date:
DOI: https://doi.org/10.1203/00006450-197108000-00049