Hemodynamics of the recently opened glomeruli. Micropuncture study in 22- to 26-day-old puppies.
In 22- to 26-day-old beagle puppies, just after superficial nephrons have begun to function, the single nephron glomerular filtration rate is extremely low (6.7 nl.min-1) approximating a tenth of the adult value (57 nl.min-1) even though blood pressure is as high as 90 mm Hg. Glomerular vascular resistance is almost six times the value found in the adult dog (1.8 vs. 0.32 mm Hg.ml-1.min), this increase being mainly due to a rise in afferent (80%) rather than in efferent (20%) resistance. The glomerulus, having only recently started to function, is characterized by filtration pressure equilibrium, a phenomenon atypical of superficial glomeruli in the adult dog. These findings favor the concept that a low glomerular blood flow rate might be the main cause of the very low SNGFR in the new glomeruli, although some contribution of an altered ultrafiltration coefficient cannot be excluded.
Heller
J
J
Institute for Clinical and Experimental Medicine, Prague, Czechoslovakia.
Horácek
V
V
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D004285:Dogs; D005260:Female; D005919:Glomerular Filtration Rate; D006439:Hemodynamics; D007678:Kidney Glomerulus / Q000502:physiology*; D008297:Male; D009399:Nephrons / Q000502:physiology*; D014655:Vascular Resistance