Comparative pressure-length-diameter relationships of neonatal and adult rabbit ureters

Pressure-length-diameter relationships of neonatal and adult rabbit ureters were studied in vitro. The increase in diameter, in response to an intraluminal pressure load of 10, 20, and 40 g per cm2, was faster and greater in the neonate than in the adult. Incubation in norepinephrine decreased the diametral deformation of neonatal ureters but had little effect on deformation in the adult ureter. The in vitro neonatal rabbit ureter, thus, appears to be more compliant and more sensitive to norepinephrine than the adult ureter.