Journal of Applied Physiology, Vol 66, Issue 1 79-87, Copyright © 1989 by American Physiological Society

ARTICLES

Distribution of pulmonary vascular pressure as a function of perinatal age in lambs

M. L. Tod and J. T. Sylvester
Department of Medicine, Johns Hopkins Medical Institution Francis Scott Key Medical Center, Baltimore, Maryland 21224.

The distribution of pulmonary vascular resistance (PVR) with respect to compliance was determined using vascular occlusion in isolated lungs from lambs at five ages, from 2 wk before birth to 1 mo of age. The major change in PVR occurred in the pressure gradient across the middle compliant region (delta Pm), which dropped sharply at birth, remained low for 2 wk, and increased at 1 mo. Pulmonary vasoreactivity also varied with ages. Lungs at 0-4 days did not respond to hypoxia and responded poorly to prostaglandin F2 alpha (PGF2 alpha). In contrast, lungs at 13-33 days had significant increases in delta Pm and the gradient across relatively indistensible arterial vessels during hypoxia and increases in all gradients with PGF2 alpha. Ventilation of fetal lungs reduced PVR, mainly because of a 50% reduction in delta Pm. Our results demonstrate that the magnitude and distribution of PVR relative to compliance varied as a function of perinatal age and that pulmonary vasoreactivity depended on postnatal age. The major effect of ventilating fetal lungs was on the middle region.

This article has been cited by other articles:

				J. L. Aschner, T. K. Smith, N. Kovacs, J. M. B. Pinheiro, and M. Fuloria Mechanisms of bradykinin-mediated dilation in newborn piglet pulmonary conducting and resistance vessels Am J Physiol Lung Cell Mol Physiol, August 1, 2002; 283(2): L373 - L382. [Abstract] [Full Text] [PDF]

				P.J. Boels, J. Deutsch, B. Gao, and S.G. Haworth Maturation of the response to bradykinin in resistance and conduit pulmonary arteries Cardiovasc Res, November 1, 1999; 44(2): 416 - 428. [Abstract] [Full Text] [PDF]