Journal of Applied Physiology, Vol 62, Issue 5 2031-2041, Copyright © 1987 by American Physiological Society

ARTICLES

Correlation of pulmonary ACE activity and capillary surface area during postnatal development

B. R. Pitt, G. Lister, P. Davies and L. Reid

Although a considerable amount of information is available regarding the remodeling and growth of the pulmonary arterial circulation, relatively little is known regarding postnatal development of the pulmonary microcirculation. We hypothesized that the maximal velocity (Vmax) of pulmonary angiotensin-converting enzyme (ACE) activity, measured from indicator-dilution outflow curves using a synthetic substrate, 3H-labeled benzoyl-phenylalanyl-alanyl-proline (BPAP), is directly related to the capillary endothelial cell surface area in the lungs of developing lambs. Accordingly we measured apparent kinetics of pulmonary ACE activity in 22 anesthetized ventilated lambs (2-171 days old) and compared our functional assessment to simultaneous in vivo determinations of CO diffusing capacity (DLCO) and postmortem structural assessment of alveolar septal dimensions using stereology and electron microscopy. There was a progressive increase in Vmax of ACE in this age group, with little change in apparent affinity for BPAP. Similar functional manifestation of growth was noted by an age-dependent increase in DLCO. Neither Vmax nor DLCO was significantly affected by an increase in left atrial pressure to 19 Torr (via inflation of a balloon in the left atrium), suggesting little recruitment of vessels under conditions of the present protocol. A close correlation was observed when either Vmax for ACE activity or DLCO was plotted vs. capillary endothelial cell surface area. Double logarithmic transformation of capillary endothelial cell surface area, Vmax-ACE and DLCO vs. lung volume revealed power functions with slopes all greater than that predicted from isotropic growth, suggesting selective differential postnatal development of the endothelium of the alveolar septum in lambs from 2-171 days of age.

This article has been cited by other articles:

				S. Sarlos and J. L. Wilkinson-Berka The Renin-Angiotensin System and the Developing Retinal Vasculature Invest. Ophthalmol. Vis. Sci., March 1, 2005; 46(3): 1069 - 1077. [Abstract] [Full Text] [PDF]

				J S Forsyth, J Reilly, C G Fraser, and A D Struthers Angiotensin converting enzyme activity in infancy is related to birth weight Arch. Dis. Child. Fetal Neonatal Ed., September 1, 2004; 89(5): F442 - F444. [Abstract] [Full Text] [PDF]

				C. Staniloae, A. J. Schwab, A. Simard, R. Gallo, I. Dyrda, G. Gosselin, J. Lesperance, J. W. Ryan, and J. Dupuis In vivo measurement of coronary circulation angiotensin-converting enzyme activity in humans Am J Physiol Heart Circ Physiol, January 1, 2003; 284(1): H17 - H22. [Abstract] [Full Text] [PDF]

				L. E. Fisher Jr., A. Cziraki, C. M. Steinhart, and J. D. Catravas Unaltered pulmonary capillary surface area in the presence of changing arterial resistance Am J Physiol Lung Cell Mol Physiol, February 1, 1998; 274(2): L264 - L269. [Abstract] [Full Text] [PDF]

				S. Prié, T. K. Leung, P. Cernacek, J. W. Ryan, and J. Dupuis The Orally Active ETA Receptor Antagonist (+)-(S)-2-(4,6-dimethoxy-pyrimidin-2-yloxy)-3-methoxy-3,3-diphenyl-propionic acid (LU 135252) Prevents the Development of Pulmonary Hypertension and Endothelial Metabolic Dysfunction in Monocrotaline-Treated Rats J. Pharmacol. Exp. Ther., September 1, 1997; 282(3): 1312 - 1318. [Abstract] [Full Text]

				S. H. MITCHELL and W. GERALD TEAGUE Reduced Gas Transfer at Rest and during Exercise in School-age Survivors of Bronchopulmonary Dysplasia Am. J. Respir. Crit. Care Med., May 1, 1997; 157(5): 1406 - 1412. [Abstract] [Full Text]