Expression and distribution of surfactant proteins (a,b,c) and
lysozyme in rat lung after prolonged hyperpnea..
Yogalingam, Gouri, Ian R. Doyle, John H. T. Power.
Department of Human Physiology, School of Medicine, Flinders
University of South Australia, Bedford Park 5042, Australia
APStracts 2:0160L, 1995.
We have induced prolonged hyperpnea in rats and examined the
distribution of surfactant associated proteins SP-A, SP-B, and
lysozyme in lamellar bodies (lb), and two alveolar fractions, one
tubular myelin rich (alv-1) and the other tubular myelin poor (alv
-2). We have also examined the expression of SP-A, SP-B, SP-C, and
lysozyme mRNA in both lung tissue and alveolar type II cells.
Hyperpnea resulted in significant increases in lb SP-A, lysozyme, and
phospholipid (PL) but no change in the protein/PL ratios suggesting
lb stoichiometry is constant. The SP-A and SP-B/PL ratio in control
alv-1 were 33 times and 18 times greater respectively than in lb
suggesting that alv-1 is enriched with these proteins. In contrast,
the lysozyme/PL ratio was similar to lb. Hyperpnea did not alter the
alv-1 SP-A or SP-B/PL ratios suggesting some constant stoichiometry
to their lipid association, however the lysozyme/PL ratio was
reduced. Whereas hyperpnea significantly elevated the PL, SP-A, and
lysozyme levels in alv-2, the SP-B level was unchanged. We suggest
that surfactant associated lysozyme is secreted with lb, the majority
of SP-A is linked to lipid secretion but not necessarily with lb, and
that the majority of SP-B secretion is independant of PL secretion.
Hyperpnea did not alter the mRNA expression of SP-A, SP-B, SP-C or
lysozyme in alveolar type II cells but SP-A and SP-B mRNA expression
were significantly increased in lung tissue.
Received 25 January 1995; accepted in final form 23 August 1995.
APS Manuscript Number L23-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.