Expression and distribution of surfactant proteins and lysozyme after prolonged hyperpnea.
We have induced prolonged hyperpnea in rats and examined the distribution of surfactant-associated proteins (SP-A and 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 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-to-PH ratios, suggesting that lb stoichiometry is constant. The SP-A and SP-B-to-PL ratios were 33 and 18 times greater, respectively, in control alv-1 than in lb, suggesting that alv-1 is enriched with these proteins. In contrast, the lysozyme-to-PL ratio was similar in control alv-1 and lb. Hyperpnea did not alter the alv-1 SP-A or SP-B-to-PL ratios, suggesting some constant stoichiometry to their lipid association; however, the lysozyme-to-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 the majority of SP-B secretion is independent 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 expression of SP-A and SP-B mRNA was significantly increased in lung tissue.
Yogalingam
G
G
Department of Human Physiology, School of Medicine, Flinders Univeristy of South Australia, Australia.
Doyle
I R
IR
Power
J H
JH
D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D015342:DNA Probes; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008168:Lung / Q000378:metabolism*; D008297:Male; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009113:Muramidase / Q000096:biosynthesis*; D015388:Organelles / Q000378:metabolism / Q000648:ultrastructure; D011510:Proteolipids / Q000032:analysis / Q000096:biosynthesis*; D011650:Pulmonary Alveoli / Q000378:metabolism; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000032:analysis / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains; D012119:Respiration
D017931:DNA Primers; D015342:DNA Probes; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D009113:Muramidase