Proteolysis in the rat lung: hypoxia and evidence for an inhibitor of proteolysis.

M. J. Chiang, F. Kishi, P. Whitney, D. Massaro

Research output: Contribution to journalArticle

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Abstract

We labeled proteins with [14C]phenylalanine in rats breathing air and assessed the rate of proteolysis in the isolated ventilated lung by measuring the accumulation of [14C]phenylalanine in the medium perfusing the lung. Ventilation with 0% O2 decreased the rate of proteolysis and the ATP content in the lung 60%. Medium from lungs ventilated with 0% O2, when used to perfuse lungs ventilated with 95% O2, decreased the rate of proteolysis 60% without lowering the ATP content of the lung. Correcting the pH of "used" medium or dialyzing used medium did not decrease its ability to inhibit proteolysis. Used medium from nonhypoxic lungs, or exogenous lactate (50 mM), diminished proteolysis only 20%. In a cell-free system the degradation by cathepsin D of radioactive lung proteins and radioactive hemoglobin was decreased by used medium from hypoxic lungs. We conclude that the hypoxic perfused lung releases a factor(s) that decreases the rate of proteolysis in nonhypoxic lungs and that this factor may be a protease inhibitor.

Original languageEnglish
JournalThe American journal of physiology
Volume241
Issue number2
StatePublished - Aug 1 1981

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Proteolysis
Lung
Phenylalanine
Hypoxia
Adenosine Triphosphate
Cathepsin D
Cell-Free System
Protease Inhibitors
Ventilation
Lactic Acid
Respiration
Hemoglobins
Proteins
Air

ASJC Scopus subject areas

  • Medicine(all)

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Proteolysis in the rat lung : hypoxia and evidence for an inhibitor of proteolysis. / Chiang, M. J.; Kishi, F.; Whitney, P.; Massaro, D.

In: The American journal of physiology, Vol. 241, No. 2, 01.08.1981.

Research output: Contribution to journalArticle

Chiang, M. J. ; Kishi, F. ; Whitney, P. ; Massaro, D. / Proteolysis in the rat lung : hypoxia and evidence for an inhibitor of proteolysis. In: The American journal of physiology. 1981 ; Vol. 241, No. 2.
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