Leupeptin inhibits ventilator-induced diaphragm dysfunction in rats

Am J Respir Crit Care Med. 2007 Jun 1;175(11):1134-8. doi: 10.1164/rccm.200609-1342OC. Epub 2007 Mar 22.


Rationale: Controlled mechanical ventilation (CMV) has been shown to result in elevated diaphragmatic proteolysis and atrophy together with diaphragmatic contractile dysfunction.

Objectives: To test whether administration of leupeptin, an inhibitor of lysosomal proteases and calpain, concomitantly with 24 hours of CMV, would protect the diaphragm from the deleterious effects of mechanical ventilation.

Methods: Rats were assigned to either a control group or 24 hours of CMV; animals in the ventilation group received either a single intramuscular injection of saline or 15 mg/kg of the protease inhibitor, leupeptin.

Measurements and main results: Compared with control animals, mechanical ventilation resulted in a significant reduction of the in vitro diaphragm-specific force production at all stimulation frequencies. Leupeptin completely prevented this reduction in force generation. Atrophy of type IIx/b fibers was present after CMV, but not after treatment with leupeptin. Cathepsin B and calpain activities were significantly higher after CMV compared with the other groups; this was abolished by treatment with leupeptin. Significant inverse correlations were found between diaphragmatic force generation and cathepsin B and calpain activity, and illustrate the deleterious role of proteolysis in diminishing diaphragmatic force production after prolonged CMV.

Conclusions: Administration of the protease inhibitor leupeptin concomitantly with mechanical ventilation completely prevented ventilation-induced diaphragmatic contractile dysfunction and atrophy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Calpain / antagonists & inhibitors
  • Calpain / metabolism
  • Cathepsin B / antagonists & inhibitors
  • Cathepsin B / metabolism
  • Diaphragm / drug effects*
  • Diaphragm / enzymology
  • Diaphragm / physiopathology
  • Disease Models, Animal
  • Fluorometry
  • Male
  • Mercaptopurine / therapeutic use*
  • Muscle Contraction / drug effects
  • Muscle Contraction / physiology
  • Muscular Diseases / drug therapy*
  • Muscular Diseases / etiology
  • Muscular Diseases / physiopathology
  • Nucleic Acid Synthesis Inhibitors / therapeutic use*
  • Rats
  • Rats, Wistar
  • Respiration, Artificial / adverse effects*
  • Treatment Outcome


  • Nucleic Acid Synthesis Inhibitors
  • Mercaptopurine
  • Calpain
  • Cathepsin B