CO2 relaxation of the rat lung parenchymal strip.

Michael J Emery, Randy L Eveland, Jin-Hye Min, Jacob Hildebrandt, Erik R Swenson

Pulmonary and Critical Care Medicine (S-111-PULM), VA Puget Sound Health Care System, 1660 South Columbian Way, Seattle, WA 98108, USA. mjemery@u.washington.edu

Respiratory physiology & neurobiology 2013 Mar 1

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Evidence from liquid-filled rat lungs supported the presence of CO2-dependent, active relaxation of parenchyma under normoxia by unknown mechanisms (Emery et al., 2007). This response may improve matching of alveolar ventilation (V˙A) to perfusion (Q˙) by increasing compliance and V˙A in overperfused (high CO2) regions, and decrease V˙A in underperfused regions. Here, we have more directly studied CO2-dependent parenchymal relaxation and tested a hypothesized role for actin-myosin interaction in this effect. Lung parenchymal strips (∼1.5mm×1.5mm×15mm) from 16 rats were alternately exposed to normoxic hypocapnia ( [Formula: see text] ) or hypercapnia ( [Formula: see text] ). Seven specimens were used to construct length-tension curves, and nine were tested with and without the myosin blocker 2,3-butanedione monoxime (BDM). The results demonstrate substantial, reversible CO2-dependent changes in parenchyma strip recoil (up to 23%) and BDM eliminates this effect, supporting a potentially important role for parenchymal myosin in V˙A/Q˙ matching. Published by Elsevier B.V.

Citation

Michael J Emery, Randy L Eveland, Jin-Hye Min, Jacob Hildebrandt, Erik R Swenson. CO2 relaxation of the rat lung parenchymal strip. Respiratory physiology & neurobiology. 2013 Mar 1;186(1):33-9