Inhibitor sensitivity of pulmonary vascular carbonic anhydrase

T. A. Heming*, C. G. Vanoye, E. K. Stabenau, E. D. Roush, C. A. Fierke, A. Bidani

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


The inhibitor sensitivity of pulmonary vascular carbonic anhydrase (CA) was examined in situ to identify the specific isozyme responsible for vascular activity and to study its distribution in the lung. Vascular CA activity was monitored in isolated rat lungs by measuring the rate of CO2 excretion and the magnitude of postcapillary CO2-HCO3-H+ disequilibria. Lungs were perfused with isotonic salines containing gluconate, sulfate, Cl, or I-, with or without sulfonamide derivatives. Effects of a CA inhibitor purified from porcine blood plasma were also determined. Vascular CA activity was unaffected by gluconate, sulfate, Cl, and I- (≤100 mM). Sulfonamides with vastly different rates of membrane permeation (i.e., readily permeating ethoxzolamide, slowly permeating acetazolamide, and membrane-impermeant quaternary ammonium sulfanilamide) were capable of accessing all vascular CA with similar rates of access. The porcine inhibitor of CA (340 nM) produced a significant, but submaximal, inhibition of vascular CA activity. The data suggest that pulmonary vascular activity reflects a high-activity membrane- bound isozyme, CA IV, which is located on the extracellular luminal surface of capillary endothelial cells.

Original languageEnglish (US)
Pages (from-to)1642-1649
Number of pages8
JournalJournal of applied physiology
Issue number4
StatePublished - 1993


  • capillary gas exchange
  • carbon dioxide
  • lungs
  • rat

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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