Limit Of Compensatory Lung Growth Was Reached Following 70% Resection In Adult Canine Lung

In adult foxhounds, compensatory alveolar tissue growth was stimulated in all lobes following 58% resection but not in most lobes following 42% resection ( J Clin Invest 92:1993 and 94: 1994 , Respir Physiol Neurobiol 151:2006). To examine whether the intensity of growth increases with the intensity of resection, we performed two‐stage surgery in 11 animals to remove ~70% of lung units using a balanced (B, equal fraction remaining on each side, n=9) or an unbalanced (U, left middle and lower lobes remaining, n=2) approach. Lungs were fixed 3 yr later. Extravascular alveolar tissue volume (V tiss ) was expressed as a ratio with respect to the corresponding lobe of unoperated animals (n=6), and compared to that following 42% (n=12) and 58% (n=10) resection. V tiss (resection/control)Lobe 42% 58% ~70%L cranial2.10±1.27 * 1.28±0.43L middle2.82±1.28 * 1.62±0.59 *L caudal2.68±0.81 * 1.58±0.23 *R cranial 1.04±0.30 1.51±0.40 * †R middle 0.99±0.39R caudal 0.94±0.30R cardiac 1.71±0.58 *All remaining lobes 1.08±0.27 2.38±0.64 * † 1.43±0.32 ‡ (B) 1.93±0.60 * † (U)Mean±SD. p≤0.05 by ANOVA: * vs control (1.0), † vs 42% and ‡ vs 58% resection.Data show heterogeneous increases in V tiss following 70% resection; the magnitude of increase was significantly less than that following 58% resection. Data suggest that there is a range of resection where in vivo signals elicit optimal compensatory lung growth. Support: NHLBI R01‐HL40070, 62873