Adaptive response to pneumonectomy in puppies.

Abstract

When left pneumonectomy was performed on 9-week-old puppies, the right lung increased in weight, volume, surface area, and number of alveoli so that at age 20 weeks these variables were the same as those of both lungs of control animals and significantly larger than those of the right lung of control animals. The adaptive response of the right lung after pneumonectomy was greater in the lower lobe than in the middle or cardiac lobes. The number of alveoli per ml and the average interalveolar wall distance, hence the surface to volume ratio, was the same in both lungs of control animals and the same in the cardiac, middle, and lower lobes of their right lungs.After pneumonectomy in experimental animals, the contralateral lung increases in volume, weight, collagen content, protein and deoxyribonucleic acid (DNA) to approximate to the values in both lungs of control animals.1-12 There are conflicting views on the effect of pneumonectomy on alveolar multiplication,3 4 6 8 10 11 13-19 and these have been reviewed elsewhere.19 In part, the reason for the controversy stems from older and less rigorous methods of counting alveoli, but also results from inherent practical and theoretical difficulties in counting alveoli and calculating alveoli per unit volume.'9 20In general, alveolar surface area increases directly with lung volume after pneumonectomy rather than to the 2/3 power which would be expected by simple overinflation, suggesting increased complexity of alveolar surface. This could be brought about either by lengthening of alveolar septa'8 19 or increased alveolar number.'9 We found that, after pneumonectomy in 10-week-old rabbits, the contralateral lung increased in volume, surface area, and alveolar number to the levels of these variables in both lungs of controls four weeks later.10 In rats, the adaptive response was less complete; when pneumonectomy was performed at 12 weeks of age, the relative response to the contralateral lung was less than when pneumonectomy was performed at 4 to 8 weeks of age.'9 Statistically significant alveolar multiplication did not occur when pneumonectomy was performed at 12 weeks of age.The only previous study in dogs showed that the average alveolar diameter was increased in the contralateral lung of two adult dogs after pneumonec- tomy but not when pneumonectomy was performed on three puppies.'4 These data suggest that alveolar multiplication occurs after pneumonectomy in puppies but not in adult dogs. Dogs are highly suitable animals for the study of lung mechanics and gas exchange and we wondered what the adaptive response would be to pneumonectomy performed in puppies. In this paper we describe the morphological findings. MethodsLeft pneumonectomy was performed on four male and four female mongrel puppies, 9 weeks old. Three male and four female mongrel puppies of the same age, litter mates of the experimental animals, underwent similar anaesthesia and a chest wall incision without entering the pleural cavity. It has been shown that collapse of the lung will induce...

Compensatory lung growth occurs in adult dogs after right pneumonectomy.

“…DLO2 was estimated by a modified version (13) of the previously established morphometric model (11,14). The model describes the gas diffusion path from alveolar air to the binding sites on hemoglobin as two serially linked conductance steps through the tissue and plasma barrier (Dbo2) and the erythrocyte (Deo2): DLoj ' = Dboj ' + Deoj' (1) where Dbo = Kbo0 (Sa + S.) (2) (21=hb) Sa and S, are the measured total alveolar and capillary surface area, and V. the measured total capillary blood volume. Thb is the harmonic mean thickness of the combined tissue and plasma barrier.…”

“…It is generally believed that postpneumonectomy compensatory lung growth occurs in immature dogs but not in fully mature dogs (1)(2)(3). In adult dogs, postpneumonectomy compensation is largely attributed to use of existing functional reserves in the remaining lung.…”

Prenatal Dexamethasone Treatment Improves Survival of Newborn Rats during Prolonged High O2 Exposure

“…To calculate the mean linear intercept (L M ) (representing the average distance between air space walls, or average airspace diameter), we used the formula LM = n -Lj'ei, where n is the number of lines counted, L is the length of the line, and ei is the sum of septal (walls of air spaces) intercepts. To calculate the ISA, we use the formul a ISA = 4· VL/LM , where VL is the postfixation lung volume by water displacement (21,22).…”

Characterisation of post-pneumonectomy lung growth in adult mice

“…Furthermore, the cellular components which contribute to repair and remodelling of pulmonary tissue still await ultimate elucidation. Solutions to the problems concerning repair and regeneration of lung tissue for restoration of functional alveoli are at the cutting edge of identifying novel therapeutic options for lung diseases like chronic obstructive pulmonary disease (COPD) and fibrosis.It has been previously reported that partial resection of the lung results in a rapid compensatory growth process of the remaining lung tissue, restoring normal lung volume, cell mass and organ function, in a variety of mammalian species [2][3][4][5][6]. Compensatory lung growth following unilateral pneumonectomy (PNX) has been documented for dogs, rabbits, ferrets, rats and mice.…”

“…It has been previously reported that partial resection of the lung results in a rapid compensatory growth process of the remaining lung tissue, restoring normal lung volume, cell mass and organ function, in a variety of mammalian species [2][3][4][5][6]. Compensatory lung growth following unilateral pneumonectomy (PNX) has been documented for dogs, rabbits, ferrets, rats and mice.…”