Lung function and the response to exercise in New Guineans: role of genetic and environmental factors

Abstract

1. Information on respiratory symptoms and, in most instances, the ventilatory capacity (forced expiratory volume and forced vital capacity) were obtained on 2026 men, women and children comprising the total population of 12 villages situated at 2000 m in the Eastern Highlands and 1736 coastal people on Karkar Island. On selected healthy adults measurements were made of the total lung capacity and its subdivisions, the transfer factor for the lungs for carbon monoxide (151 subjects aged 20-63 years) and the ventilation and the cardiac frequency during submaximal exercise (132 subjects aged 17-34 years). The transfer factor was standardized to a haemoglobin concentration of 14.6 g/100 ml and alveolar capillary oxygen tension of 14.7 kPa (110 Torr). 2. The ventilatory capacity was reduced by the presence of respiratory symptoms or a loose cough but not by smoking local tobacco (Brus). For subjects with apparently healthy lungs and after allowing for the effects of age and of stature, the ventilatory capacity of the highland men, women and children was similar to that of representative Europeans. The coastal people had lower values including lower partial regression coefficients on age. The total lung capacity, its subdivisions and the transfer factor for the adult highlanders were larger than for the coastal people; the values were similar to or larger than for Europeans. The values for the coastal people resembled those for people of Indian, African and Chinese descent living in the tropics. The partial regression coefficient of transfer factor on age in the New Guineans was more negative than in the Europeans. 3. For the healthy young adults, analysis of the lung function data in relation to those for exercise point to the differences between the groups being due to the combined effects of an ethnic factor plus differences in the level of physical activity. The lung volumes, ventilatory capacity and ventilation during exercise are the resultant of both effects. The exercise tidal volume is a function of the ethnic factor but not the level of activity, while the reverse is true of the lung transfer factor for carbon monoxide.