An analysis of the effect of age on respiratory and digestive functions of the rat

Abstract

There is little published information on the pulmonary function of aged rats. The data available indicate that the elastic properties of the lung-thorax system of the rat changes with age in a fashion similar to that seen in the case of man and other mammals. However, unlike the situation observed with man, neither the internal surface area of the lungs nor the diffusing capacity of the lungs declines as the rat ages. The diffusion of O₂ from blood to tissues does not seem to decline with age in the rat and the utilization of O₂ by the tissues is either not affected by old age or affected in a subtle fashion. There is no information on how old age influences either the motility or the secretory activity of the exocrine glands of the alimentary tract of rats. There is abundant evidence to indicate that the processes involved in the absorption of dietary carbohydrate and protein are not adversely affected by old age in rats. The data on the effect of age on the enzymatic digestive process are not totally clear, but it seems unlikely that if such changes do occur that they are of a magnitude to seriously hamper the digestive function of the senescent rat.