Endocrine influences on aspects of lung biochemistry

Evidence is presented that the postnatal rat lung is receptive to several hormones. Experimental diabetes caused a significant depression in lung glucose oxidation rate which was normalized by exogenous insulin therapy. Diabetes also depressed the rate of amino acid incorporation into lung protein; in vitro, insulin stimulated synthesis of selective protein species by the diabetic lung. These results, together with the demonstration of pulmonary receptor sites for insulin and the observation that diabetes selectively affects the ultrastructure of only two cell types in the lung, suggest that insulin may be an important regulator of lung function. That androgens and oestrogens may also exert an effect on the lung is suggested by the presence of distinct receptor activities for these hormones, which appear to be influenced by serum titres of the gonadal steroids. The lung is capable of generating a considerable amount of cyclic GMP in vitro. This ability appears to be dependent upon continued protein synthesis and is influenced by the endocrine state of the animal. Certain steroid hormones are capable of altering cyclic GMP production by the lung when introduced in vitro.