Portal de Periódicos da CAPES

Development and preliminary application of a homologous radioimmunoassay for bullfrog growth hormone

1976; Elsevier BV; Volume: 30; Issue: 3 Linguagem: Inglês

10.1016/0016-6480(76)90087-3

1095-6840

Gisela K. Clemons,

Proteoglycans and glycosaminoglycans research

Abstract A homologous radioimmunoassay (RIA) for bullfrog growth hormone (fGH) with high sensitivity was developed. The fGH used for immunization was obtained by disc gel electrophoresis of frog anterior pituitaries. The fGH for iodination and standard was obtained from Dr. H. Papkoff. The RIA showed only minimal cross-reactivity with bullfrog prolactin, and plasma from hypophysectomized frogs had no detectable immunoreactive GH. The antiserum to the fGH inactivated 80% of the biological activity of fGH in the rat tibia test. The levels of immunoreactive fGH were determined in individual pituitaries and pooled plasma samples from Rana catesbeiana tadpoles through metamorphic climax (Taylor-Kolross stages XXI-XXV). Pituitary GH increased steadily from the emergence of the forelegs to the complete absorption of the tail when expressed as total GH per 10 g body weight. When expressed as percentage of pituitary protein content, the fGH concentration increased through stage XXIV and declined in stage XXV. Circulating levels of fGH increased significantly from stage XXI through stage XXIV and declined in stage XXV.