Studies on the stability of rat testis membrane receptors for hLH, hCG and hFSH

Receptor preparations from rat testes were stored at 4 C with various protease inhibitors and chemicals, at -20 C and -80 C, in freeze-dried form as well as at 4 C and 37 C after reconstitution in various media. Each preparation was tested for stability in terms of binding capacity of human luteinizing hormone (hLH), human chorionic gonadotropin (hCG) and human follicle-stimulating hormone (hFSH). The freeze-dried samples were stable for at least six months, although once reconstituted and stored at 4 C, they were less stable than fresh ones. Furthermore, Na azide and Na azide with diisopropylfluoro-phosphate (DIFP) prolonged the stability of the fresh samples. The samples stored at -20 C or -80 C were stable for at least 90 days and repeated freezing and thawing (15 times) did not change the binding capacity of either the hCG/hLH or hFSH receptors.