Key points are not available for this paper at this time.
Follicle-stimulating hormone was labeled with tritiated borohydride after initially oxidizing the hormone with periodate. The radioactive label was introduced into the altered sialic acid fragment, NAN-7, which remained susceptible to Clostridium perfringens neuraminidase. Fifty per cent of biologic and immunologic activities of native FSH was preserved. When 3H-FSH was injected into the tail vein of pseudopregnant or intact immature female Sprague Dawley rats, maximum ovarian concentration of 3H occurred within 5 min in the pseudopregnant and 1 hr in the immature rat but did not exceed plasma 3H concentration until 3–4 hr after injection. The tritiated FSH preparation remained biologically active for more than 4 months after labeling. The long half-life of tritium is an added advantage. (Endocrinology89: 1356, 1971)
VAITUKAITIS et al. (1971) studied this question.