The selective in vivo incorporation and metabolism of radioactive putrescine in the adult male rat.

Putrescine (1,4, diaminobutane), a known precursor of the polyamines, spermine, and spermidine, was studied as a possible vehicle for a radioisotope scan of the prostate and other tissues rich in polyamines. Male Sprague-Dawley rats received intravenous injections (2.3 muCi/100 gm) of 3H putrescine dihydrochloride (specific activity, 107 muCi/muM). One hour after injection the ventral prostate and pancreas showed uptake of radioactivity that was three and four times greater than that of the liver, respectively. The ratio of the amount of radioactivity in the ventral prostate compared with that of abdominal wall musculature was 8:1. The pancreas-to-muscle ratio was 10:1. At 1 hr the ventral prostate contained 0.6% (0.9%/gm wet wt) of the total injected radioactivity and the pancreas, 0.5% (1.2%/gm wet wt) of the injected dose. More than 90% of the radioactivity in the rat ventral prostate, 6 hr after intravenous injection of 14C-putrescine dihydrochloride, was found to be in the form of spermine and spermidine, thus confirming previous in vitro biosynthetic studies.