Increased formation of diamines and polyamines in the pregnant rat.

1. The urinary excretion of histamine, methylhistamine, putrescine, cadaverine, spermidine and spermine was examined before, during and after pregnancy in rats. 2. During the last third of undisturbed pregnancy a distinct and steep rise occurred in the excretion of all amines studied except spermine. The peak values were found a few days before the birth of the young. In spermidine excretion a second peak was observed one or two days after delivery. 3. Before and during the first 2 weeks of gestation on a molar basis putrescine excretion was the greatest one. During the last trimester histamine was excreted in the largest amount. 4. Under the influence of the diamine oxidase inhibitor aminoguanidine the general pattern of excretion of diamines and polyamines in pregnant rats remained essentially unchanged but the total amount excreted increased. Most conspicuous was the great elevation of urinary contents of putrescine and cadaverine.