ABSTRACT
48 women with normal (38-40 weeks) and premature (38-37 weeks) labor were examined. The rate of deamination of serotonin, tyramine, beta-phenylethylamine, putrescine, cadaverine and histamine in samples containing extracts of the control group placenta averaged 0.86; 0.62; 0.18; 0.145; 0.63; 0.12 (nmoles NH3 per I mg of protein within I min), respectively. In the placental extracts obtained after the premature labor the rate of deamination of the substrates studied was decreased and constituted 0.4; 0.23; 0.108; 0.105; 0.29 and 0.084 nmoles NH3, respectively. The decrease in the rate of deamination of the amines studied, exhibiting high biological activity, appears to be responsible for premature labor. In the control group a correlation was found between the rates of serotonin and tyramine deamination as well as of putrescine and cadaverine deamination. The rates of deamination of mono- and diamines did not correlate. Deamination of beta-phenylethylamine and histamine did not depend also on deamination of other substrates studied. The data obtained demonstrate the presence in placenta of at least two forms of the enzymes, deaminating monoamines (one form for serotonin and tyramine and the other form for beta-phenylethylamine) as well as two forms of diamine oxidase - one form deaminating cadaverine and putrescine and the second form - histamine.
