[Age and the effect of proserine on the contractile response of the rectum and inhibition of its cholinesterase in rats].

The motor reaction of the rectum strips in rats of 4 age groups and inhibition of its cholinesterase with proserine were studied. To low proserine concentrations (1.10(-8)-1.10(-6) M) the intestine of 1-week old rattlings was found to react only by relaxation, contractions appearing only with a concentration of 1.10(-5) M. The maximal contractile reaction of the intestine to proserine was found to occur in 4-week old rattlings. The cholinesterase activity in the rectum of 1-week old rattlings is lower, and in the 4-week old ones higher than in adult animals. The inhibition of cholinesterase occurs in all the age groups from a minimal tested proserine concentration (1.10(10) M), gaining in strength parallel with increasing concentration. The maximum inhibition of the enzyme was found to occur in the 4-week old rattlings.