[Effect of isoptin and euphylline on calcium- and carbacholine-induced contractile activity of isolated intestinal strips of rats of various ages].

It has been shown on isolated strips of the large intestine of adult and 2-week-old rats that the potassium depolarized smooth muscle of the adult rat intestine reacts by contractions to less concentrations of Ca2+ as compared to 2-week-old rats. Euphylline blocked the reaction of the adult rat large intestine to Ca2+ more powerfully than isoptin. The effects of the spasmolytics on 2-week-old rats were less demonstrable in view of the unremarkable reaction to Ca2+ itself.

[Age-related aspects of the reaction of isolated strips of rat rectum and colon to carbacholine, atropine and pentamine].

Experiments in vitro were made to record isotonic contractions of isolated strips of the rectum and colon of rats distributed into 4 age groups. It was shown that in one-week-old rats, the rectal and colonic strips reacted to carbacholine (1 x 10(-10--1 x 10(-5) M) to a far less extent than those in adult rats. In the course of postnatal development the reaction of the colonic strips to carbacholine reached the adult rat level more rapidly.

[Effect of kynurenines on the actions of acetylcholine, oxotremorine, and nicotine].

Kynurenine, 3-hydroxyanthranilic, anthranilic and nicotinic acids at concentrations 10(-4) and 10(-5) M potentiated contractions of the isolated rat rectum produced by acetylcholine. Contractile response of the phrenico-diaphragmatic preparation of young rats to acetylcholine was diminished by kynurenine, 3-hydroxykynurenine and by quinolinic acid. In rats of both sexes, 3-hydroxyanthranilic, anthranilic, picolinic and nicotinic acids in doses of 10 and 20 mg/kg shortened the latency of oxotremorine tremor.

[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.