Uterotonic activity was determined in two synthetic prostaglandin derivatives designed for use in veterinary medicine: Remophan Spofa (99/104/89-C) and Glystrophan Spofa (the registration procedure is not yet finished). The uterotonic characteristics of these synthetic products are compared with those of the natural prostaglandins PG E2 and PG F2-alpha. The contractility of the smooth muscles of the uterus in vitro was measured in uterine slices of human and rat myometrium, using the modified Magnus-Kehrer apparatus. The new prostaglandin preparations showed a biphasic effect: their action depended on the concentration of the preparation in the reaction medium. The uterotonic activity of both synthetic products compares favourably with the uterotonic activity of PG F2-alpha. In the rat slice the Remophan Spofa derivative potentiates the action of PG F2-alpha and Glystrophan Spofa if it left to act in mixture.

Propranolol (1; Obsidan) relaxes in vitro stripes of smooth muscles of non-pregnant rat's uterus in a concentration dependent manner. In contrast, on uterine muscle stripes of pregnant rats 1 causes small contractions. In an combination of 1 and fenoterol (2; Partusisten) (20:1) 1 prevents the relaxing effect of 2, reported to be an inhibitor of uterine muscle activity. This antagonism is most distinct on stripes of pregnant rat's uterus.

The effects of terguride on the uterotonic activity of rat's uterine stria were investigated by means of a standardized isometric method of measuring in vitro the contractility of uterine muscles. The uterotonic activity of the given preparation depends on its concentration and on the phase of uterine cycle. The uterotonic activity makes 71.4 U.mg-1 in the range of terguride concentrations from 10(-7) to 10(-5) mg per ml. Used at higher concentrations, the uterotonic activity of terguride is very low. Spontaneous contractions are moderated and the tone of uterus is decreased by terguride administration.

The isometric method of assessment of the contractility of uterine strips in vitro makes it possible to follow up systematically the response of smooth uterine musculature to oxytocin and to test the effect of selected preparations on this process. In the submitted work the author investigated the effect of methyloxytocin, magnesium sulphate, seduxene, phenergan, plegomazine and DH-ergotoxin on the uterine contractions of strips of rat and human uteri ted. Based on the results of model experiments in vitro, the author discusses the effect of the mentioned substances on the spasmogenic activity of oxytocin.

Inhibitory effects of Partusisten, Dilatol, Papaverin and Magnesium-sulfat on the activity of smooth muscle were tested in vitro on 18 isolated stripes of rats uteri, exhibiting both a high sensitivity against oxytocin and a distinct spontaneous activity. Minimal inhibitory concentrations of all drugs tested were determined, and their influence on the frequency and amplitude of contraction as well as on lag phase between inhibition and onset of spontaneous activity were registered. Basing on these experimental data conclusions were drawn concerning their clinical relevance.

Using a standard isometric method, the authors investigated the effect of some cations and nifedipine on the contractility of isolated strips of the human uterus in vitro. Evidence was provided that the contractility depends on the extracellular surface concentration of the calcium cation. Under the experimental set-up used intracellular calcium does not play any part and the contractions of the uterine strip depend on the state of the calcium channels.