The affinity spectrum method has been used to analyse binding isotherms for [3H]-oxytocin to rat myometrial plasma membranes. Three populations of binding sites with dissociation constants (Kd) of 0.6-1.5 x 10(-9), 0.4-1.0 x 10(-7) and 7 x 10(-6) mol/l were identified and their existence verified by cluster analysis based on similarities between Kd, binding capacity and Hill coefficient. When experimental values were compared to theoretical curves constructed using the estimated binding parameters, good fits were obtained. Binding parameters obtained by this method were not influenced by the presence of GTP gamma S (guanosine-5'-O-(3-thiotriphosphate) in the incubation medium. The binding parameters agree reasonably well with those found in uterine cells, they support the existence of a medium affinity site and may allow for an explanation of some of the discrepancies between binding and response in this system.

The objectives of this study were to determine the effects of pregnancy in the rat on the contractile response of the myometrium in vitro to a number of prostanoids. Longitudinally and circularly oriented strips were studied separately. Responses to PG (prostaglandin)F2 alpha, PDG2, the PGI2-mimetic iloprost, and the thromboxane (Tx) A2-mimetic U-46619 were investigated on Days 10, 15, 18, 20, 21, and 22 of pregnancy. Responses were prostanoid-dependent, and differences between longitudinal and circular strips were small. PGF2 alpha and PGD2 produced similar patterns, with a high potency but low maximal response on Day 10; thereafter potency fell to a minimum value on Day 18 and then gradually increased until Day 22, when it was still lower than at Day 10. In contrast, for PGE2 there were no changes in potency over the period of study (longitudinal muscle) or a slight increase between Days 15 and 21 (circular muscle). Both iloprost and U-46619 maintained a low potency throughout pregnancy. We conclude that the pregnant rat's myometrium is probably not a target for PGI2 or TxA2 and that the difference patterns of responses to PGE2 and PGF2 alpha during pregnancy support the hypotheses that these prostanoids act at different sites within the myometrium.

SummaryThe regional occurrence of cystic echinococcosis in slaughtered pig from Slovakia was studied in the period of 2000 -2008, along with the quantitative parameters associated with the establishment of cysts (intensity of infection, fertility, size). From 103 pig livers collected from abattoirs in 35 sites Slovakia as suspected for Echinococcus infection, 63 were positive for cystic echinococcosis, whereas in 40 livers cysticercosis was diagnosed. Fertile cysts with echinococcal protoscoleces were recorded in 25.4 % of positive pigs, with the 8.9 % fertility rate and the intensity of infection reaching value of 5.9 cysts per liver. The average size of fertile cysts was more than three times larger than diameter of sterile cysts (diameters of 4.67 cm vs. 1.37 cm, respectively). No significant differences in relative amounts of fertile and sterile cysts were found among counties (P = 0.15). The annual prevalence of E. granulosus in pigs in 2000 -2 008 has ranged from 0.02 % to 0.13 % (average rate 0.08 %), with the decreasing tendency over the period, especially after 2005. The most heavily affected areas with cystic echinococcosis over -2008 and Komárno districts (southwestern Slovakia, 0.26 % prevalence). Obtained data are relevant in designing regional control strategies to suppress the occurrence of disease in livestock and risk for humans to be infected.

Prostanoid receptors regulating the contractility of strips of myometrium obtained from nonpregnant ewes during the breeding season were classified pharmacologically. Natural prostanoids, receptor-type selective synthetic analogues, and selective antagonists were used where available. The natural prostanoids PGD2, PGE2, and PGF2 alpha were equipotent in causing contractions (pD2 values of 6.9, 6.7, and 6.9, respectively) but were 100 times less potent than oxytocin (pD2 = 9.2). The synthetic prostanoids iloprost (pD2 = 8.3), GR63799x (pD2 = 7.0), cloprostenol (pD2 = 6.8), and U46619 (pD2 = 6.2) also caused contractions. The effects of iloprost, but not of GR63799x, were blocked by the selective EP1 antagonist AH 6809. This suggests the presence of both EP1 and EP3 receptors. The similar potencies of cloprostenol and PGF2 alpha suggest the presence of FP receptors. Although the potency of the TP agonist U46619 was relatively low, its effects were blocked by the selective TP antagonist L 670596 (pKB = 8.4), an observation consistent with the presence of TP receptors. Thus, all currently recognized excitatory prostanoid receptors (EP1, EP3, FP and TP) appeared to be present. Contractions induced by cloprostenol and KCl could be inhibited by the beta-adrenoceptor agonist isoprenaline (pD2 = 8.8 against cloprostenol) and the Ca(2+)-channel blocker, D600 (pD2 = 6.3 against cloprostenol), but a number of relaxant prostanoids, BW245c, ZK110841, AH13205 and cicaprost, could not produce inhibition. These results suggest that DP, EP2 and IP receptors do not regulate contractility under these conditions.

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