Estudio de la actividad contractil uterina basal durante el ciclo estral de la rata

Introduction. The uterus has the capacity of spontaneous contraction; it has been demonstrated that segments of uterus in vitro present spontaneous contractions, even more active through that in conditions in live, which indicates that there exist factors that inhibit this type of contractions across a system of regulation that is suggested is for hormones; also, it is thought that it exists lateralizacion in the activity of the womb, being more active the right horn than the left. Objective. To determine if it exists lateralizacion functionally of the uterus and if the contractile spontaneous activity changes with the cycle estral in the rat. Material and method. There were used 36 rats Wistar, adult virgins; three estrales cycles registered by means of vaginal smear was determined each morning obtained 2 h after lights off. During different stages of the third cycle estral (matador, proestro early, proestro late, early estrus and late estrus) they were anesthetized and his uterine horns were exposed to realize during 10 min. the record of the contractile activity of the uterus in situ. Results. Did not find differences in the number of uterine contractions of the left horn vs. the right horn during the diverse stages of the estral cycle (F (5, 60) =0.06070; p=0.99745). The stage of the estral cycle had significant effect in the entire frequency of uterine contractions during 10 minutes of record. A major frequency was present during early proestro, late proestro, early estrus and late estrus compared to the early and late diestrus, where the minor frequency of contractions was observed (F: (5, 65) =9.7996, p=0.0000). Conclusions. These results show that it does not exist lateralization in the contractile activity of the uterus in the rat and that the hormonal state of the female plays an important role in the regulation of the uterine contractile activity; and due to this effect, the contractions appear of spontaneous form without the mechanical stimulation of the genital tract.