OXYTOCIN-MEDIATED COORDINATION OF RHYTHMOGENIC ACTIVITY IN THE MYOMETRIUM

The characteristics of spontaneous electrical activity forming bursts of action potentials in the main rhythmogenic areas of the myometrium (ovarian area, cervical area, uterine corpus) were investigated. The results were analyzed by determining the values of the following parameters of action potentials: amplitude (A), mean rise-rate (V), rise-time (T/2), and half-width (t). The obtained data indicate that the ovarian horn area represents a distinct rhythmogenic site, characterized by generation of bursts of discharges with properties unique to this area, in contrast to the activity patterns observed in the cervical horn area and uterine corpus. Oxytocin, through its excitatory action, induces a synchronous increase in the measured parameters across the studied areas to the same extent. Comparable alterations in the main activity characteristics were observed under conditions of complete isolation of each uterine horn locus. Administration of oxytocin following isolation of loci resulted in a marked increase in spike amplitude and rise rate of action potentials in the ovarian area, approaching values observed in norm. Thus, these findings indicate that the ovarian horn area serves as a leading rhythmogenic site. Morphochemical results demonstrated the presence of different "functional" states in the examined myometrial areas, which is consistent with the presented electrophysiological data.