STAPHYLOCOCCUS AUREUS PAPTIDOGLYCAN’S EFFECT ON THE MYOMETRIAL SPONTANEOUS CONTRACTILITY OF PREGNANT RATS
DOI:
https://doi.org/10.11603/1811-2471.2020.v.i3.11594Keywords:
myometrium, peptidoglycan, Staphylococcus aureus, intracellular calcium level, myometrial contractionsAbstract
Peptidoglycan of Staphylococcus aureus is a structural element of the bacterial cell wall. It is released during the lifespan of bacterial cells and propagated by the bloodstream to the cells with tropism to it. In such tissues it is able to initiate some pathological processes. Staphylococcus aureus is often sown from the female genitourinary tract. It is known that the interaction of peptidoglycan with endothelial and decidual cells of the uterus during pregnancy initiates such complications as preeclampsia, stimulation of uterine contractility, and preterm birth. However, the mechanisms of action of peptidoglycan on the myometrium have not yet been precisely studied.
The aim – to determine whether peptidoglycan affects the myometrial spontaneous contractility in pregnant rats when the endometrium is removed, to study the character of spontaneous myometrial contractions in pregnant rats under peptidoglycan and the mechanisms of the revealed effects.
Material and Methods. The experiments were conducted on myometrial smooth muscle strips of pregnant Wistar rats. The myometrial contractility was studied by tensometry method.
Results. Experimental results showed that peptidoglycan modulates all the main parameters of spontaneous uterine contractions in the absence of endometrium. It increased the amplitude and duration of contractions by an average of 18.5 % and 16 %, respectively. At the same time, the frequency of spontaneous contractions decreased by an average of 10.5 %. A number of parameters indicated an increase in the intensity of myometrial contractions under peptidoglycan. In addition, the ratio of the contraction phases changed: under the action of peptidoglycan, myometrial spontaneous contractions had a relatively short but high-amplitude contraction phase, a rather long tonic component, and slow relaxation. The indicated phases of myometrial contractions under peptidoglycan increased by an average of 11.26 %, 69.23 % and 44.34 %, respectively. Under the blockers of L-type potential-gated calcium channels and IP3-receptors, peptidoglycan did not stimulate myometrial contractions.
Conclusions. The peptidoglycan has a stimulating effect on myometrial spontaneous contractility by acting directly on the myometrium. The modulating effect of peptidoglycan on myometrial contractility in pregnant rats is associated with an increase in the intracellular calcium level in smooth uterine myocytes, which is achieved due to an increase in the transmembrane calcium entry and its release from the sarcoplasmic reticulum.
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