This present study was performed to inverstigate the response of the uterine receptors to chemical substance, i.e potassium chloride, bradykinin and capsaicin which are known as algesic substance and to examine the chemoreceptive properties of
uterine
receptors for them.
The recordings were done from 29 single uterine afferents in the hypogastric nerve of alpha-chloralose anesthetized cat.
@ES The results are as follows,
@EN 1. The twenty nine uterine afferents that obtained in this study were composed of 9 A-delta fibers and 20 C fibers.
2. The response to von Frey hair were showed in 27 uterine afferents. The higher the stimuli was applied, the larger the magnitude of response was revealed, and so they showed graded response.
3. Bradykinin (2~10 μunits(74.1%) showed response of increased impulse discharage to the injected bradykinin and it was followed by intense uterine contraction. And the response had dose dependent relationship to the injected bradykinin. But
the
initiation of uterine contraction preceded the response of uterine afferents to bradykinin in time relation.
4. 10 of 20 uterine afferents(50%) were stimulated when capsaicin(1~2μg) was injected as a bolus into the uterine artery. The response of uterine afferents and uterine contraction had similar pattern with the bradykinin in dose dependent
relation
and
chronological sequence. In the nerve activity, there is no significant desensitizing effect but the uterine contraction curve had tendency to diminish with the serial injection of capsaicin.
5. 13 of 15 units(86.7%) revealed increased response when tested with potassium chloride of dose from 0.1 ml of 0.15M to 0.1 ml of 0.3M concentration. Comparing with the response to bradykinin and capsaicin, the duration of response was smaller
but the
peak discharge was larger. The two units did not show any response to bradykinin and capsaicin but excited only by potassium chloride.
6. Loperamide, smooth muscle relaxant, diminished the magnitude to uterine contraction at lower dose(2~10μg) and completely abolished the contraction at higher dose (20μg). But the response of uterine afferents to bradykinin persisted yet
inspite of
complete abolition of contraction.
Io summarize the above results, uterine receptors were activated by the various algesic chemicals injected through uterine artery and they showed persistent response during elimination of uterine contraction. It could suggest that there might be
uterine
receptors that have chmoreceptive properties.
|