Distribution of mast cells and the effect of their mediators on contractility in human myometrium.
OBJECTIVE
To examine the distribution of mast cells in human uterine tissue and to study the interactions between mast cell mediators (histamine and serotonin) and PGF2 alpha in human myometrium contractile activity.


METHODS
Distribution of mast cells were analysed in cryostat sections of myometrium samples stained with Toluidine blue. Contractile activity was evaluated in an isolated organ bath preparation on myometrial strips obtained from women whose pregnancies ended in elective caesarean section.


METHODS
Biological Science Laboratories at the University of Concepción.


METHODS
Twenty women undergoing elective caesarean and 10 women undergoing hysterectomy at the G. Grant Hospital.


METHODS
Cumulative concentration-response curves for histamine and serotonin before and after the addition of subumbral concentrations of the PGF2 alpha or serotonin were performed.


RESULTS
Serotonin was more active than histamine to evoke contractions (EC50:0.20 (SE 0.02) mumol/l vs 1.5 (SE 0.2) mumol/l, respectively). Furthermore, threshold concentrations of serotonin (0.05 mumol/l) potentiated the contractile effect of histamine (EC50:0.3 (SE 0.06) mumol/l and 50% increase in E(max)). PGF2 alpha had a poor contractile effect, but threshold concentrations (0.05 and 0.10 mumol/l) enhanced the contractile effect of both serotonin and histamine. A population of mast cells was found in close apposition to smooth muscle fibres.


CONCLUSIONS
It is postulated that the simultaneous release of mast cell mediators (histamine and serotonin) in myometrium could be an important stimulus for evoking strong contractions in the human uterus. PGF2 alpha may have indirect effects in myometrium by amplifying the effects of histamine and serotonin.
Rudolph
M I
MI
Departamento de Farmacologia, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile.
Reinicke
K
K
Cruz
M A
MA
Gallardo
V
V
Gonzalez
C
C
Bardisa
L
L
D015237:Dinoprost / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008407:Mast Cells / Q000166:cytology*; D009215:Myometrium / Q000166:cytology*; D012701:Serotonin / Q000494:pharmacology*; D014590:Uterine Contraction / Q000187:drug effects*
D012701:Serotonin; D006632:Histamine; D015237:Dinoprost