Acidic pH and increasing [Ca(2+)] reduce the swelling of mucins in primary cultures of human cervical cells.
BACKGROUND
Cervical mucus is a heterogeneous mixture of water, ions and mucins that form a hydrophilic polymer gel. Mucins, the main components of mucus, are condensed inside secretory granules and swell to become a hydrogel after exocytosis. Using human cervical secretory cell primary cultures, the effect of [Ca(2+)] and [H(+)] on the swelling velocity of mucin granules was investigated in vitro.


RESULTS
Immunocytochemistry demonstrated that estrogen and progesterone receptors were expressed in cultured secretory cells along with mucins type 1, 4, 5AC and 5B. Exocytosis of secretory cells, recorded by videomicroscopy, showed that during swelling, the radius of the secretory granule matrix followed first-order kinetics. An increase in extracellular [Ca(2+)] from 1 to 4 mmol/l or a reduction in pH from 7.4 to 6.5 was seen to produce a significant decrease in the velocity of swelling of the secretory granule matrix.


CONCLUSIONS
The inverse relationship observed between the diffusion of the granular matrix and the extracellular [Ca(2+)] or [H(+)] suggested that changes in cation concentration might drastically affect the swelling characteristics of mucins and provide a control mechanism for the observed viscoelastic properties of mucus.
Espinosa
M
M
Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Unidad de Ginecología, Hospital Padre Hurtado, Santiago, Chile.
Noé
G
G
Troncoso
C
C
Ho
S B
SB
Villalón
M
M
D000143:Acids / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002584:Cervix Uteri / Q000166:cytology / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009077:Mucins / Q000502:physiology*; D009994:Osmolar Concentration; D022142:Secretory Vesicles / Q000502:physiology; D013997:Time Factors
D000143:Acids; D009077:Mucins; D002118:Calcium