Histochemical localization of vasoactive intestinal polypeptide and its influence on contractile activity in the non-pregnant and pregnant human cervix.

The distribution of vasoactive intestinal peptide (VIP) was studied by immunofluorescence in cervical tissue of non-pregnant and pregnant women. VIP was localized in connection with blood vessels as well as among collagen fibres and smooth muscle cells. No difference was observed between non-pregnant and term pregnant women. The effect of VIP on cervical contractility was tested on isolated strips by superfusion in a tissue chamber. VIP inhibited contractions at 10(-8)-10(-6) M concentration, strips from term pregnant women responding more frequently at the lower concentration. It is suggested that VIP-containing neurons of the human cervix remain intact throughout pregnancy until term.