PEPTIDE HISTIDINE VALINE (PHV) IS PRESENT AND BIOLOGICALLY-ACTIVE IN THE HUMAN FEMALE GENITAL-TRACT

The occurrence of vasoactive intestinal polypeptide (VIP), peptide his tidine methionine (PHM) and peptide histidine valine (PHV) in the huma n female genital tract was studied by means of radioimmunoassay in com bination with gel chromatography. In addition, the effect of PHV on ge nital smooth muscle activity was investigated and compared to that of VIP. Immunoreactive VIP, PHM and PHV were present in all regions of th e human female genital tract, the highest concentrations being measure d in the vagina and the uterine cervix. The peptides displayed similar regional distribution and as expected from the structure of the VIP p recursor molecule in which the examined peptides are contained, the mo lar ratio of VIP to the total PHM/PHV immunoreactivity was close to 1: 1. In all regions PHV constituted 50-70% of the total PHM/PHV immunore activity indicating that the dibasic conversion site after PHM was unc leaved. VIP and PHV were found to be equipotent relaxants of the smoot h muscle from the Fallopian tube and the myometrium. The present study indicates that PHV like PHM and VIP may act as a neurotransmitter in the human female genital tract and thus participate in the local nervo us control of the reproductive functions.