Effects of VIP and PHM in human intracervical arteries

The relaxing effects of vasoactive intestinal polypeptide (VIP) and peptide histidine methionine (PHM) on human intracervical arteries were studied. Cervical tissue specimens were excised after hysterectomy at various phases of the menstrual cycle (n = 12) and small intracervical arteries were dissected free by microtechnique. Ring preparations of the vessels were prepared and mounted in organ baths, and isometric circular tension was recorded. None of the compounds showed any effects in unstimulated cervical arterial preparations. In vessels precontracted by noradrenalin 10(-5) M, VIP 10(-8) - 10(-6) M and PHM 10(-8) - 10(-6) M induced similar, concentration-dependent relaxation with a maximum effect of 73.2 +/- 12.7% relaxation for VIP 10(-6) M and 79.6 +/- 11.8% for PHM 10(-6) M, as compared to 10.7 +/- 3.1% decrease in tension for control preparations treated with solvent (mean +/- SE, n = 6). Simultaneous addition of VIP 5 x 10(-7) M and PHM 5 x 10(-7) M produced additive effects. Pretreatment with indometacin 10(-6) M, atropine 10(-6) M or propranolol 10(-6) M did not significantly influence these responses. Both peptides might be involved in regulation of blood flow in the human cervix.