Diffusion rates of vasopressin through human vaginal and buccal mucosa

The permeability to several chemical compounds and the histology of vaginal and buccal mucosa are very similar. Because vaginal mucosa is more abundant, it may be used as a model for the latter. To further develop the vaginal/buccal mucosa model, the objective of the present study was to evaluate the passage of a small polypeptide, vasopressin, across fresh and frozen specimens of these two mucosae. Specimens of fresh buccal and vaginal mucosa were taken from excised tissue obtained following vaginal hysterectomies and various oral surgical procedures. Pieces of buccal and vaginal tissue specimens obtained were used fresh or were snap-frozen and stored at -85 degrees C for periods of up to 10 months. Biopsies from fresh and thawed specimens were mounted in flow-through diffusion cells and their permeability to tritiated vasopressin was determined using a continuous flow-through perfusion system. Specimens were examined histologically before and after freezing as well as before and after permeability experiments and similarities between vaginal and buccal tissues verified. No statistically significant differences between flux values for fresh and frozen vaginal and buccal mucosa, respectively, were found. These results demonstrate that the permeation of vasopressin across fresh and frozen human vaginal and buccal mucosa is for practical purposes similar. These results further support the human vaginal/buccal mucosa model for in vitro permeability studies on therapeutically active compounds.