A GUINEA-PIG MODEL FOR STUDY OF BLADDER MAST-CELL FUNCTION - HISTAMINE-RELEASE AND SMOOTH-MUSCLE CONTRACTION

To study the function of mast cells in bladder tissue, guinea pigs were sensitized with ovalbumin by intraperitoneal injections, bladder tissue strips were superfused, and tissue contractile force and histamine release were studied. Upon challenge with ovalbumin, bladder tissue contracted 64 ± 4% (mean ± S.E.M.) of the maximum carbachol contraction and released 14.1 ± 1.6% of the total tissue histamine content. Incubation of sensitized bladder tissue with indomethacin led to an increased force and duration of the contraction while incubation with nordihydroguaiaretic acid combined with pyrilamine reduced histamine release and abolished the contraction. Tissue histamine content was significantly higher in the bladder neck than in the dome, and significantly elevated following sensitization. Histochemical studies of bladder tissue demonstrated mast cell degranulation in antigen challenge experiments. In addition, a group of guinea pigs were sensitized to ovalbumin through bladder instillations. With this model, study of the functional characteristics of bladder mast cells and the acute actions of mast cell products on the bladder microenvironment, should now be feasible.