Culture of normal and inflamed rabbit colonic explants. Medium-term prostaglandin profile

Rabbit colonic biopsy specimens cultured under well-standardized conditions showed a linear uptake of leucine, thymidine and arachidonic acid (AA) for at least 48 h. Prostaglandin E2 (PGE2) production displayed a time-dependent profile. Initial high and fluctuating levels were seen as a result of the preparation trauma. Within 5-7 h a semi-steady state was reached. Addition of the Ca++ ionophore A23187 significantly increased PGE2 production throughout the 48-h time course, but stimulation was optimal (fivefold) around 6 h, as compared with two- to three-fold at 24 and 48 h. Phorbol 12-myristate 13-acetate stimulation of biopsy specimens labelled for 24 h with 14C-AA showed significantly higher proportional release of 14C-PGE2 than after A23187 or a combination of both, indicating stimulus utilization of different AA pools, with variable turnover. Mucosa from rabbits with acetic acid-induced colitis demonstrated a significantly increased leucine incorporation during the first 24-h period and normal incorporation during the second period. PGE2 production reached a high A23187-insensitive maximum at 24 h. This study shows the importance of sample timing, the existence of different AA pools, and the feasibility of studying inflamed mucosa in medium-term tissue culture.