Culture of Normal and Inflamed Rabbit Colonic Explants

Abstract

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 ^l4C-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.

Key Words:

• A23187
• arachidonic acid
• inflammation
• organ culture
• phorbol 12-myristate 13-acetate
• prostaglandin E₂