COLOMBO, M.J.; VATNICK, I.; BRODKIN, M.A.; ANDREWS, J.L.; PIDDINGTON, E.J.; FIORINI, E.; RAMESWARAN, M.; WIDENER UNIVERSITY; WIDENER UNIVERSITY; WIDENER UNIVERSITY; WIDENER UNIVERSITY; WIDENER UNIVERSITY; WIDENER UNIVERSITY: Acid Stress Suppresses The Thioglycollate-Stimulated Inflammatory Response of Adult Rana pipiens

Acidic environments function as a stressor for amphibians. Previous work in our lab showed that adult ranid frogs exhibit different levels of tolerance to mild acid conditions (pH 5.5). Adult Rana pipiens are more susceptible than other ranids and experienced 65% mortality after ten day exposure to pH 5.5. We also demonstrated that acid exposure increases the permeability of the gut to the endogenous bacterial flora and results in a systemic infection. Inflammation is a natural protective defense against microbial infection, characterized by an influx of leukocytes to the site of infection. Thioglycollate medium is used experimentally to stimulate an inflammatory response in several vertebrates. In frogs, intraperitoneal injection of thioglycollate causes an influx of peritoneal exudates containing leukocytes. Our study shows that acid exposure (pH 5.5) greatly suppresses the inflammatory response in thioglycollate-induced R. pipiens. The number of leukocytes as well as their phagocytic efficiency was significantly reduced in acid-exposed thioglycollate-induced adult R. pipiens as compared to their controls. Frogs induced by thioglycollate injection and exposed to pH 5.5 had a 50% increase in cells that did not exhibit phagocytosis and a four-fold reduction in the number of highly efficient phagocytic cells.