In vitro investigation of the effects of nonsteroidal anti-inflammatory drugs, prostaglandin E2, and prostaglandin F2α on contractile activity of the third compartment of the stomach of llamas

Objective —To determine the in vitro effect of prostaglandin (PG) E 2 , PGF 2α , and the nonsteroidal anti-inflammatory drugs (NSAIDs) indomethacin, ketoprofen, and nabumetone on the contractile strength of the circular smooth muscle layer of the third compartment of the stomach of llamas. Sample Population —Specimens of the third compartment obtained from 5 healthy adult llamas. Procedure —Full-thickness tissue samples were collected from the third compartment immediately after euthanasia. Specimens were cut into strips oriented along the circular muscle layer and mounted in a tissue bath system. Incremental amounts of ketoprofen, nabumetone, indomethacin, PGE 2 , and PGF 2α were added, and contractile strength (amplitude of contractions) was recorded. Results —Generally, PGE 2 reduced contractile strength of the circular smooth layer of the third compartment, whereas PGF 2α increased the strength of contractions. The activity of the NSAIDs was generally excitatory in a concentration-dependent manner, although significant changes were induced only by administration of indomethacin. Conclusions and Clinical Relevance —On isolated smooth muscle strips of the third compartment of llamas, exogenous PGE 2 and PGF 2α had a variable effect on contractile strength. Administration of the NSAIDs did not inhibit contractility and would not be likely to induce stasis of the third compartment in the absence of an underlying disease process. ( Am J Vet Res 2004;65:220–224