Figure 3 - [³H]Arachidonic acid (AA) content and release of LES and esophageal circular smooth muscle.

LES circular muscle tissue was incubated for 4 hours in Krebs solution containing [³H] arachidonic acid (3 Ci/mL), to allow uptake into the muscle, then rinsed to remove unincorporated [³H]AA. After 60 minutes, the radioactivity released into the medium (b) was measured, and compared to the radioactivity present in tissue homogenates (a). Arachidonic acid levels were significantly higher in LES circular muscle than in esophageal circular muscle, which does not maintain tone, indicating a higher uptake of AA in LES muscle. LES circular muscle released significantly higher concentrations of AA than the esophagus, indicating a higher rate of metabolism of AA-containing phospholipids by the LES. Values are mean standard error (SE) of five to seven animals.