Figure 4 - Secreted phospholipase A₂ (sPLA₂) inhibitors and [³H]AA release and LES tone.

a: LES muscle was incubated with [³H] arachidonic acid (3 Ci/mL), and then washed to remove unincorporated [³H]AA, and incubated in Krebs alone (control), AM5 or MJ33 (10^-4 M). [³H]AA release, an index of spontaneous PLA₂ activity, was significantly reduced by the nonselective sPLA₂ inhibitor AM5, and by the selective group I PLA₂ inhibitor MJ33. B: In LES muscle strips the group I PLA₂ inhibitor MJ33 decreased LES tone, and tetrodotoxin (10^-4 M) had no effect on the decrease. The cytosolic PLA₂ inhibitor AACOCF3 had no effect excluding involvement of cytosolic PLA₂. These data suggest that group I sPLA₂ may play a role in the maintenance of LES tone and that this PLA₂ may not come from nerve terminals. Values are means + SE of three to six animals.