Figure 2 - Signal transduction for LES tone.

From the following article

Signal transduction in lower esophageal sphincter circular muscle

Piero Biancani and Karen M. Harnett

GI Motility online (2006)



LES tone depends on activity of a group I secreted phospholipase A2 (sPLA2) producing arachidonic acid (AA), which is metabolized to prostaglandin F2alpha (PGF2alpha) and thromboxane A2 (TXA2). PGF2alpha and TXA2 may cross the cytoplasm and activate membrane receptors linked to Gq and Gi3. Gq activates phosphatidylinositol-specific phospholipase C (PI-PLC) to produce diacylglycerol (DAG) and IP3-induced Ca2+ release. Gi3 activates phosphatidylcholine-specific phospholipase C (PC-PLC) to produce DAG. Ca2+ and DAG activate PKCbeta resulting in phosphorylation of myosin light chain and contraction. (Source: Harnett et al.,3 with permission from the American Physiological Society.)

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