Toward a Concept of Stretch Coupling in Smooth Muscle: A Thesis by Lars Thuneberg on Contractile Activity in Neonatal Interstitial Cells of Cajal

The hypothesis was put forward by Thuneberg that rhythmically contracting interstitial cells of Cajal (ICC) were sensing stretch of the musculature and that this information was transmitted to smooth muscle cells via peg and socket contacts. The present study provides the evidence for the contractile nature of ICC as perceived by Thuneberg. The contractile activity is shown by video frame subtraction and by tracking areas of interest in sequential video frames. Thuneberg used neonatal ICC in culture maintained between two coverslips thereby allowing growth factors to quickly reach optimal concentrations. Contractions of ICC were seen to precede smooth muscle contractions. In addition, strong contractions were observed solely in branches of ICC. It is hoped that this communication will stimulate discussion about the contractile nature of ICC and that this phenomenon will eventually find its place amongst the physiological properties of the ICC networks of the gut musculature.