Intercellular communication between dorsal root ganglion cells end colonic smooth muscle cells in vitro

THE mechanism(s) by which intestinal smooth muscle tension is signaled to extrinsic primary afferent neurons is poorly understood. In order to characterize myocyte-neuron communication, we developed a coculture system using rat dorsal root ganglion (DRG) neurons and myocytes obtained from the circular muscle layer of the rat distal colon. Both cell types maintained their phenotype in culture, as demonstrated by positive immunocytochemical staining for neuron-specific enolase and smooth muscle actin. Myocytes showed mechanosensitivity in the form of increases in [Ca2+](i) in response to light mechanical touch of the plasma membrane. This increase in [Ca2+](i) was independent of extracellular Ca2+ and passed as a propagated wave from muscle cells into adjacent DRG neurites. The inhibitory effect of octanol on this intercellular propagation suggests propagation of [Ca2+](i) gradients via heterologous gap junctions. This preparation may serve a useful model system for the study of the interaction of visceral afferents and their target cells.