Binding of 125I-VIP to rat fundic muscular layer : radioautographic analysis of receptor distribution

To clarify the interaction of VIP to fundic motility, the binding of VIP to the rat fundus was studied by two kinds of microradioautographic procedures, i.e. radioautography of soluble compounds and in vitro radioautography using cryostat sections. Binding sites were seen on smooth muscle cells of the longitudinal layer and the interstitial cells near the myenteric plexus and the deep muscular plexuses as well as on nerve fibers between smooth muscle cells. Grains on the smooth muscle cells were dispersively recognized in the cytoplasm of r-ER-rich area, while the number of grains on the interstitial cells was significantly greater than that on the smooth muscle cells and heavily accumulated in the cytoplasm