Identification of glucagon binding sites on smooth muscle tissue of dog intestine. Quantification by means of ultrastructural autoradiography.

125I-glucagon binding sites have been detected and quantified on the intestinal smooth muscle cells of the dog by means of ultrastructural autoradiographic methods. These binding sites are located mainly in the plasmalema. The present findings established a morphological correlation with the physiological data concerning the spasmolytic function of the glucagon on the intestinal wall.