Maturation of cholecystokinin receptors in pancreatic acini of rats.

Amylase secretion by fetal and newborn rat pancreata was shown not to respond to cholecystokinin (CCK) stimulation. Binding of 125I-Bolton-Hunter (125I-BH)-CCK-8 to dispersed pancreatic acini from rats at various perinatal ages was measured and compared with adults. Binding occurred maximally at 30 min at 37 degrees C at all ages. Maximal binding increased with age. The capacity and affinity of the CCK-receptor binding system was analyzed by Scatchard's method. The results revealed that the capacity of the high-affinity component gradually increases with age, whereas that of the low-affinity component remains relatively constant. Amylase secretion due to CCK stimulation also increases with age, suggesting that the lack of responsiveness of pancreata of pups to secretagogue is due to a low binding capacity of the high-affinity component of the receptors.