CCK and digestive system disorder: CCK also plays a key role in cholelithiasis and gallbladder diseases, affecting the emptying of the gallbladder and the function of the biliary system through its effect on the smooth muscle of the gallbladder.545 Thus, CCK receptor (primarily CCK1 receptor) antagonists are being investigated as potential agents for the treatment of cholelithiasis, gallbladder disease, and certain gastrointestinal disorders.