Vasopressin has three main effects: 1  Increasing the water permeability of distal convoluted tubule and collecting duct cells in the kidney, thus allowing water reabsorption and excretion of more concentrated urine, i.e., antidiuresis.
It can be caused by damage to the vagus nerve, which regulates the digestive system. A damaged vagus nerve prevents the muscles in the stomach and intestine from functioning, preventing food from moving through the digestive system properly. Often, the cause of gastroparesis is unknown.
The valve is a muscle called the sphincter of Oddi. In rare cases, the sphincter of Oddi goes into spasm. It clamps shut and cannot relax. Other times it may be narrowed from previous inflammation. This is called sphincter of Oddi dysfunction (SOD). The condition causes intense belly pain. Your digestive juices back up into your pancreas and into the bile ducts of your liver. Another type of SOD happens when the sphincter of Oddi becomes stiff and narrow. This prevents digestive juices from entering your small intestine. Healthcare providers aren't sure why SOD happens.