In the study, researchers created GERD in rats by connecting the duodenum to the esophagus. This operation allows stomach acid and bile to enter the esophagus. Researchers were surprised to learn that esophagitis didn't develop for a number of weeks after the operation.
"That doesn't make sense if GERD is really the result of an acid burn, as we all were taught in medical school," said Dr. Stuart Spechler, professor of internal medicine at UT Southwestern and senior author of the study. "Chemical injuries develop immediately. If you spill battery acid on your hand, you don't have to wait a month to see the damage."
Previous studies had shown that if an animal esophagus is perfused with highly concentrated acid, esophageal damage develops quickly. In humans, however, the large majority of reflux episodes do not contain such highly concentrated acid, Dr. Souza said.
Dr. Souza, who is also a staff physician at the Dallas Veterans Affairs Medical Center and part of the Harold C. Simmons Comprehensive Cancer Center at UT Southwestern, and Dr. Spechler, chief of gastroenterology at the Dallas VA, said the method they used to produce GERD in rats is a reasonable representation of how GERD develops in humans -- acidic digestive juices from the stomach surge into the esophagus.
Soon after the operation, they expected to see the death of surface cells of the esophagus, and they expected to see the injury progress later to the deeper layers. Instead, they found the opposite. Three days after the surgery, there was no damage to surface cells, but the researchers did find inflammatory cells in the deeper layers of the esophagus. Those inflammatory cells didn't rise to the surface layer until three weeks after the initial acid exposure.
The study was supported by the Dallas VA Medical Center and the National Institutes of Health.
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