Uptake and secretion of technetium pertechnetate by the rat parotid gland

The ability of acinar cells of the rat parotid gland to transport technetium pertechnetate (99mTcO-4) was examined. After intravenous injection, 99mTcO-4 was rapidly detected in parotid saliva. There was an excellent correlation between saliva and plasma 99mTcO-4 levels. The saliva to plasma ratio was always less than 1, consistent with the inability of rat parotid gland duct cells to concentrate the anion. Output of 99mTcO-4 by the parotid gland closely mimicked fluctuations in parotid saliva flow rate. In vitro, enzymatically dispersed parotid acinar cells accumulated 99mTcO-4 from the incubation medium in a biphasic manner. This uptake was partially blocked by 10(-4) M NaI. Cells which had accumulated 99mTcO-4 showed increased radionuclide efflux after exposure to 10(-5) M carbachol.