1. Analytical subcellular fractionation techniques have been applied to endoscopic human gastric antral biopsies to study the localization of gastrin, somatostatin, vasoactive intestinal peptide and the properties of the principal subcellular organelles.
2. The peptide hormones, detected by radio-immunoassay, showed particulate localizations with single peaks in the density gradients for somatostatin (modal density 1.23) and vasoactive intestinal peptide (modal density 1.17). Gastrin showed a more complex distribution with a distinct peak (modal density 1.18) and a substantial shoulder extending into the denser regions of the gradient.
3. The following organelles, characterized by their marker enzymes, were located in the density gradients: plasma membrane (5′-nucleotidase), mitochondria (malate dehydrogenase), peroxisomes (catalase), lysosomes ((β-N-acetyl-d-glucosaminidase), endoplasmic reticulum (neutral α-glucosidase), cytosol (lactate dehydrogenase).
4. This technique can be applied to investigate disease of the gastric antrum at a subcellular level.