Epidermal growth factor (EGF) has been tested on guinea pig gastric mucosa mounted in Ussing chambers to investigate the suitability of using in vitro methods for examining EGF's effects on acid secretion. Epidermal growth factor reduced the rate of histamine-induced acid secretion to near basal levels when applied to the serosal gastric surface at nanomolar concentrations. Inhibitory effects were evident 10-15 min after EGF treatment and were maximal by 40 min. Cyclic adenosine monophosphate-induced secretion was also reduced by EGF, although the effect occurred more slowly than in histamine-treated tissues. Epidermal growth factor increased transmucosal resistance in histaminetreated, but not cyclic adenosine monophosphatetreated mucosa; potential difference was unaffected. Nerve growth factor had no effect when tested in the in vitro system. The EGF binding protein was found to enhance slightly the inhibitory activity of EGF on acid secretion. When applied to the luminal (mucosal) gastric surface, EGF inhibited secretion marginally but only at micromolar concentrations. These results indicate that EGF acts directly upon cells within the gastric mucosa, and is most effective when applied to the serosal gastric surface. They further suggest that in vitro preparations of intact gastric mucosa can be used for analyzing the inhibitory effects of EGF on gastric acid secretion.
- cyclic adenosine monophosphate
- epidermal growth factor
- highmolecular-weight epidermal growth factor
- nerve growth factor
- potential difference
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