Responsiveness of beta-escin-permeabilized rabbit gastric gland model: effects of functional peptide fragments

We established a beta-escin-permeabilized gland model with the use of rabbi t isolated gastric glands. The glands retained an ability to secrete acid, monitored by [C-14]aminopyrine accumulation, in response to cAMP, forskolin , and histamine. These responses were all inhibited by cAMP-dependent prote in kinase inhibitory peptide. Myosin light-chain kinase inhibitory peptide also suppressed aminopyrine accumulation, whereas the inhibitory peptide of protein kinase C or that of calmodulin kinase II was without effect. Guano sine-5'-O-(3-thiotriphosphate (GTP gamma S) abolished cAMP-stimulated acid secretion concomitantly, interfering with the redistribution of H+-K+-ATPas e from tubulovesicles to the apical membrane. To identify the targets of GT P gamma S, effects of peptide fragments of certain GTP-binding proteins wer e examined. Although none of the peptides related to Rab proteins showed an y effect, the inhibitory peptide of Arf protein inhibited cAMP-stimulated s ecretion. These results demonstrate that our new model, the beta-escin-perm eabilized gland, allows the introduction of relatively large molecules, e.g ., peptides, into the cell, and will be quite useful for analyzing signal t ransduction of parietal cell function.