Responsiveness of [Beta]-escin-permeabilized rabbit gastric gland model: effects of functional peptide fragments

Akagi, Keiko, Taku Nagao, and Tetsuro Urushidani. Responsiveness of [Beta]-escin-permeabilized rabbit gastric gland model: effects of functional peptide fragments. Am. J. Physiol. 277 (Gastrointest. Liver Physiol. 40): G736-G744, 1999.--We established a [Beta]-escin-permeabilized gland model with the use of rabbit isolated gastric glands. The glands retained an ability to secrete acid, monitored by [[sup.14]C] aminopyrine accumulation, in response to cAMP, forskolin, and histamine. These responses were all inhibited by cAMP-dependent protein 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. Guanosine-5'-O-(3-thiotriphosphate) (GTP[Gamma]S) abolished cAMP-stimulated acid secretion concomitantly, interfering with the redistribution of [H.sup.+]-[K.sup.+]-ATPase from tubulovesicles to the apical membrane. To identify the targets of GTP[Gamma]S, effects of peptide fragments of certain GTP-binding proteins were examined. Although none of the peptides related to Rab proteins showed any effect, the inhibitory peptide of Arf protein inhibited cAMP-stimulated secretion. These results demonstrate that our new model, the [Beta]-escin-permeabilized gland, allows the introduction of relatively large molecules, e.g., peptides, into the cell, and will be quite useful for analyzing signal transduction of parietal cell function. parietal cell; acid secretion; small GTP-binding protein; protein kinases