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Receptor‐coupled shortening of α‐toxin‐permeabilized single smooth muscle cells from the guinea‐pig stomach
Author(s) -
Ono Teruaki,
Mita Mitsuo,
Suga Osamu,
Hashimoto Takao,
Oishi Kazuhiko,
Uchida Masaatsu K.
Publication year - 1992
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1992.tb14371.x
Subject(s) - inositol , muscarinic acetylcholine receptor , acetylcholine , receptor , guanosine , biology , stimulation , gtp' , medicine , biophysics , endocrinology , guanosine triphosphate , muscle contraction , chemistry , biochemistry , enzyme
1 Isolated single smooth muscle cells from the fundus of the guinea‐pig stomach were permeabilized by use of Staphylococcus aureus α ‐toxin. Receptor‐coupled shortening of individual cells was monitored under phase contrast microscopy. 2 Most of the isolated cells responded to 0.6 μ m Ca 2+ , but not to 0.3 μ m Ca 2+ , with a resulting maximal shortening to approximately 65% of the resting cell length. The contractile activity of these permeabilized cells lasted for several hours and repeated shortening was readily achieved after washing out. 3 Addition of acetylcholine (ACh) at a maximal concentration (10 μ m ) resulted in a marked decrease in the concentration of Ca 2+ required to trigger a threshold response from 0.6 μ m to 0.2 μ m , and 1 m m guanosine 5′‐diphosphate (GDP) blocked this decrease. Moreover, treatment with 100 μ m guanosine 5′‐triphosphate (GTP) mimicked the action of ACh. 4 Addition of 100 μ m inositol 1,4,5‐trisphosphate (InsP 3 ) with 0.2 μ m Ca 2+ did not cause cell shortening, whereas 10 μ m ACh with 0.2 μ m Ca 2+ did, suggesting that InsP 3 ‐induced Ca 2+ release is not involved in ACh‐operated cell shortening. 5 The present study demonstrates an α‐toxin‐permeabilized single smooth muscle cell preparation which retains its receptor function and also provides an insight into mechanisms leading to augmentation of Ca 2+ sensitivity by stimulation of muscarinic receptors or GTP‐binding proteins.