Open AccessCharacteristics of Ca2+ Oscillations in Ileal Longitudinal Muscle Cells of Guinea Pig
Author(s) -
Mitsutoshi Satoh,
Issei Takayanagi,
Kenichi Koike
Publication year - 2000
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.82.317
Subject(s) - cyclopiazonic acid , guinea pig , biophysics , intracellular , tetrodotoxin , chemistry , acetylcholine , medicine , basal (medicine) , endocrinology , biology , biochemistry , insulin
We studied the mechanisms and characteristics of the spontaneously evoked intracellular Ca2+ changes (Ca2+ oscillations) in ileal longitudinal smooth muscle from guinea pig. Two-dimensional images of Ca2+ oscillations were obtained at 33-ms intervals with a Ca2+-sensitive fluorescence probe, fluo-3 using the intensified CCD camera. Nicardipine (10-7 M) significantly decreased the maximum level of fluorescence intensity of the Ca2+ oscillations, inhibited the frequency of the oscillations and tended to decrease the basal level of fluorescence intensity. However, tetrodotoxin (3 x 10-7 M) did not affect these oscillations. Phorbol 12,13-dibutyrate (10-7 M) significantly increased the maximum level of fluorescence intensity and the frequency of Ca2+ oscillations, and it changed them to steady and chronometric Ca2+ oscillations. Cyclopiazonic acid (3 x 10-5 M) also significantly increased the frequency of Ca2+ oscillations. Acetylcholine (10-8 M) increased the basal and maximum level of fluorescence intensity and the frequency of Ca2+ oscillations, and accelerated their onset. The increase of basal level of fluorescence intensity was then decreased by cyclopiazonic acid treatment. These results suggest that the augmentation of Ca2+ oscillations is mainly due to the activation of L-type Ca2+ channels, which is modulated by protein kinase C, and that the emptying of intracellular Ca2+ stores may activate the Ca2+ oscillations mediated through the increase of Ca2+ influx in ileal smooth muscle of guinea pig.