Ca2+ entry through the store-mediated pathway directly activates only the K+ current but the subsequent Ca2+ release from the store activates both K+ and Cl- currents in submandibular gland acinar cells of the rat.
The store-mediated Ca2+ entry was detected in single and cluster of rat submandibular acinar cells by measuring the Ca2+ activated ionic membrane currents. In the cells where intracellular Ca2+ was partly depleted by stimulation with submaximal concentration of acetylcholine (ACh) under a Ca2(+)-free extracellular condition, an employment of external Ca2+ in the absence of ACh caused a sustained increase of the K+ current without affecting the Cl- current. A renewed ACh challenge without external Ca2+ caused repetitive spikes of both K+ and Cl- currents due to the Ca2+ release. SK & F 96365 inhibited the generation of the sustained K+ current and refilling of the Ca2+ store following the Ca2+ readmission. It is suggested that the Ca2+ enters the cell through the store-mediated pathway new the K+ channels and is taken up by the store. Thus, only Ca2+ released from the store can activate both the K+ and Cl- currents.
Wakui
M
M
Department of Physiology, Hirosaki University School of Medicine, Japan.
Wada
J
J
Kamimura
N
N
Mio
Y
Y
Sasaki
T
T
Fukushi
Y
Y
Nishiyama
A
A
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D002451:Cell Compartmentation; D002712:Chlorides / Q000378:metabolism*; D007093:Imidazoles / Q000494:pharmacology*; D007295:Inositol Phosphates / Q000378:metabolism; D009543:Nifedipine / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D013363:Submandibular Gland / Q000187:drug effects / Q000378:metabolism*
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002712:Chlorides; D007093:Imidazoles; D007295:Inositol Phosphates; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D009543:Nifedipine; D000109:Acetylcholine; D011188:Potassium; D002118:Calcium