Digital imaging of intracellular Ca2+ signaling in rat parotid acinar cells.
Utilizing digital imaging microscopy, the receptor-mediated changes in cytosolic Ca2+ concentration ([Ca2+]i) were studied in fura-2-loaded rat parotid acinar cells. The increase in [Ca2+]i induced by carbachol was initiated in the apical pole of the acinar cells and then spread as a Ca2+ wave toward the basolateral region. A similar polarization of Ca2+ signal was observed when the acinar cells were stimulated with substance P or phenylephrine. As the microsomal Ca2+-ATPase inhibitor thapsigargin did not produce a Ca2+ wave, activation of phosphoinositide hydrolysis is probably essential to trigger the Ca2+ wave. Stimulation with 1 microM isoproterenol, a concentration which causes the maximum release of amylase, had no effect on [Ca2+]i. Extracellular ATP (0.5 mM) induced a homogeneous increase in [Ca2+]i throughout the cells in the presence of extracellular Ca2+ but did not change [Ca2+]i in the absence of extracellular Ca2+, indicating that the ATP-induced rise in [Ca2+]i, is due to Ca2+ entry.
Tojyo
Y
Y
Department of Dental Pharmacology, School of Dentistry, Health Sciences University of Hokkaido, Japan.
Tanimura
A
A
Matsumoto
Y
Y
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007424:Intracellular Fluid / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008853:Microscopy / Q000379:methods; D018721:Muscarinic Agonists / Q000494:pharmacology; D010306:Parotid Gland / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
D000318:Adrenergic beta-Agonists; D018721:Muscarinic Agonists; D011943:Receptors, Adrenergic, beta; D000255:Adenosine Triphosphate; D002217:Carbachol; D007545:Isoproterenol; D002118:Calcium