Modulation of rat incisor odontoblast plasma membrane-associated Ca2+ with nifedipine.
In addition to the Ca2+ portion freely dissociated in the cytosol, another Ca2+ pool is associated with plasma membranes and intracellular organelle membranes. This Ca2+ portion is of importance for regulation of, among other things, the cell cycle, actin-mediated processes, and cell morphology. In the literature, dihydropyridines have been reported to influence this membrane-associated pool of Ca2+ under certain conditions. The aim of this investigation was to study possible modulations of plasma membrane-associated Ca2+ upon treatment with nifedipine in vitro in a Ca2+-transporting cell, the dentin-forming odontoblast. The membrane-associated portion of Ca2+ in dissected dentinogenically active rat incisor odontoblasts was monitored by fluorescence spectrophotometry using chlortetracycline as a probe. In addition, images of chlortetracycline-Ca2+ binding were obtained by fluorescence microscopy. It was found that membrane-associated Ca2+ decreased by the dihydropyridine nifedipine, whereas this Ca2+ pool was unaffected by the cellular polarization state, which was in contrast to cytosolic free Ca2+ as measured by fura-2. The results show that the odontoblast plasma membrane-associated Ca2+-pool can be modulated by nifedipine, thus being dependent on the conformational state of the L-type Ca2+ channels.
Lundgren
T
T
Department of Oral Biochemistry, Faculty of Odontology, Göteborg University, P.O. Box 451, S-405 30 Göteborg, Sweden. lundgren@odontologi.gu.se
Linde
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry*; D002751:Chlortetracycline / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D016257:Fura-2 / Q000378:metabolism; D007180:Incisor / Q000187:drug effects*; D008856:Microscopy, Fluorescence; D009543:Nifedipine / Q000494:pharmacology*; D009804:Odontoblasts / Q000166:cytology / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
D015220:Calcium Channels; D005456:Fluorescent Dyes; D009543:Nifedipine; D002118:Calcium; D016257:Fura-2; D002751:Chlortetracycline