Potentiation by stannous chloride of calcium entry into osteoblastic MC3T3-E1 cells through voltage-dependent L-type calcium channels.
The present study was undertaken to confirm that L-type Ca(2+) channels are involved in Ca(2+) entry into osteoblastic MC3T3-E1 cells and to examine the effect of SnCl2, a Ca(2+)]-channel activator, on the intracellular Ca(2+)concentration ([Ca(2+)]i). High K(+)concentration-dependently raised the [Ca(2+)]i. All of the L-type Ca(2+)channel blockers used here, such as nifedipine, nicardipine, verapamil, and diltiazem, and CdCl2 (a non-selective blocker) inhibited the high K(+)-induced [Ca(2+)]i rise, but v-conotoxin GVIA (an N-type blocker) and NiCl2(a T-type blocker) had no effect. Application of SnCl2 alone did not change the [Ca(2+)]i. However, in the presence of high K(+), SnCl2 enhanced the high K(+)-induced [Ca(2+)]i rise, which was inhibited by Ca(2+)]-free medium or nifedipine. In the case where high K(+)was applied prior to SnCl2, SnCl2 alone raised the [Ca(2+)]i by itself. In conclusion, MC3T3-E1 cells possess the voltage-dependent L-type Ca(2+)] channels and SnCl2 facilitates the Ca(2+) entry through the L-type ones under the condition of the membrane depolarization. There is the possibility that Ca(2+) release from intracellular Ca(2+) stores is involved in the action of SnCl2.
Hattori
T
T
Department of Dental Pharmacology, Matsumoto Dental University, Shiojiri, Japan. hattori@po.mdu.ac.jp
Maehashi
H
H
Miyazawa
T
T
Naito
M
M
D016475:3T3 Cells; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000502:physiology*; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D002460:Cell Line; D004357:Drug Synergism; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism* / Q000502:physiology; D011189:Potassium Chloride / Q000494:pharmacology; D017971:Tin Compounds / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D017971:Tin Compounds; C023599:stannous chloride; D011189:Potassium Chloride