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Pharmacological evidences for the stimulation of calcium-sensing receptors by nifedipine in gingival fibroblasts.

Hattori T, Ara T, Fujinami Y - J Pharmacol Pharmacother (2011)

Bottom Line: This confirmed the pathway components mediating Ca(2+) responses to a known agonist of the CaSR.Calphostin C (a PKC inhibitor) and TMB-8 (an inhibitor of Ca(2+) release from stores) also inhibited the nifedipine-induced [Ca(2+)] i elevation.These findings suggest that CaSRs are involved in the nifedipine-induced [Ca(2+)] i elevation in gingival fibroblasts.

View Article: PubMed Central - PubMed

Affiliation: Department of Dental Pharmacology, Matsumoto Dental University, Shiojiri 399-0781, Japan.

ABSTRACT

Objective: To investigate pharmacologically whether CaSRs are involved in the Ca(2+) antagonist-induced [Ca(2+)]i elevation in gingival fibroblasts.

Materials and methods: Gin-1 cells, normal human gingival fibroblasts, were used as the material. The [Ca(2+)] i was measured with fura-2/AM, a Ca(2+)-sensitive fluorescent dye.

Results: At first, we confirmed the existence of CaSRs in these cells by showing that [Ca(2+)] i was elevated by high concentrations of extracellular Ca(2+) and by prototypic agonists of the CaSR such as gentamicin. The action of gentamicin was antagonized by inhibitors of phospholipase C (PLC), inositol trisphosphate (IP(3)) receptors, NSCCs, and, importantly, by the CaSR antagonist, NPS2390. Furthermore, the action of gentamicin was potentiated by activators of PLC and protein kinase C (PKC). This confirmed the pathway components mediating Ca(2+) responses to a known agonist of the CaSR. We then investigated whether nifedipine (an L-type Ca(2+) channel blocker) stimulates CaSRs to elevate [Ca(2+)] i via a similar mechanism. Nifedipine Ca(2+) responses were dose-dependently blocked by NPS2390 and by the same inhibitors of PLC, IP(3) receptors, and NSCCs that disrupted the action of gentamicin. Calphostin C (a PKC inhibitor) and TMB-8 (an inhibitor of Ca(2+) release from stores) also inhibited the nifedipine-induced [Ca(2+)] i elevation.

Conclusion: These findings suggest that CaSRs are involved in the nifedipine-induced [Ca(2+)] i elevation in gingival fibroblasts.

No MeSH data available.


Related in: MedlinePlus

Elevation of the [Ca2+]i by calcium-sensing receptor agonists. Intracellular Ca2+ measurements were made in the presence (hatched bars) or absence (clear bars) of various compounds: gentamicin (500 µM), neomycin (300 µM), spermine (3 mM), LaCl3 (10 µM), and verapamil (25 µM). The upper trace shows a representative time course of the [Ca2+]i in the case of gentamicin application. Data are mean ± SEM, N = 32 (gentamicin, neomycin, spermine), 25 (LaCl3), or 20 (verapamil). ****P < 0.001compare to corresponding pretreated values
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Figure 0002: Elevation of the [Ca2+]i by calcium-sensing receptor agonists. Intracellular Ca2+ measurements were made in the presence (hatched bars) or absence (clear bars) of various compounds: gentamicin (500 µM), neomycin (300 µM), spermine (3 mM), LaCl3 (10 µM), and verapamil (25 µM). The upper trace shows a representative time course of the [Ca2+]i in the case of gentamicin application. Data are mean ± SEM, N = 32 (gentamicin, neomycin, spermine), 25 (LaCl3), or 20 (verapamil). ****P < 0.001compare to corresponding pretreated values

Mentions: As shown in Figure 2, the CaSR agonists gentamicin (500 µM), neomycin (300 µM), spermine (3 mM), lanthanum chloride (LaCl3; 10 µM), and verapamil (25 µM) all significantly raised [Ca2+]i. We further tested the concentration-dependence of the response to verapamil. Increasing concentrations of verapamil (1, 5, and 25 µM) induced progressively larger [Ca2+]i elevations above basal (4.20 ± 1.01 nM; 9.65 ± 1.04 nM; and 33.6 ± 3.30 nM, respectively; P < 0.001 for all concentrations; N = 20 in each case). This demonstrates that known CaSR agonists mediate intracellular Ca2+ signaling in normal human gingival fibroblast Gin-1 cells.


Pharmacological evidences for the stimulation of calcium-sensing receptors by nifedipine in gingival fibroblasts.

Hattori T, Ara T, Fujinami Y - J Pharmacol Pharmacother (2011)

Elevation of the [Ca2+]i by calcium-sensing receptor agonists. Intracellular Ca2+ measurements were made in the presence (hatched bars) or absence (clear bars) of various compounds: gentamicin (500 µM), neomycin (300 µM), spermine (3 mM), LaCl3 (10 µM), and verapamil (25 µM). The upper trace shows a representative time course of the [Ca2+]i in the case of gentamicin application. Data are mean ± SEM, N = 32 (gentamicin, neomycin, spermine), 25 (LaCl3), or 20 (verapamil). ****P < 0.001compare to corresponding pretreated values
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3117567&req=5

Figure 0002: Elevation of the [Ca2+]i by calcium-sensing receptor agonists. Intracellular Ca2+ measurements were made in the presence (hatched bars) or absence (clear bars) of various compounds: gentamicin (500 µM), neomycin (300 µM), spermine (3 mM), LaCl3 (10 µM), and verapamil (25 µM). The upper trace shows a representative time course of the [Ca2+]i in the case of gentamicin application. Data are mean ± SEM, N = 32 (gentamicin, neomycin, spermine), 25 (LaCl3), or 20 (verapamil). ****P < 0.001compare to corresponding pretreated values
Mentions: As shown in Figure 2, the CaSR agonists gentamicin (500 µM), neomycin (300 µM), spermine (3 mM), lanthanum chloride (LaCl3; 10 µM), and verapamil (25 µM) all significantly raised [Ca2+]i. We further tested the concentration-dependence of the response to verapamil. Increasing concentrations of verapamil (1, 5, and 25 µM) induced progressively larger [Ca2+]i elevations above basal (4.20 ± 1.01 nM; 9.65 ± 1.04 nM; and 33.6 ± 3.30 nM, respectively; P < 0.001 for all concentrations; N = 20 in each case). This demonstrates that known CaSR agonists mediate intracellular Ca2+ signaling in normal human gingival fibroblast Gin-1 cells.

Bottom Line: This confirmed the pathway components mediating Ca(2+) responses to a known agonist of the CaSR.Calphostin C (a PKC inhibitor) and TMB-8 (an inhibitor of Ca(2+) release from stores) also inhibited the nifedipine-induced [Ca(2+)] i elevation.These findings suggest that CaSRs are involved in the nifedipine-induced [Ca(2+)] i elevation in gingival fibroblasts.

View Article: PubMed Central - PubMed

Affiliation: Department of Dental Pharmacology, Matsumoto Dental University, Shiojiri 399-0781, Japan.

ABSTRACT

Objective: To investigate pharmacologically whether CaSRs are involved in the Ca(2+) antagonist-induced [Ca(2+)]i elevation in gingival fibroblasts.

Materials and methods: Gin-1 cells, normal human gingival fibroblasts, were used as the material. The [Ca(2+)] i was measured with fura-2/AM, a Ca(2+)-sensitive fluorescent dye.

Results: At first, we confirmed the existence of CaSRs in these cells by showing that [Ca(2+)] i was elevated by high concentrations of extracellular Ca(2+) and by prototypic agonists of the CaSR such as gentamicin. The action of gentamicin was antagonized by inhibitors of phospholipase C (PLC), inositol trisphosphate (IP(3)) receptors, NSCCs, and, importantly, by the CaSR antagonist, NPS2390. Furthermore, the action of gentamicin was potentiated by activators of PLC and protein kinase C (PKC). This confirmed the pathway components mediating Ca(2+) responses to a known agonist of the CaSR. We then investigated whether nifedipine (an L-type Ca(2+) channel blocker) stimulates CaSRs to elevate [Ca(2+)] i via a similar mechanism. Nifedipine Ca(2+) responses were dose-dependently blocked by NPS2390 and by the same inhibitors of PLC, IP(3) receptors, and NSCCs that disrupted the action of gentamicin. Calphostin C (a PKC inhibitor) and TMB-8 (an inhibitor of Ca(2+) release from stores) also inhibited the nifedipine-induced [Ca(2+)] i elevation.

Conclusion: These findings suggest that CaSRs are involved in the nifedipine-induced [Ca(2+)] i elevation in gingival fibroblasts.

No MeSH data available.


Related in: MedlinePlus