Activation of dihydropyridine sensitive Ca2+ channels in rat hippocampal neurons in culture by parathyroid hormone.
We examined the effects of parathyroid hormone (PTH) on rat hippocampal neurons in culture to determine whether it caused a similar intracellular calcium concentration ([Ca2+]i) increase in these cells to that seen with renal epithelial cells and found that PTH induced the effect in about 30% of the neurons. The effects appeared gradually during continuous administration of full-length PTH(1-84) or its active fragment, PTH(1-34), but not of an inactive fragment, PTH(39-84). However, the active fragment of the PTH-related peptide (PTHrP(1-34)) had little effect on [Ca2+]i during 60 min of administration. The PTH effect was inhibited by nifedipine, an L-type Ca2+ channel antagonist, and facilitated by S-(-)-BAY K 8644, an L-type Ca2+ channel agonist. Our findings suggest that PTH is one of the causal factors for the age-related increase in the density of voltage gated Ca2+ channels in hippocampal neurons.
Hirasawa
T
T
Graduate School of Human Life Science, Japan Women's University, Tokyo, Japan.
Nakamura
T
T
Morita
M
M
Ezawa
I
I
Miyakawa
H
H
Kudo
Y
Y
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002120:Calcium Channel Agonists / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects* / Q000378:metabolism; D020746:Calcium Channels, L-Type; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005333:Fetus; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D007150:Immunohistochemistry; D007424:Intracellular Fluid / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D010281:Parathyroid Hormone / Q000494:pharmacology*; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments / Q000494:pharmacology; D011506:Proteins / Q000494:pharmacology; D051381:Rats; D013997:Time Factors
D002120:Calcium Channel Agonists; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D005904:Glial Fibrillary Acidic Protein; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments; D011506:Proteins; C054296:parathyroid hormone-related protein (1-34); D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009543:Nifedipine; D002118:Calcium