[Arg8]-vasopressin-induced increase in intracellular Ca2+ concentration in cultured rat hippocampal neurons.
Changes in intracellular Ca2+ concentration ([Ca2+]i) induced by [Arg8]-vasopressin (AVP) were studied in cultured rat hippocampal neurons by fura-2 fluorometry. AVP (10-1,000 nM) caused a dose-dependent increase in [Ca2+]i. The selective V1 vasopressin receptor agonist [Phe2, Ile3, Orn8]-vasopressin also induced a significant increase in [Ca2+]i, whereas the selective V2 vasopressin receptor agonist [deamino Cys1, D-Arg8]-vasopressin showed no effect. The AVP-induced increase in [Ca2+]i was inhibited by the selective V1 vasopressin receptor antagonist d(CH2)5[Tyr2(Me), Arg8]-vasopressin and nonpeptide V1 antagonist OPC-21268. On the other hand, no antagonistic effects were observed with the V2 vasopressin antagonist desglycinamide-[d(CH2)5, D-Ile2, Ile4, Arg8]-vasopressin and nonpeptide V2 antagonist OPC-31260. The increase in [Ca2+]i induced by AVP was abolished after removal of extracellular Ca2+. In addition, AVP-induced [Ca2+]i elevation was not affected by treatment with verapamil, which blocked the [Ca2+]i increase induced by an isotonic high K(+)-medium (50 mM). However, omega-conotoxin GVIA completely inhibited the effect of AVP. These results suggested that the AVP-induced [Ca2+]i increase in cultured rat hippocampal neurons is due to influx of Ca2+ through V1 VP receptors coupled with N-type calcium channels.
Mihara
T
T
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Okayama University, Japan.
Tarumi
T
T
Sugimoto
Y
Y
Chen
Z
Z
Kamei
C
C
D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects; D020746:Calcium Channels, L-Type; D002478:Cells, Cultured; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009994:Osmolar Concentration; D051381:Rats / Q000196:embryology; D017483:Receptors, Vasopressin / Q000819:agonists
D065092:Antidiuretic Hormone Receptor Antagonists; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D002118:Calcium