Trifluoperazine inhibits phosphoinositide hydrolysis as a histamine H1-receptor antagonist.
In human astrocytoma cells (1321N1), trifluoperazine potently inhibited histamine-induced phosphoinositide hydrolysis, while it slightly inhibited carbachol-induced phosphoinositide hydrolysis. Trifluoperazine as well as diphenhydramine inhibited [3H]mepyramine binding in astrocytoma cell membranes with Ki values of 0.052 microM and 0.005 microM, respectively. However, trifluoperazine only slightly inhibited [3H]quinuclidinyl benzilate binding with a Ki value of 3 microM. These results indicate that trifluoperazine specifically inhibits histamine-induced phosphoinositide hydrolysis as a histamine H1-receptor antagonist in human astrocytoma cells.
Department of Pharmacology, Fukushima Medical College, Japan.
N
N
Nakahata
H
H
Ishimoto
A
A
Takahashi
K
K
Ohmori
M
M
Kurita
D001254:Astrocytoma / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology; D004789:Enzyme Activation; D006632:Histamine / Q000494:pharmacology; D006634:Histamine H1 Antagonists / Q000494:pharmacology*; D006801:Humans; D006868:Hydrolysis / Q000187:drug effects; D007700:Kinetics; D010716:Phosphatidylinositols / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology; D014268:Trifluoperazine / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000187:drug effects / Q000378:metabolism
D006634:Histamine H1 Antagonists; D010716:Phosphatidylinositols; D011976:Receptors, Muscarinic; D014268:Trifluoperazine; D006632:Histamine; D002217:Carbachol; D010738:Type C Phospholipases