Substance P-evoked calcium mobilization and ionic current activation in the human astrocytoma cell line U 373 MG: pharmacological characterization.
In the human astrocytoma cell line U 373 MG, application of substance P (SP) leads to a transient increase in cytosolic calcium concentration and to a biphasic current response in voltage-clamped cells. Using these two functional assays we have characterized pharmacologically the SP response in U 373 MG cells. SP and [L-Pro9]SP displayed high potencies in both assays with EC50 values of 2.5 x 10(-9) M and 1 x 10(-9) M on calcium responses and 1 x 10(-9) M and 5 x 10(-9) M on ion current responses, respectively. The high potency of SP and [L-Pro9]SP as well as the low potency of [Lys5,MeLeu9,N-Leu10]neurokinin A(4-10) and the inactivity of senktide demonstrate the NK1-type pharmacology of these responses. Furthermore, the NK1 antagonists (+/-)-CP 96,345, its chloro analogue, (+/-)-cis-3-(2-chlorobenzylamino)-2-benzhydrylquinuclidine, and RP 67580 were potent antagonists of both SP responses. For the calcium mobilization induced by SP (10(-7) M), the IC50 values for the three antagonists were 4 x 10(-10) M, 4 x 10(-9) M, and 9 x 10(-9) M, respectively, whereas on the current response evoked by SP (10(-8) M), the IC50 values were 8 x 10(-9) M, 2.4 x 10(-8) M, and 1.2 x 10(-7) M, respectively. Despite differences in the absolute IC50 values obtained with both techniques, the relative potencies of the three antagonists correlate fairly well.(ABSTRACT TRUNCATED AT 250 WORDS)
Pradier
L
L
Rhone-Poulenc Rorer Biology Department, Centre de Recherche de Vitry-Alfortville, Vitry sur Seine, France.
Heuillet
E
E
Hubert
J P
JP
Laville
M
M
Le Guern
S
S
Doble
A
A
D001254:Astrocytoma; D001713:Biphenyl Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D005456:Fluorescent Dyes; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D054833:Isoindoles; D008564:Membrane Potentials / Q000187:drug effects; D011812:Quinuclidines / Q000494:pharmacology; D018040:Receptors, Neurokinin-1 / Q000187:drug effects / Q000502:physiology; D018039:Receptors, Tachykinin / Q000187:drug effects / Q000502:physiology*; D013050:Spectrometry, Fluorescence; D013373:Substance P / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D001713:Biphenyl Compounds; D005456:Fluorescent Dyes; D007211:Indoles; D007473:Ion Channels; D054833:Isoindoles; D011812:Quinuclidines; D018040:Receptors, Neurokinin-1; D018039:Receptors, Tachykinin; C071099:3-(2-chlorobenzylamino)-2-benzhydrylquinuclidine; C071693:7,7-diphenyl-2-(1-imino-2-(2-methoxyphenyl)ethyl)perhydroisoindol-4-one; D013373:Substance P; C048960:indo-1; D002118:Calcium; C066892:CP 96345