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AT 1 Angiotensin Receptors Mobilize Intracellular Calcium in a Subclone of NG108–15 Neuroblastoma Cells
Author(s) -
Ransom J. T.,
Sharif N. A.,
Dunne J. F.,
Momiyama M.,
Melching G.
Publication year - 1992
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1992.tb10065.x
Subject(s) - angiotensin ii , medicine , endocrinology , dup , receptor , stimulation , chemistry , angiotensin receptor , losartan , antagonist , biology , biochemistry , gene duplication , gene
The effects of angiotensin II (AII) and related peptides on the mobilization of internal Ca 2+ were studied in a subclone of NG108–15 cells. The subclone, C1, was prepared by fluorescence‐activated cell cloning using a rapid response kinetics and a large response magnitude following stimulation by AII as the selection criteria. Angiotensin I, AII, and angiotensin III (AIII) stimulated Ca 2+ mobilization in the C1 cells in a concentration‐dependent manner (1 n M ‐100 μ M ), yielding EC 50 values of 437 ± 80 n M (n = 4; slope = 1.6 ± 0.3), 57 ± 8 n M (n = 12; slope = 1.5 ± 0.3), and 36 ± 5 n M (n = 7; slope = 1.4 ± 0.3), respectively. AIII was significantly more potent than AII ( p < 0.05). In contrast, Des‐Phe 8 ‐AII, AII‐hexapeptide (AII 3–8), and p ‐NH 2 ‐Phe 6 ‐AII (1–10 μ M ) were inactive as agonists. Although the effects of AII and AIII in C1 and parent NG108–15 cells were totally inhibited by the AT 1 receptor‐selective nonpeptide antagonist, DUP‐753 (0.3–1 μ M ), the AT 2 ‐selective antagonists, EXP‐655 and CGP42112A (1–10 μ M ), failed to block the effects of AII. DUP‐753 (0.3–100 n M ) produced dextral shifts of the AII‐induced concentration‐response curves and yielded an estimated affinity constant (pA 2 ) of 8.5 ± 0.2 (n = 16) using single‐point analysis involving different concentrations of DUP‐753. These data compared well with those obtained for the inhibition of AII‐induced aortic contractions by DUP‐753 (pA 2 = 8.5) reported previously by others. These data strongly support the identification of an AT 1 ‐angiotensin receptor subtype in the NG108–15. C1 subclone that is coupled to a Ca 2+ mobilization signal transduction mechanism.