Table 2

Effect of various amphipathic compounds on [³H]5-HT binding, cAMP production, and GTPγ³⁵S Binding at human 5-HT_7Areceptors expressed in HEK293 cells

	[³H]5-HT Binding		cAMP Production		GTPγ³⁵S Binding of 5-HT
	K_D	B_max	EC₅₀	E_max	GTPγ³⁵S Binding of 5-HT
	nM	pmol/mg protein	nM	pmol/well	%
Control	1.5 ± 0.1	1.7 ± 0.2	8.1 ± 0.7	9.1 ± 0.1	100
CHAPS^2-a	1.4 ± 0.1	2.6 ± 0.1^2-150	3.7 ± 0.4^2-160	8.4 ± 0.3	133 ± 7
Oleic acid, 15 μM	1.3 ± 0.2	2.2 ± 0.2^2-150	4.0 ± 0.4^2-160	9.0 ± 0.5	137 ± 5
FF-BSA, 3%	1.2 ± 0.2	1.1 ± 0.1^2-150	13.9 ± 1.2^2-160	9.1 ± 0.8	56 ± 4
LPC (50 μM)	1.4 ± 0.1	1.2 ± 0.2^2-150	15.8 ± 1.6^2-160	8.3 ± 0.3	55 ± 10

Cellular cAMP changes were monitored using a FlashPlate assay kit from PerkinElmer in HEK 293 cells in a 96-well plate. A standard curve with various concentrations of cAMP was constructed, following the vendor's protocol. The basal levels of cAMP were less than 0.2 pmol/well and were not appreciably affected by addition of the listed compounds. The 5-HT–induced GTPγ³⁵S binding was measured in isolated HEK 293 cell membranes in the presence or absence of 10 μM 5-HT and 2 nM GTPγ³⁵S. Methiothepin at 100 μM blocked 5-HT–induced GTPγ³⁵S binding and by itself showed no effect. The data represent the mean ± S.E.M. (n = 3).

↵2-a 0.2% for [³H]5-HT Binding, but 0.1% for cAMP and GTPγ³⁵S binding.
↵2-150 , p < 0.01 from t test
↵2-160 , p < 0.05 from t test