Table 3 IB-MECA stimulated cAMP inhibition at WT A3R: activity of MRS 1220 and potential antagonists.

From: Pharmacological characterisation of novel adenosine A3 receptor antagonists

  

WT A3R Flp-In-CHO

pIC50a

Eminb

Basal c

True Basal d

Span e

n

Inverse agonism pEC50f.

IB-MECA only

 

10.72 ± 0.1

− 8.42 ± 2.6

107.7 ± 2.6

102.2 ± 2.9

116.1 ± 3.5

27

 

MRS 1220

0.1 nM

10.67 ± 0.1

9.8 ± 3.5**

107.6 ± 3.7

99.7 ± 4.0

97.9 ± 4.9*

9

 

1 nM

9.90 ± 0.1****

20.9 ± 3.8***

139.0 ± 3.1****

124.8 ± 4.1**

118.1 ± 4.8

8

9.21 ± 0.2

10 nM

8.39 ± 0.1****

46.7 ± 4.9****

143.6 ± 2.1****

133.8 ± 3.6****

96.9 ± 5.1*

8

 

K1

0.1 μM

10.55 ± 0.1

− 5.4 ± 4.5

117.2 ± 4.3

105.9 ± 4.3

122.5 ± 5.9

6

 

1 μM

10.23 ± 0.1***

7.9 ± 4.5*

141.3 ± 3.7****

132.0 ± 6.6****

133.3 ± 5.6

7

4.93 ± 0.1

10 μM

9.47 ± 0.1****

36.8 ± 4.4****

161.3 ± 2.9****

152.6 ± 5.4****

124.5 ± 5.1

6

 

K10

0.1 μM

10.69 ± 0.1

− 5.2 ± 4.3

125.3 ± 4.0**

125.1 ± 6.3*

130.5 ± 5.6

5

 

1 μM

10.13 ± 0.1****

− 1.3 ± 4.4

146.7 ± 3.5****

140.4 ± 4.2****

148.1 ± 5.5**

5

5.81 ± 0.1

10 μM

9.12 ± 0.1****

8.5 ± 6.4

161.1 ± 3.9****

150.0 ± 5.8****

152.6 ± 7.2****

5

 

K17

0.1 μM

10.75 ± 0.1

− 0.9 ± 3.2

115.5 ± 3,3

111.8 ± 4.5

116.5 ± 4.5

7

 

1 μM

10.17 ± 0.1****

6.5 ± 3.8

141.7 ± 3.2****

131.7 ± 5.2****

135.3 ± 4.8*

7

6.24 ± 0.2

10 μM

9.05 ± 0.1****

14.83 ± 5.2***

151.7 ± 3.0****

143.9 ± 6.1****

137.9 ± 5.8*

7

 

K18

0.1 μM

10.65 ± 0.1

5.4 ± 2.6

118.6 ± 2.6

118.5 ± 4.1

113.1 ± 3.5

6

 

1 μM

9.65 ± 0.1****

10.7 ± 4.1*

140.1 ± 2.6****

125.6 ± 5.1**

129.4 ± 4.7

6

6.84 ± 0.2

10 μM

8.38 ± 0.1****

28.0 ± 5.9****

147.7 ± 2.4****

138.6 ± 2.4****

119.7 ± 6.1

7

 

K25

0.1 μM

10.81 ± 0.1

7.1 ± 2.5

109.5 ± 2.5

108.9 ± 3.3

102.4 ± 3.4

6

 

1 μM

10.12 ± 0.1****

6.7 ± 3.8

126.7 ± 2.9**

124.0 ± 4.1*

120.1 ± 4.6

5

6.01 ± 0.1

10 μM

9.21 ± 0.1****

17.5 ± 3.2****

136.6 ± 1.8****

131.2 ± 4.1***

119.1 ± 3.5

6

 

K32

0.1 μM

10.74 ± 0.1

− 0.6 ± 4.8

127.6 ± 4.9**

116.5 ± 6.0

128.2 ± 6.6

5

 

1 μM

9.95 ± 0.1****

3.6 ± 4.3

146.9 ± 3.4****

130.5 ± 5.8***

143.3 ± 5.3**

5

6.79 ± 0.2

10 μM

9.09 ± 0.1****

17.7 ± 5.4***

152.3 ± 3.3****

140.2 ± 6.9****

134.6 ± 6.1

5

 
  1. Forskolin stimulated cAMP inhibition was measured in Flp-In-CHO stably expressing A3R following stimulation with 10 μM forskolin, compound at the indicated concentration and varying concentrations of IB-MECA.
  2. aNegative logarithm of IB-MECA concentration required to produce a half-maximal response in the absence (IB-MECA only) or presence of 0.1, 1 or 10 μM compound.
  3. bMinimum cAMP accumulation of IB-MECA as % of the 10 μM forskolin response relative to IB-MECA only; the lower plateau of the fitted sigmoidal dose response curve.
  4. cThe upper plateau of the fitted sigmoidal dose response curve corresponding to % of the 10 μM forskolin inhibition, relative to IB-MECA.
  5. dThe cAMP accumulation when stimulated with compound at the indicated concentration and 10 μM forskolin stimulation only.
  6. eThe difference between Emin and basal signaling.
  7. fValue reported to determine inverse agonism: negative logarithm of compound concentration required to produce a half-maximal response.
  8. Data are expressed as mean ± SEM obtained in n separate experiments. Inverse agonist experiments were conducted in 3 separate experiments. Statistical significance (*p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001) compared to ‘IB-MECA only’ was determined by one-way ANOVA with Dunnett’s post-test.
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