Table 1

Parameters of concentration-response curves with the vanilloid receptor agonists capsaicin and RTX under control conditions and in the presence of the antagonists capsazepine (CZP), L-R4W2, and D-R4W2

AgonistAntagonistnMaximumplog EC50pHill Slopep
Capsaicin110.466 ± 0.091−6.60 ± 0.101.97 ± 0.21
CZP (3 μM)190.463 ± 0.056N.S.−6.44 ± 0.05N.S.2.16 ± 0.18N.S.
CZP (10 μM)120.429 ± 0.077N.S.−5.71 ± 0.08 1-150 1.59 ± 0.23N.S.
CZP (30 μM)170.573 ± 0.042N.S.−5.53 ± 0.05 1-150 2.16 ± 0.27N.S.
CZP (100 μM)110.429 ± 0.053N.S.−5.04 ± 0.21 1-150 1.50 ± 0.16N.S.
l-R4W2 (0.1 μM)140.523 ± 0.082N.S.−5.72 ± 0.09 1-150 1.72 ± 0.12N.S.
l-R4W2 (1 μM)140.527 ± 0.069N.S.−5.43 ± 0.07 1-150 1.54 ± 0.16N.S.
l-R4W2 (10 μM)110.470 ± 0.067N.S.−4.96 ± 0.15 1-150 1.86 ± 0.32N.S.
d-R4W2 (0.1 μM)140.489 ± 0.081N.S.−6.66 ± 0.07N.S.1.48 ± 0.11N.S.
d-R4W2 (1 μM)100.572 ± 0.098N.S.−5.73 ± 0.14 1-150 1.82 ± 0.19N.S.
d-R4W2 (10 μM)120.675 ± 0.100N.S.−5.23 ± 0.16 1-150 1.40 ± 0.15N.S.
RTX100.481 ± 0.115−10.04 ± 0.051.32 ± 0.23
CZP (10 μM)70.517 ± 0.121−9.64 ± 0.201.79 ± 0.27
l-R4W2(0.1 μM)60.420 ± 0.089N.S.−9.40 ± 0.06 1-150 1.99 ± 0.17N.S.
l-R4W2 (1 μM)70.519 ± 0.081N.S.−9.09 ± 0.25 1-150 1.87 ± 0.41N.S.
l-R4W2 (10 μM)130.446 ± 0.031N.S.−8.74 ± 0.13 1-150 1.68 ± 0.25N.S.
d-R4W2 (0.1 μM)120.469 ± 0.069N.S.−10.21 ± 0.14N.S.1.75 ± 0.31N.S.
d-R4W2 (1 μM)120.564 ± 0.081N.S.−9.55 ± 0.15 1-150 1.09 ± 0.14N.S.
d-R4W2 (10 μM)100.389 ± 0.053N.S.−9.68 ± 0.06N.S.2.77 ± 0.43 1-150

Values are mean ± S.E.M. of n experiments; maximum is expressed as increase in Fura-2 fluorescence ratio (340 nm/380 nm) above baseline ratio. Statistical differences were analyzed by ANOVA, followed by Dunnett's multiple comparisons test versus control, with control being either capsaicin without antagonist or RTX without antagonist.

  • 1-150  p < 0.05, statistically significant difference.