Potency of RTX relative to capsaicin in selected assays in the rat
| Assay | Relative Potency |
|---|---|
| In vitro experiments | |
| Inhibition of [3H]RTX binding to DRG neurons (1) | 100,000 |
| Induction of 45Ca2+ uptake by DRG neurons (1) | 300 |
| Activation of single channels in patch-clamped DRG neurons (2) | 500 |
| Evoking currents via cloned VR1 expressed in oocytes (3) | 20 |
| Twitch inhibition in vas deferens (4) | 10,000 |
| Desensitization of urinary bladder to subsequent challange (4) | 1,000 |
| Induction of cGMP in DRG neurons (5) | 660 |
| Contractions of isolated urinary bladder (4) | 1 |
| In vivo experiments | |
| Inhibition of xylene-induced Evans’ blue extravasation (6) | 20,000 |
| Induction of hypothermia (6) | 7,000 |
| Pungency (eye-wipings) (6) | 10 |
| Activation of pulmonary chemoreflex (7, 8) | RTX inactive |
| Desensitization of pulmonary chemoreflex (7) | Capsaicin inactive |
References indicated in parentheses: (1) Ács et al., 1996b; (2) Oh et al., 1996; (3) Caterina et al., 1997; (4) Maggi et al., 1990; (5) Winter et al., 1990; (6) Szallasi and Blumberg, 1989a; (7)Szolcsányi et al., 1990; and (8) Szolcsányi et al., 1991.