Cell experiment:

To assay intracellular ROS, HCT116 cells are preincubated with 20 μM dichlorofluorescein diacetate (DCF DA) for 15 min at 37℃ and then treated with Capsazepine. After 1 h of incubation, the increase in fluorescence resulting from the oxidation of DCF DA to DCF is measured by flow cytometry. The mean fluorescence intensity at 530 nm is calculated for at least 10,000 cells at a flow rate of 250-300 cells/s.

Animal experiment:

To verify the role of TRPV1 on lung mechanics during LPS-induced ALI, the animals (n = 10 per group) are pre-treated with vehicle or Capsazepine (15 mg/kg; s.c.), then receive saline or LPS (5 mg/kg, i.p.) after 10 min. Thus, the mice are randomly divided into four groups with 10 mice in each group: (i) control (vehicle + saline), (ii) Capsazepine + saline, (iii) vehicle + LPS and (iv) Capsazepine + LPS. After a 24-hr treatment with saline or LPS, the mice are anaesthetized and paralysed and lung mechanics function is evaluated. Afterwards, the lungs are removed for histology.

• Cell Reports 39.1 (2022): 110625. PMID:35385753

Capsazepine is a competitive antagonist of vanilloid (capsaicin) receptor with IC50 value of 562 nM.[1]

Capsazepine is a synthetic analogue of capsaicin, which activates the TRPV1 ion channel, thereby, blocks the painful sensation of heat caused by capsaicin. Capsazepine blocked voltage-activated calcium currents in adult rat dorsal root ganglion neurons with EC50 value of 7.7±1.4 μM.[2] Capsazepine was also able to block the response of TRPM8 to menthol (IC50=18±1.1 μM).[3] Capsazepine also inhibited nicotinic acetylcholine receptors in rat trigeminal ganglia at 10μM.[4] In human colon cancer cells, capsazepine treatment activated caspase -8, –9, and -3, induced death receptors (DRs) DR5 and DR4, then sensitized the cells to TRAIL-induced apoptosis.[5] Capsazepine is thought to be a tool to study the TRPV1 ion channel.

References:
1. C. S. Walpole, S. Bevan, G. Bovermann, J. J. Boelsterli, R. Breckenridge, J. W. Davies, G. A. Hughes, I. James, L. Oberer, J. Winter and et al., J Med Chem 1994, 37, 1942-1954.
2. R. J. Docherty, J. C. Yeats and A. S. Piper, Br J Pharmacol 1997, 121, 1461-1467.
3. H. J. Behrendt, T. Germann, C. Gillen, H. Hatt and R. Jostock, Br J Pharmacol 2004, 141, 737-745.
4. L. Liu and S. A. Simon, Neurosci Lett 1997, 228, 29-32.
5. B. Sung, S. Prasad, J. Ravindran, V. R. Yadav and B. B. Aggarwal, Free Radic Biol Med 2012, 53, 1977-1987.