Table 1.

Stimulus/Agent	Mechanism	Response	Ref
Capsaicin	Intracellular N & C terminal	Activation, Increased Ca⁺⁺ _I Desensitization Cell death	^{19, 25,26}
Resiniferatoxin (RTX)	Transmembrane domain	Slow irreversible activation, Increased Ca⁺⁺_I Depolarizing block Cell death	^27–31
Heat	Multiple sites – C-terminal; PIP2	Activation at Temp >43 °C Increased Ca⁺⁺_i	^{19, 32–34}
Acid/Base	Extracellular (H+) Intracellular (−OH)	Activation & sensitization	^{19,32, 35,36}
Anandamide	Direct intracellular binding	Vasodilation, Activation, Sensitization	^37–40
Bradykinin (BK)	12-HPETE Leukotriene B₄; PKC	Activation & Sensitization	^41–43
ATP	P2Y2/PKC	Sensitization & Activation	^44–46
Nerve Growth Factor (NGF)	TrkA/PI3K	Activation & Sensitization Increased expression	^{47, 48}
Trypsins	PAR2/PKC	Sensitization	^{49, 50}