Precision local anaesthesia

Precision local anaesthesia — a pain-selective differential block

The first half is an entry port — TRPV1 or TRPA1 — expressed on C-fibre nociceptors but absent from large touch afferents and motor efferents. The second is a permanently charged firing-threshold raiser that cannot cross resting membranes and can therefore reach its site only by passing through that open port. Opening the port admits the raiser into nociceptors alone, so the resulting block is differential: pain fibres are silenced while motor and light-touch fibres are largely spared. The mechanism shape (selective entry → selective block) is graded [F], anchored to Binshtok, Bean and Woolf (Nature 2007), in which a charged sodium-channel blocker entering through TRPV1 produced a nociceptive-selective block that was attenuated in TRPV1-knockouts. The cited tool compounds (QX-314, chloroprocaine) are named only as experimental anchors, never as proposed therapeutics. The differential-block ratio, duration, concentration, and every clinical magnitude remain [O] OPEN and are not asserted here.

Falsifier. If opening the nociceptor-selective port does not produce a differential block — if motor and touch are blocked as much as pain — the entry-port-selectivity premise is wrong for that port or tissue, and this direction is killed.