Use of bulleyaconitine A as an adjuvant for prolonged cutaneous analgesia in the rat.
BACKGROUND
Bulleyaconitine A (BLA) is an analgesic and antiinflammatory drug isolated from Aconitum plants. BLA has several potential targets, including voltage-gated Na+ channels. We tested whether BLA elicited long-lasting cutaneous analgesia, when co-injected with lidocaine and epinephrine, as a model for prolonged infiltration anesthesia.


METHODS
The local anesthetic properties of BLA were assessed by the patch-clamp technique in HEK293t cells expressing Nav1.7 and Nav1.8 neuronal Na+ channels, both crucial for nociception. Drug solutions (0.6 mL) were injected subcutaneously via rat shaved dorsal skin. Inhibition of the cutaneous trunci muscle reflex was evaluated by pinpricks. Skin cross-sections were stained with hematoxylin and eosin or with antibodies against PGP9.5.


RESULTS
BLA at 10 microM interacted minimally with resting or inactivated Nav1.7 and Nav1.8 Na+ channels when infrequently stimulated to +50 mV for 3 ms. However, when stimulated at 2 Hz for 1000 pulses, their peak Na+ currents were >90% reduced by BLA. This use-dependent inhibition was not significantly reversed after 15-min washing. Complete nociceptive blockade after injection of lidocaine (0.5%)/epinephrine (1:200,000) lasted for approximately 1 h in rats; full recovery occurred after approximately 6 h. Co-injection of 0.125 mM BLA with lidocaine/epinephrine increased the duration of complete nociceptive blockade to 24 h. Full recovery occurred after approximately 6 days. Skin histology including peripheral nerve fibers appeared unaffected by BLA.


CONCLUSIONS
BLA inhibits Nav1.7 and Nav1.8 Na+ currents in a use-dependent manner. Co-injection of BLA at <or=0.125 mM with lidocaine and epinephrine elicits complete cutaneous analgesia that lasts for up to 24 h without adverse effects.
Wang
Chi-Fei
CF
Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St., Boston, MA 02115, USA.
Gerner
Peter
P
Schmidt
Birgitta
B
Xu
Zhen Zhong
ZZ
Nau
Carla
C
Wang
Sho-Ya
SY
Ji
Ru-Rong
RR
Wang
Ging Kuo
GK
D000157:Aconitine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000633:toxicity; D000759:Adjuvants, Anesthesia / Q000008:administration & dosage* / Q000494:pharmacology / Q000633:toxicity; D000698:Analgesia; D019162:Anesthetics, Combined; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000494:pharmacology / Q000633:toxicity; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000008:administration & dosage; D022781:Hepatocytes; D006801:Humans; D007279:Injections, Subcutaneous; D008012:Lidocaine / Q000008:administration & dosage; D062556:NAV1.7 Voltage-Gated Sodium Channel; D062559:NAV1.8 Voltage-Gated Sodium Channel; D018408:Patch-Clamp Techniques; D051381:Rats; D012867:Skin / Q000294:innervation* / Q000473:pathology; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000494:pharmacology
D000759:Adjuvants, Anesthesia; D019162:Anesthetics, Combined; D000779:Anesthetics, Local; D062556:NAV1.7 Voltage-Gated Sodium Channel; D062559:NAV1.8 Voltage-Gated Sodium Channel; C568317:SCN10A protein, human; C486866:SCN9A protein, human; C568319:Scn10a protein, rat; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D014662:Vasoconstrictor Agents; C052509:bulleyaconitine A; D008012:Lidocaine; D000157:Aconitine; D004837:Epinephrine