Allosteric interactions between receptor site 3 and 4 of voltage-gated sodium channels: a novel perspective for the underlying mechanism of scorpion sting-induced pain.

Abstract

BACKGROUND:

BmK I, a site-3-specific modulator of voltage-gated sodium channels (VGSCs), causes pain and hyperalgesia in rats, while BmK IT2, a site-4-specific modulator of VGSCs, suppresses pain-related responses. A stronger pain-related effect has been previously attributed to Buthus martensi Karsch (BmK) venom, which points out the joint pharmacological effect in the crude venom.

METHODS:

In order to detect the joint effect of BmK I and BmK IT2 on ND7-23 cells, the membrane current was measured by whole cell recording. BmK I and BmK IT2 were applied successively and jointly, and the synergistic modulations of VGSCs on ND7-23 cells were detected.

RESULTS:

Larger peak INa and more negative half-activation voltage were elicited by joint application of BmK I and BmK IT2 than by application of BmK I or BmK IT2 alone. Compared to the control, co-applied BmK I and BmK IT2 also significantly prolonged the time constant of inactivation.

CONCLUSIONS:

Our results indicated that site-4 toxin (BmK IT2) could enhance the pharmacological effect induced by site-3 toxin (BmK I), suggesting a stronger effect elicited by both toxins that alone usually exhibit opposite pharmacological effects, which is related to the allosteric interaction between receptor site 3 and site 4. Meanwhile, these results may bring a novel perspective for exploring the underlying mechanisms of scorpion sting-induced pain.

• Authors: Yi-Jun Feng, Qi Feng, Jie Tao, Rong Zhao, Yong-Hua Ji
• Journal: The journal of venomous animals and toxins including tropical diseases (J Venom Anim Toxins Incl Trop Dis) Vol. 21 Pg. 42 ( 2015) ISSN: 1678-9199 [Print] Brazil
• PMID: 26491429 (Publication Type: Journal Article)