Alopecosa nagpag acts on cardiac ventricular myocytes to kill prey

Spiders are excellent predator to kill their prey by peptide toxins from its venoms. Alopecosa nagpag ( A. nagpag ) is a new identified wolf spider distributing in Yunnan province and nothing has known about the venom. In this study, venom of A. nagpag showed mild toxicity to Kunming mouse with LD ₅₀ of 3.32 mg/kg. Action potential duration (APD) was prolonged in a frequency-dependent manner and whole currents of neonatal rat ventricular myocytes (NRVMs) were inhibited by venom. Meanwhile, venom of A. nagpag could largely increase L calcium currents (I _CaL ). Whereas sodium current (I _Na ) and rapidly activating delayed rectifier potassium current (I _Kr ) were significantly decreased by 100 μg/mL venoms. No obvious inhibition was found on other ion channels such as rapidly activating and inactivating transient inward (I _K1 ), rapid (I _Kr ) and slow (I _Ks ). As those ion channels play critical role in rhythm of cardiac ventricular myocytes, A. nagpag may lead prey to death by changing cardiac rhythm.