The Venom of Ornithoctonus huwena affect the electrophysiological stability of neonatal rat ventricular myocytes by inhibiting sodium, potassium and calcium current

Spider venoms are known to contain various toxins that are used as an effective means to capture their prey or to defend themselves against predators. An investigation of the properties of Ornithoctonus huwena (O.huwena) crude venom found that the venom can block neuromuscular transmission of isolated mouse phrenic nerve-diaphragm and sciatic nerve-sartorius preparations. However, little is known about its electrophysiological effects on cardiac myocytes. In this study, electrophysiological activities of ventricular myocytes were detected by 100 μg/mL venom of O.huwena, and whole cell patch-clamp technique was used to study the acute effects of the venom on action potential (AP), sodium current (I(Na)), potassium currents (I(Kr), I(Ks), I(to1) and I(K1)) and L-type calcium current (I(CaL)). The results indicated that the venom prolongs APD(90) in a frequency-dependent manner in isolated neonatal rat ventricular myocytes. 100 μg/mL venom inhibited 72.3 ± 3.6% I(Na) current, 58.3 ± 4.2% summit current and 54 ± 6.1% the end current of I(Kr), and 65 ± 3.3% I(CaL) current, yet, didn't have obvious effect on I(Ks), I(to1) and I(K1) currents. In conclusion, the O.huwena venom represented a multifaceted pharmacological profile. It contains abundant of cardiac channel antagonists and might be valuable tools for investigation of both channels and anti- arrhythmic therapy development.