Abstract
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 (INa), potassium currents (IKr, IKs, Ito1 and IK1) and L-type calcium current (ICaL). The results indicated that the venom prolongs APD90 in a frequency-dependent manner in isolated neonatal rat ventricular myocytes. 100 μg/mL venom inhibited 72.3 ± 3.6% INa current, 58.3 ± 4.2% summit current and 54 ± 6.1% the end current of IKr, and 65 ± 3.3% ICaL current, yet, didn't have obvious effect on IKs, Ito1 and IK1 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.