Acetyl L‐Carnitine Protects Zebrafish Embryos From Verapamil and Inorganic Arsenic‐Induced Cardiotoxicity and Developmental Toxicity With No Effect on Supernumerary Motor Neuron Development

Verapamil (a P-glycoprotein inhibitor) and inorganic arsenic cotreatment has been shown to be toxic in chick cardiomyocytes. Previously, we have shown that sodium arsenite at 200 mg/L did not cause developmental toxicity or cardiotoxicity in zebrafish embryos. Here, we investigated the effect of verapamil and sodium arsenite cotreatment on the zebrafish embryos. Embryos at 5 h post-fertilization (hpf) were exposed to sodium arsenite (100-400 mg/L; 0.77-3.08 mM) in the presence or absence of 20 μM verapamil for 67 h. At 72 hpf, all the embryos treated with sodium arsenite or verapamil alone were alive, while only ~23% and ~17% survived in the groups cotreated with 20 μM verapamil and 100 mg/L or 200 mg/L arsenite, respectively. However, 10 μM of verapamil and 200 mg/L sodium arsenite cotreatment resulted in 100% embryo survival. Inductively coupled plasma mass spectrometry analysis showed that in the verapamil and sodium arsenite cotreated group, the internal arsenic concentration was significantly higher than in the group treated with only sodium arsenite, suggesting that verapamil inhibited arsenic efflux. Surprisingly, verapamil, a calcium channel blocker, reduced sodium arsenite-induced apoptosis but caused developmental toxicity and cardiotoxicity in the sodium arsenite cotreated embryos, without affecting arsenite-induced supernumerary motor neuron development. Furthermore, acetyl L-carnitine (ALCAR) completely abolished both developmental toxicity and cardiotoxicity induced by sodium arsenite and verapamil cotreatment. We show for the first time that ALCAR prevents toxicities induced by arsenic and verapamil cotreatment in zebrafish embryos, a vertebrate model for investigating chemical toxicity.