Electrophysiological response elicited by Pelagia noctiluca crude venom in human cells

Pelagia noctiluca is one of the most dangerous jellyfish in the Mediterranean Sea and is abundant in the Strait of Messina. P. noctiluca crude venom can impair the regulatory volume decrease (RVD) after hypotonic stress and lead to cell swelling in isotonic conditions. In this study, we characterized the electrical responses elicited in Human Embryonic Kidney (HEK 293) cells by the crude venom of the jellyfish, with the aim of verifying a possible inhibition of ion channels involved in RVD. The species were collected in the Strait of Messina and crude venom extracted to evaluate the effects on cell membrane conductance by the patch clamp technique in whole-cell configuration. Surprisingly, P. noctiluca crude venom (0.025 μg/μl) failed to block potassium and swelling-activated chloride (IClswell) currents, but elicited two different electrophysiological responses in HEK 293 cells. First, a predominant inward sodium current, amiloride-sensitive, probably leading to an influx of water and dramatic cell swelling in isotonic condition, RVD impairment and significant activation of IClswell in hypotonic conditions. Second, a smaller chloride current, DIDS and NPPB insensitive, unlikely due to the activation of endogenous channels. A comparative study performed in HeLa and NIH/3T3 cells led to similar findings. These results added new information on the mechanisms of action of P. noctiluca crude venom and open the way to possible pharmacological applications of its active components.