# Application of Modulators of Ca2+-Activated Big-Conductance Potassium Channels Against Cd2+-Induced Cytotoxicity: A Study on Two Rat Cell Lines, PC12 and AS-30D

## TL;DR

This study explores how modulators of potassium channels affect cell toxicity caused by cadmium in rat cell lines, focusing on mitochondrial function and reactive oxygen species.

## Contribution

The study reveals the role of BK(Ca) channels in modulating cadmium-induced cytotoxicity through mitochondrial and ROS pathways.

## Key findings

- BK(Ca) openers like NS004 and NS1619 increased ROS production and affected mitochondrial respiration in a time- and dose-dependent manner.
- Paxilline reduced apoptosis and ROS levels induced by BK(Ca) openers and cadmium in rat cells.
- The study shows that BK(Ca) channels are involved in modulating cadmium toxicity through mitochondrial and ROS pathways.

## Abstract

As we found earlier, paxilline (a Penicillium paxilli mycotoxin and blocker of Ca2+-activated big-conductance potassium channels, BK(Ca)s) attenuated Cd2+-induced cytotoxic effects, whereas BK(Ca) activators (NS004, NS1619) and Cd2+ were able to induce apoptosis, which was enhanced when used together. In this work, molecular mechanisms underlying the aforementioned effects were studied using two rat cell lines, PC12 and AS-30D, flow cytometry, and spectrofluorometric and polarographic techniques. Both NS004 and NS1619 were found to have time- and dose-dependent effects on cell viability, respiration, mitochondrial membrane potential, and intracellular reactive oxygen species (ROS) production. In PC12 cells, BK(Ca) openers exerted an uncoupling effect after 3 h, increasing the resting respiration, while they partially inhibited the maximal respiration after 5 and 24 h; in addition, after 3 h, a transient protection by NS004/NS1619 against Cd2+-induced decrease of cell viability was observed. In both cell types, NS004/NS1619 increased ROS production after 3 h and counteracted the mitigating effect of paxilline against Cd2+-induced necrosis. In turn, paxilline reduced NS004/NS1619-induced apoptosis in AS-30D cells and ROS increase produced by NS004/NS1619 and/or Cd2+ in PC12 cells. As a result, the involvement of the mitochondrial respiratory chain, ROS, and, very likely, BK(Ca)s, in the mechanisms of the modulatory effects of the BK(Ca) blocker/opener(s) used in the absence and presence of Cd2+ was revealed.