Final answer:
Incorrect preparation or concentration of rotenone can influence its capacity to kill SH-SY5Y cells by inadequately inhibiting the electron transport chain and generating lower levels of reactive oxygen species. Ensuring proper dilution, stability, and handling of rotenone, along with using appropriate controls, is essential for valid cytotoxicity results.
Step-by-step explanation:
The preparation or concentration of rotenone solution can indeed affect its efficacy in inducing cytotoxicity in SH-SY5Y cells. Rotenone is a known inhibitor of the mitochondrial electron transport chain, specifically targeting Complex I. It impedes the transfer of electrons from Complex I to ubiquinone, which is crucial for ATP production in cellular respiration. As a result of this inhibition, cells are unable to generate energy efficiently and reactive oxygen species (ROS) are produced as a byproduct, which can cause oxidative damage leading to cell death.
Issues with the preparation of rotenone, such as incorrect dilution or instability of the solution, could result in a lower concentration than needed for effective cytotoxicity. Similarly, improper storage or handling might affect the potency of the compound. In cell culture experiments, ensuring accurate concentrations and viable reagents is vital for consistent results, as seen in experiments with HepG2 and HT-29 cells where specific concentrations of test compounds resulted in significant growth inhibition.
Moreover, one must consider the potential of dimethyl sulfoxide (DMSO), used as a solvent, to affect cell viability at higher concentrations. However, the study mentions that the highest DMSO concentration (0.1%) did not affect cell proliferation or cytotoxicity, thereby excluding it as a significant variable in the efficacy of rotenone against these cells. As a control measure, it is important to verify the activity and proper function of rotenone as an electron transport chain inhibitor, which can be done through parallel assays or using a chemical like methylene blue as an antidote, highlighting the specificity of its action on the cellular respiration pathway.