Fig. 5. Metallothionein short interfering RNA (siRNA) reduces metallothioneins I and II (MT-I/II) mRNA levels in a dose-dependent manner and increases vulnerability to oxygen glucose deprivation. ( A ) Quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) was used to assess MT-I/II knockdown by a siRNA against MT-I/II (MTKD). A sham siRNA (ShamKD) construct was used as the control. ZnCl2was used to simulate MT-stimulating conditions. ( B ) Oxygen-glucose deprivation (OGD)–mediated toxicity was assessed by lactate dehydrogenase release assay (LDH) in mixed cortical cultures transfected with either ShamKD or the MTKD siRNA constructs. See Results for discussion of significance (n = 27). Insets indicate time course for experimental procedure. APC = isoflurane preconditioning.