Figure 8.
NO production is key instretch-mediated vulner ability to NMDA toxicity. Cell death in A and B was measured at 20 hr. A, Effects of l-NAME, a NOS inhibitor, on cell death under the indicated conditions. Cultures were preincubated with 100 μm l-NAME for 30 min. The asterisk inicates the difference from paired control (t18 = 4.141; p < 0.001). NS, Not different from paired control (t25 = 1.14; p = 0.313). The bars represent the mean + SE of 6-19 cultures obtained from three separate dissections. B, Attenuation of SNP (300 μm; an NO donor) toxicity by the ROS scavenger MnTBAP. The solutions contained MK-801 (10 μm), CNQX (10 μm), and nimodipine (2 μm) to block Ca influx through these pathways. SNP was applied for 1.5 hr. Previous stretch enhanced the vulnerability of neurons to SNP (*t16 = 5.583; p < 0.001), and this was abolished with a 30 min pretreatment with 200 μm MnTBAP. The bars represent the mean + SE of 6-12 cultures obtained from three separate dissections. C, Effect of NMDA treatment on nitrotyrosine staining at the indicated time and conditions. D, Quantification of nitrotyrosine staining intensity at the indicated times. Background-subtracted fluorescence intensity measurements were taken from 5-15 randomly chosen fields from each culture using identical excitation wavelengths, microscope, and camera settings. The bars indicate the mean + SE of two cultures from each of two separate experiments. The asterisks indicate the difference from unstretched controls at the same time point (Bonferroni t test; p < 0.05).