Figure 7.
Activation of GABAA receptors at the time of the AD potentiates cell swelling. A, Schematic diagram of light transmittance measurement. Intracellular organelles scatter light and reduce the transmitted light. When cells swell, the organelles are diluted, reducing scattering and increasing transmittance. B, Light levels transmitted through a slice remained constant until the time of the AD, when there was a sudden increase in transmittance attributed to cellular swelling. The bottom trace shows the extracellularly recorded field potential for correlation of the timing of swelling and of the AD. C, With GABAA receptors blocked, the initial increase in light transmittance (marked by a horizontal arrow) at the time of the AD was reduced, but transmittance continued to increase slowly over a number of minutes. D, The initial light increase at the time of the AD was reduced in GABAzine (8 slices control ischemia solution, 8 interleaved slices with GABAzine). E, The final increase in light transmittance, measured 5 min after the AD, was unchanged in the presence of GABAzine. F, The initial light increase at the time of the AD was reduced by pretreating slices with 0.5 μm concanamycin and applying 100 μm SKF-89976A throughout (14 slices control ischemia, 15 interleaved slices with concanamycin plus SKF-89976A). G, The final increase in light transmittance, measured 5 min after the AD, was unchanged by treatment with concanamycin and SKF-89976A.