Transformation of simple and complex intracellular Ca²⁺-oscillations into high-amplitude impulse-shaped Ca²⁺-oscillations by NH₄Cl or bicuculline.

<p>Neuronal cultures 12 DIV. Resting calcium level is outlined by dot-dashed lines. Calcium increment over resting level (VCi = ΔCa (a.u.)/min) is indicated on the Figures as VCi. All other abbreviations as on <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134145#pone.0134145.g001" target="_blank">Fig 1</a>. Total number of neuronal cells in networks are: N = 116, 132, 98, 110 for Fig A, B, C and D, correspondingly. <b>(A</b>–<b>C)</b> NH₄Cl induces high-amplitude Ca²⁺-oscillations in representative cells. 200 nM of L-glutamate was added before application of NH₄Cl. <b>(C)</b> The experiment was performed in the presence of 10 μM L-NAME and 200 nM of L-glutamate. <b>(D)</b> 10 μM of bicuculline evokes high-amplitude Ca²⁺-oscillations in spontaneously firing cell. Only parts of total records are presented on Fig B and C. Initial parts were omitted for simplicity.