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. 2009 Dec 23;103(2):1114–1122. doi: 10.1152/jn.00980.2009

Fig. 4.

Fig. 4.

p110γ- and p110β-specific inhibition of PI3K enhances the odorant response in rat ORNs. A: PI3Kγ inhibitor-1 (1 μM) significantly increased the rapid electrophysiological response of rat ORNs in situ. Representative recording from the dendritic knob of one ORN stimulated by H100 (0.5 s, 10−4 dilution). Inhibiting PI3K significantly increased the peak magnitude and the rate of rise, while decreasing the latency of the response, mimicking the effect of a pan-specific blockade (Fig. 2). The average spike frequency (SF) plotted as a histogram of the number of spikes in 1-s bins is shown under each trace. B and C: representative Ca2+ responses of 2 other dissociated rat ORNs to H100 (10−5 dilution) applied for 5 s at 100-s intervals (arrowheads). B: AS-252424 (424, 200 nM, black bar), another highly selective inhibitor of PI3Kγ, increased the Ca2+ response to H100. C: TGX-211 (TGX, 200 nM, black bar), a highly selective inhibitor of PI3Kβ, can also increase the Ca2+ response to H100. The ability of the cells to respond to 100 μM 3-isobutyl-1-methylxanthine (IBMX)/10 μM forskolin (IF) denotes them as canonical ORNs. The cells retain the ability to respond to a higher concentration of H100 (H-4, 10−4 dilution). The inhibitors alone did not induce a response. D and E: plots showing the normalized peak magnitude of the Ca2+ signal evoked by H100 before (solid symbols) and after (open symbols) inhibition of PI3K with the PI3Kγ inhibitor AS-252424 (200 nM) and the PI3Kβ inhibitor TGX-221 (200 nM). Responses were normalized to the response evoked by IBMX/forskolin. Solid lines represent the best fit of the pooled data with the Hill equation with the following parameters: (D) control kH = 0.98, concentration eliciting half-maximal response (EC50) = 10−5.01 dilution, AS-252424, kH = 1.3, EC50 = 10−5.56 dilution; (E) control kH = 1.4, EC50 = 10−4.55 dilution, TGX-221, kH = 1.6, EC50 = 10−5.16 dilution. F: representative Ca2+ response of another dissociated rat ORN to H100 (10−5 dilution) applied for 5 s at 100-s intervals (arrowheads) before and following blockade with AS-252424 (424, 200 nM) and TGX-221 (TGX, 200 nM). The cell retains the ability to respond to a higher concentration of H100 (H-4, 10−4 dilution) and to IBMX/forskolin (IF). Similar effect was found in a different 11 cells. Arrowheads indicate time of test odorant application.