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. 2013 Aug 27;170(2):415–425. doi: 10.1111/bph.12286

Figure 1.

Figure 1

Concentration–response relationships for the histamine evoked [Ca]i increase and inward current in PO/AH neurons and for the antagonism of these actions by trans-triprolidine and mepyramine. (A) [Ca]i responses to different concentrations of histamine from 3 PO/AH neurons. (B) concentration–response curve for the histamine-induced elevations of [Ca]i. Each point represents the average of data collected from 30 different PO/AH neurons. The data were fitted with a Hill function. The fit yielded an EC50 of 39 μM. (C) [Ca]i responses to histamine (100 μM) before during and after trans-triprolidine (1 μM) incubation. The trace represents the average of the responses from five cultured PO/AH neurons. Note that trans-triprolidine (1 μM) abolished the effects of histamine. (D) Concentration–response curve for the antagonist activity of trans-triprolidine and mepyramine on the [Ca]i responses to histamine (100 μM). Each point represents the average of data collected from 30 different PO/AH neurons. The datasets were fitted with logistic functions. The fits yielded an IC50 of 0.21 and 0.32 μM for trans-triprolidine and mepyramine respectively. (E) Inward current activated by several concentrations of histamine recorded in a cultured PO/AH neurons. The holding potential was −50 mV. (F) Concentration–response curve for the histamine activation of inward currents. Each point represents the average of data collected from nine different PO/AH neurons. The data were fitted with a Hill function. The fit yielded an EC50 of 36 μM. (G) Inward currents activated by histamine (20 μM) before (upper trace), during incubation with trans-triprolidine (1 μM), and after washout of the antagonist (lower trace). The neuron was held at −50 mV. The holding potential was −50 mV. (H) Concentration–response curve for the antagonist activity of trans triprolidine and mepyramine on the [Ca]i responses to histamine (100 μM). Each point represents the average of data collected from five different PO/AH neurons. The datasets were fitted with logistic functions. The fits yielded IC50 of 0.15 and 0.03 μM for trans-triprolidine and mepyramine respectively. (A–H) TTX (1 μM), CNQX (20 μM), AP-5 (50 μM) and bicuculline (20 μM) were present in the extracellular solution.