Fig. 1

Histamine induces the efflux of NKCC1-accumulated Cl⁻, leading to intracellular Ca²⁺ rise in SCN neurons. (a, left panel) Traces from a Ca²⁺-imaging experiment which show the effect of bumetanide on histamine-elicited increase in [Ca²⁺]_i in an SCN neuron. (a, right panel) Graphs summarizing the effects of bumetanide on the histamine-elicited Ca²⁺ responses in 105 SCN neurons from 3 mice. The bar charts indicate the mean (± SEM) peak Ca²⁺ responses. b Traces from Cl⁻-imaging experiments show the effects of H1R agonist on [Cl⁻]_i in SCN cells. Up- and downward deflections of the trace denote decrease and increase in [Cl⁻]_i, respectively. c Traces and summary graphs showing the effects of bumetanide on H1R agonist-induced decrease (n = 81) and increase (n = 80) in [Cl⁻]_i in SCN cells. The bar charts indicate the mean (± SEM) peak Cl⁻ responses. The symbols connected by lines in (a) and (c) denote data from the same cells. **: p < 0.001, paired t-test