Figure 2

Adenosine-mediated enhancement of ciliary beat frequency is due to A _2B receptor activation. (A) Histogram showing that ciliary beat frequency enhancement was not eliminated by pre-incubation with a cocktail of CNT and ENT inhibitors (1 mM phloridzin, 100 μM dipyridamole, 10 μM NBMPR; n = 5). (B) Summary histogram showing that ciliary beat frequency did not increase in response to a no drug control (Cont., n = 10), nor selective concentrations of the A_2A agonist CGS 21680 (100 nM, n = 5), the A₁ agonist 2'MeCCPA (100 nM, n = 5), nor the A₃ agonist IB-MECA (100 nM, n = 5). There was no significant difference between the no drug control and CGS 21680, 2'MeCCPA, or IB-MECA. (C) Histogram demonstrating that the response to 1 μM NECA was significantly reduced by the A_2B antagonist MRS 1754 (100 nM, n = 9) and eliminated by the A_2B antagonist PSB 603 (1 μM, n = 10). Response to 300 μM BzATP was also reduced by MRS 1754 (100 nM, n = 8). (D) [Ca²⁺]_i was increased by 1 min focal application (↓) of 300 μM BzATP ([Black circle], n = 1 application/10 regions of interest), but not by 3 min applications of 1 μM NECA (○, n = 3 applications/30 regions of interest) or 30 μM adenosine, (□, n = 3 applications/30 regions of interest): note: ○ and □ symbols largely overlap. The percent change in fluorescence signal divided by baseline mean fluorescence intensity is shown in the Y-axis (%ΔF/F₀). *: P < 0.05 for all panels, data are means ± SEM. The n value indicates the number of slices tested.