Figure 7.

Purinergic receptor antagonists potentiate odor-evoked calcium transients. A, B, Representative normalized calcium transients in response to odor in the absence (A) or presence (B) of P2 receptor antagonists (100 μm suramin + 25 μm PPADS) from individual mouse ORNs in fluo-4-AM-loaded OE slices. Filled triangles correspond to the time of loop injection of the odors. Slices were pretreated for 3 min with Ringer's solution or P2 receptor antagonists (open columns). C, Average peak calcium transient amplitudes are shown (means + SEM), as are the predicted peak amplitudes (filled circles) for the second application (n = 30 ORNs from seven slices for control and n = 22 ORNs from 12 slices for P2 receptor antagonists). The asterisk indicates a significant increase in [Ca²⁺]_i in the observed compared with predicted (p = 0.024, paired Student's t test). D, Representative traces depicting basal fluorescence levels when bath is switched at 10 sec (open column) from Ringer's solution to either P2 receptor antagonists (solid lines) or Ringer's solution (dotted lines). The fluorometric signals shown are expressed as relative fluorescence change, ΔF/F = (F - F₀)/F, where F₀ is calculated from the linear rate of decay during the first 15 sec of the recording (F₀ = mX + b). Thus, values of 0 represent no change in fluorescence and calcium levels, negative values represent decreases in calcium, and positive values represent increases in basal calcium levels.