Figure 3. Effect of hypoglycaemia on the [³H]CA released from rat carotid body evoked by moderate (7% O₂) hypoxia.

A, results obtained from two individual CBs. Control CB (continuous line) was incubated with solutions containing 5.5 mm glucose and equilibrated with 20% O₂ except between minutes 30 and 40 where the hypoxic stimulus (7% O₂-equilibrated solutions) was applied. Experimental CB was similarly treated, but the hypoxic incubating solution contained 1 mm glucose. Fractions collected every 10 min. B, mean evoked release (n = 10–11) elicited by 7% O₂ and by 7% O₂ with the reduction of glucose from 5.5 mm to 1 mm. Evoked release corresponds graphically to the area under the curves and the dashed–dotted line in Fig. 2A, which represents the interpolated basal release; mathematically it is calculated by the sum of dpm in samples 30–40 min, 40–50 min, 50–60 min and 60–70 min minus dpm in samples [(20–30 min + 70–80 min)/2]× 4. The resulting dpm is expressed as percentage tissue content. C, effect of low glucose (1 mm) on the mean (n = 11) time course of the release of [³H]CA evoked by 7% O₂ (stimuli, both 7% O₂ and 1 mm glucose, were applied during 10 min between minutes 12 and 22 of the experimental protocol; for the rest of the experiment the incubating solution contained 5.5 mm glucose). Each column represents the [³H]CA collected each 2 min. Data represent means +s.e.m.