Figure 6. Secretory response of glomus cells to hypoxia in human carotid body slices.

A, top: amperometric signal showing catecholamine release from a glomus cell exposed to low (∼10 mmHg) and 40 mm K⁺. Each spike represents a single exocytotic event. Bottom: cumulative secretion signal (in picocoulombs, pC), resulting from the time integral of the amperometric recording. Slice from the CB of a 27-year-old subject. B, frequency–charge distribution of individual exocytotic events. Mean vesicle quantal size was 72.2 ± 24.9 fC (n= 1058 spikes; 6 recordings; 4 donors aged from 27 to 62 years). C and D, average secretion rate measured under basal conditions and in response to high K⁺ and hypoxia (basal: 120 ± 36 fC min⁻¹; 40 mm KCl: 6821 ± 2290 fC min⁻¹; hypoxia: 1910 ± 521 fC min⁻¹; n = 13 recordings, 8 donors, aged from 27 to 62 years). Secretion rate is expressed in pC min⁻¹ (mean ± SEM).