Table 1. Ca2+ dependence of the rate of exocytosis in various secretory cells in correlation with morphometric data and inventory content9,11.
| Cell Type | Basal rate (per sec) | Initial maximal rate (per sec) | Granule diameter (nm) | Rosette size (K) | Granules per cell | Calcium cooperativity (M) |
|---|---|---|---|---|---|---|
| ANP | 6 | 100 | 350 | 16 | 240 | |
| Chromaffin cells | 1.5 | 1500 | 177 | 11 | 41000 | 3-5 |
| Enterochromaffin-like cells | 9 | 160 | 200 | 12 | 5200 | |
| Eosinophil | < 0.0008 | 0.6 | 500 | 20 | 400 | |
| Juxtaglomerular cell | 0.0005 | 0.017 | 1050 | 29 | 445 | |
| Mast cell (peritoneum) | 0.00024 | 0.8 | 500 | 20 | 1000 | 1-2 |
| Pancreatic acinar cell | 0.0033 | 0.62 | 600 | 22 | 1100 | 3 |
| Pancreatic β-cell | 0.01 | 14 | 305 | 15 | 11000 | 3-5 |
| Parotid | 0.0042 | 0.3-1 | 800 | 25 | 450 | 1-2 |
| Pituitary melanotroph | 0.45 | 25-450 | 160 | 11 | 20000 | 3 |
| Type II alveolar cell | 0.00037 | 0.04 | 1270 | 32 | 188 | 1-2 |