Figure 2.
Under conditons of sustained depolarization, vesicle Ca loading is continuous but vesicle Na loading is transient. Average values of Cav and Nav in individual secretory vesicles of rapidly frozen isolated nerve endings. A significant increase in vesicular Ca content is demonstrated for secretory vesicles of potassium-stimulated nerve endings at 6 min as well as at 20 min, but an increase in intravesicular Na is recorded only after 6-min challenge. Significantly different from control values by Mann–Whitney test: ∗, P < 0.05; ∗∗, P < 0.001.