Enhancement of secretion by threshold nicotinic stimulation in bovine chromaffin cells.

: Synaptic release of neurotransmitters displays activity-dependent changes such as enhancement (facilitation, augmentation, or potentiation) or diminution (depression), which have been studied widely because of their implication in synaptic efficacy, neuronal plasticity, and formation and consolidation of learning and memory. Some of these types of modulation of secretion displayed by neurons are also present in neuroendocrine chromaffin cells, for instance, facilitation or augmentation, which seem to be related to mild changes in the transients of cytosolic concentration of calcium ([Ca2+]i) and the degree of refilling of the primed vesicle pool (Zucker, 1996; Neher, 1998). Desensitized nicotinic acetylcholine receptors (nAChRs) and their possible role in this short-term synaptic plasticity was investigated in populations of bovine chromaffin cells.