Activity-dependent facilitation was studied in bovine adrenal chromaffin cells. Stimulation with a train of depolarizations caused subsequent triggered exocytotic activity to be significantly enhanced. After the facilitating stimulus train, the readily releasable vesicle pool (RRP) size was estimated from capacitance jumps in response to paired depolarizations and found to be elevated for a per...

In neurosecretory cells, intracellular Ca2+ ([Ca2+]i) not only acts as the trigger for secretion but also regulates earlier steps in the secretory pathway. Here, a novel approach was developed to control [Ca2+]i over a broad concentration range, which allowed the quantification of three distinct actions of [Ca2+]i on large dense-core vesicle (LDCV) fusion in chromaffin cells from mouse adrenal ...

We discuss a model of presynaptic vesicle dynamics, which allows for heterogeneity in release probability among vesicles. Specifically, we explore the possibility that synaptic activity is carried by two types of vesicles; first, a readily releasable pool and, second, a reluctantly releasable pool. The pools differ regarding their probability of release and time scales on which released vesicle...

Capacitance measurements were applied to mouse pancreatic beta-cells to elucidate the cellular mechanisms underlying biphasic insulin secretion. We report here that only <50 of the beta-cell's >10,000 granules are immediately available for release. The releasable granules tightly associate with the voltage-gated alpha(1C) Ca(2+) channels, and it is proposed that the release of these granules ac...

closure of donor site of the flap has special problems. reduction of this site will decrease the morbidity of operation. in this study, we present our experience in donor site size reduction. methods between 2006 and 2008, 15 patients with skin and soft tissue defects underwent operation. in all patients, coverage of defect was performed with various flaps. substratum horizontal mat-tress sutur...

OBJECTIVE Glucagon-like peptide-1 (GLP-1) rescues insulin secretory deficiency in type 2 diabetes partly via cAMP actions on exchange protein directly activated by cAMP (Epac2) and protein kinase A (PKA)-activated Rab3A-interacting molecule 2 (Rim2). We had reported that haplodeficient Munc13-1(+/-) mouse islet beta-cells exhibited reduced insulin secretion, causing glucose intolerance. Munc13-...

Under basal conditions the action potential firing rate of adrenal chromaffin cells is lower than 0.5 Hz. The maintenance of the secretory response at such frequencies requires a continuous replenishment of releasable vesicles. However, the mechanism that allows such vesicle replenishment remains unclear. Here, using membrane capacitance measurements on mouse chromaffin cells, we studied the me...

Neurons and neuroendocrine cells must retrieve plasma membrane excess and refill vesicle pools depleted by exocytosis. To perform these tasks cells can use different endocytosis/recycling mechanisms whose selection will impact on vesicle recycling time and secretion performance. We used FM1-43 to evaluate in the same experiment exocytosis, endocytosis, and recovery of releasable vesicles on mou...

Synaptotagmin-1 and -7 constitute the main calcium sensors mediating SNARE-dependent exocytosis in mouse chromaffin cells, but the role of a closely related calcium-binding protein, Doc2b, remains enigmatic. We investigated its role in chromaffin cells using Doc2b knock-out mice and high temporal resolution measurements of exocytosis. We found that the calcium dependence of vesicle priming and ...