• DOI:10.1111/j.1469-7793.1997.481bj.x
• Corpus ID: 19603541

Drastic facilitation by α‐latrotoxin of bovine chromaffin cell exocytosis without measurable enhancement of Ca2+ entry or [Ca2+]i

@article{Michelena1997DrasticFB,
  title={Drastic facilitation by $\alpha$‐latrotoxin of bovine chromaffin cell exocytosis without measurable enhancement of Ca2+ entry or [Ca2+]i},
  author={Pedro Michelena and Mar{\'i}a‐Teresa Fuente and Teresa Vega and Baldomero Lara and Manuela G. L{\'o}pez and Luis Gand{\'i}a and Antonio G. Garc{\'i}a},
  journal={The Journal of Physiology},
  year={1997},
  volume={502}
}

• P. Michelena, María‐Teresa Fuente, +4 authors Antonio G. García
• Published 1 August 1997
• Biology
• The Journal of Physiology

1 Latrotoxin (LTX, 1–3 nm) caused a gradual increase of the supontaneous catecholamine release rate in bovine adrenal chromaffin cells superfused with normal Krebs–Hepes solution containing 2.5 mm Ca2+. Ca2+ removal abolished this effect. LTX enhanced also the secretory responses to high K+ (35 or 70 mm) and to acetylcholine (ACh, 30 μm). 2 The application of Ca2+ pulses to cells previously superfused with a 0 Ca2+ solution (Krebs–Hepes deprived of CaCl2) induced secretory responses that gradually reached 400–800 nA of catecholamines, provided that LTX was present. The responses to ACh or 35 mm K+ pulses (in the presence of Ca2+) were also enhanced by LTX, from around 100–200 nA to over 1000 nA. Though such enhancement remained in the presence of Ca2+ channel blockers, it disappeared upon the lowering of [Na+]0 or in electroporated cells. 3 Using protocols similar to those of secretion, LTX did not enhance basal 45Ca2+ uptake, whole‐cell Ca2+ currents or basal [Ca2+]j. In fact, LTX attenuated the K+‐ or ACh‐evoked increases in 45Ca2+ uptake and [Ca2+]1. 4 It is proposed that the secretory response to brief periods of Ca2+ reintroductions is triggered by local subplasmalemmal Ca2+1 tranMents, produced by the Na+‐Ca2+ exchanger of the plasma membrane working in the reverse mode. This situation might be physiologically reproduced during ACh stimulation of chromaffin cells, which is followed by the firing of Na+‐dependent action potentials.