PT  - JOURNAL ARTICLE
AU  - Clark A. Lindgren
AU  - Dennis G. Emery
AU  - Philip G. Haydon
TI  - Intracellular Acidification Reversibly Reduces Endocytosis at the Neuromuscular Junction
AID  - 10.1523/JNEUROSCI.17-09-03074.1997
DP  - 1997 May 01
TA  - The Journal of Neuroscience
PG  - 3074--3084
VI  - 17
IP  - 9
4099  - http://www.jneurosci.org/content/17/9/3074.short
4100  - http://www.jneurosci.org/content/17/9/3074.full
SO  - J. Neurosci.1997 May 01; 17
AB  - The close spatial and temporal coupling of endocytosis and exocytosis in nerve terminals has made it difficult to elucidate the mechanisms and the regulation of endocytosis per se. Despite significant advances in our knowledge of the molecules involved in endocytosis, it has not yet been possible to selectively manipulate endocytosis in nerve terminals. We report that the substitution of propionate for chloride in the saline bathing a lizard neuromuscular junction reduces internal pH and reversibly blocks activity-dependent endocytosis. When intraterminal pH is reduced by ∼0.7 pH units, the uptake of FM1-43 in nerve terminals, but not activity-dependent destaining, is reduced. Normalization of intracellular pH by removing the propionate, raising extracellular pH, or adding ammonium chloride immediately restores FM1-43 uptake. Electron microscopy indicates that intracellular acidification reversibly reduces activity-dependent endocytosis in nerve terminals, because depolarization in propionate saline leads to a depletion of vesicles and the appearance of large intramembraneous infoldings.