title: Vesicular ATPase inserted into the plasma membrane of motor terminals by exocytosis alkalinizes cytosolic pH and facilitates endocytosis.
abstract: Key components of vesicular neurotransmitter release, such as Ca(2+) influx and membrane recycling, are affected by cytosolic pH. We measured the pH-sensitive fluorescence of Yellow Fluorescent Protein transgenically expressed in mouse motor nerve terminals, and report that Ca(2+) influx elicited by action potential trains (12.5-100 Hz) evokes a biphasic pH change: a brief acidification (∼ 13 nM average peak increase in [H(+)]), followed by a prolonged alkalinization (∼ 30 nM peak decrease in [H(+)]) that outlasts the stimulation train. The alkalinization is selectively eliminated by blocking vesicular exocytosis with botulinum neurotoxins, and is prolonged by the endocytosis-inhibitor dynasore. Blocking H(+) pumping by vesicular H(+)-ATPase (with folimycin or bafilomycin) suppresses stimulation-induced alkalinization and reduces endocytotic uptake of FM1-43. These results suggest that H(+)-ATPase, known to transfer cytosolic H(+) into prefused vesicles, continues to extrude cytosolic H(+) after being exocytotically incorporated into the plasma membrane. The resulting cytosolic alkalinization may facilitate vesicular endocytosis.
authors.affiliation: Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
authors.forename: Zhongsheng
authors.initials: Z
authors.lastname: Zhang
authors.forename: Khanh T
authors.initials: KT
authors.lastname: Nguyen
authors.forename: Ellen F
authors.initials: EF
authors.lastname: Barrett
authors.forename: Gavriel
authors.initials: G
authors.lastname: David
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002462:Cell Membrane / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology*; D005089:Exocytosis / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D051379:Mice; D008822:Mice, Transgenic; D017729:Presynaptic Terminals / Q000201:enzymology*; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D013572:Synaptic Vesicles / Q000201:enzymology*
chemical_list: D006180:Proton-Translocating ATPases