Determination of Δψ, ΔpH and the proton electrochemical gradient in isolated cholinergic synaptic vesicles

Itzchak Angel, Daniel M. Michaelson

Research output: Contribution to journalArticlepeer-review

Abstract

The electrical potential (Δψ) of intact cholinergic synaptic vesicles was measured in the presence and absence of the proton translocator carbonyl cyanide p-trifluoromethoxy-phenylhydrazone (FCCP), and the results were utilized to calculate the vesicular proton chemical gradient (ΔpH) and proton electrochemical potential (ΔμH+). At external pH = 7.4 the vesicles maintain a proton electrochemical gradient of {reversed tilde equals}+20 mV (positive inside) which is composed of Δψ{reversed tilde equals}-80 mV (negative inside) and ΔpH{reversed tilde equals}1.6 (acidic inside). The proton chemical gradient (ΔpH) increases as a function of pHout whereas the vesicular electrical potential (Δψ) is only slightly affected by the external pH. Consequently, ΔμH+ is larger at basic external pH values ({reversed tilde equals}+40 mV at pHout = 9.0) and smaller at acidic external pH values (ΔμH+{reversed tilde equals}0 at (pHout = 5.6). The possible physiological role of the electrochemical potentials in maintaining high concentrations of acetylcholine within the cholinergic synaptic vesicle is discussed.

Original languageEnglish
Pages (from-to)411-416
Number of pages6
JournalLife Sciences
Volume29
Issue number4
DOIs
StatePublished - 27 Jul 1981

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