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Polarographic observation of substrate‐level phosphorylation and its stimulation by acetylcholine
Author(s) -
Kondrashova M.N.,
Doliba N.M.
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)80119-x
Subject(s) - acetylcholine , phosphorylation , oxidative phosphorylation , stimulation , substrate (aquarium) , chemistry , polarography , substrate level phosphorylation , biochemistry , respiration , medicine , endocrinology , biology , inorganic chemistry , anatomy , ecology
Substrate‐level phosphorylation was observed under the conditions optimal for this process and opposite to those for oxidative phosphorylation. Polarographic registration of Ca 2+ stimulated α‐ketoglutarate oxidation and self‐inhibition of uncoupled α‐ketoglutarate (KG) oxidation was used. Acetylcholine (ACh) administration stimulated KG oxidation and substrate‐level phosphorylation in isolated mitochondria. These effects are stronger in tissues with a higher level of endogenous acetylcholine, such as guinea pig liver vs rat liver and pancreas vs liver. The specific stimulation of KG oxidation by ACh is related to a decrease of succinate oxidation and is contrary to the specific stimulating effect of adrenaline on succinate oxidation. Therefore the existence of reciprocal hormone‐substrate‐nucleotide systems is suggested. The described set of conditions optimal for substrate‐level phosphorylation observation by polarographic registration of respiration is as convenient as the ADP test for the investigation of oxidative phosphorylation.