ISSN:
1573-6881
Keywords:
Mitochondria
;
K+/H+ antiport
;
mitochondrial swelling
;
mitochondrial contraction
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Physics
Notes:
Abstract Mitochondria contain a latent K+/H+ antiporter that is activated by Mg2+-depletion and shows optimal activity in alkaline, hypotonic suspending media. This K+/H+ antiport activity appears responsible for a respiration-dependent extrusion of endogenous K+, for passive swelling in K+ acetate and other media, for a passive exchange of matrix42K+ against external K+, Na+, or Li+, and for the respiration-dependent ion extrusion and osmotic contraction of mitochondria swollen passively in K+ nitrate. K+/H+ antiport is inhibited by quinine and by dicyclohexylcarbodiimide when this reagent is reacted with Mg2+-depleted mitochondria. There is good suggestive evidence that the K+/H+ antiport may serve as the endogenous K+-extruding device of the mitochondrion. There is also considerable experimental support for the concept that the K+/H+ antiport is regulated to prevent futile influx-efflux cycling of K+. However, it is not yet clear whether such regulation depends on matrix free Mg2+, on membrane conformational changes, or other as yet unknown factors.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00768394
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