Ion transport by heart mitochondria

On the "Energized-Twisted" Configuration of Isolated Beef Heart Mitochondria

“…3 C. This may explain the fact that Deamer et al (29) were able to fix the matrix expanded and the contracted states of liver mitochondria by direct addition of glutaraldehyde with little subsequent swelling or contraction. These studies and others (2,(21)(22)(23)(24)(29)(30)(31) have firmly established the close relationship between matrix expansion and ion accumulation. It should be noted that fixation of isolated mitochondria with glutaraldehyde in sucrose media does not result in contraction if osmotic equilibrium is established before the addition of the fixative (see reference 3 and reference 30, Fig.…”

“…These results confirm the reports of Green and coworkers (7)(8)(9)(10)(11)(12) as to the conditions necessary to establish the energlzed-twisted configuration. It is of interest to note, however, that these are also the conditions which support the spontaneous accumulation of monovalent cations and phosphate (21)(22)(23)(24). In this regard Fig.…”

“…1 A following the addition of phosphate). Heart mitochondria accumulate choline under similar conditions (21). It is now clear that isolated heart mitochondria are capable of accumulating large amounts of phosphate and acetate salts in the absence of added ionophores by a respiration-dependent reaction, and that this uptake of salts results in osmotic swelling (21)(22)(23)(24).…”

“…Heart mitochondria accumulate choline under similar conditions (21). It is now clear that isolated heart mitochondria are capable of accumulating large amounts of phosphate and acetate salts in the absence of added ionophores by a respiration-dependent reaction, and that this uptake of salts results in osmotic swelling (21)(22)(23)(24). In a medium containing sucrose the osmotic pressure of the nonpenetrating sucrose strongly opposes this respiration-dependent osmotic swelling so that the net phosphate accumulation and osmotic expansion of the matrix are limited.…”

SLC9 Gene Family: Function, Expression, and Regulation

“…Since the original descriptions of the Na + /H + exchange mechanism by Mitchell and Moyle (196) and by Brierley et al (37) in rat liver and cow heart mitochondria, respectively, the field has quickly expanded to describe Na + /H + exchange in both prokaryotic, plant, and other eukaryotic organisms, and to clone and molecularly and functionally characterize multiple isoforms of Na + /H + exchangers. While the basic principle of Na + /H + exchange is consistent across domains, procaryotes, plants, and yeasts evolved to utilize Na + /H + exchange to cope with extreme hypersaline or hyperalkaline conditions, where Na + /H + exchange mechanisms lead to the net uptake of protons and net loss of sodium.…”