Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Swelling and Contraction of Potato Mitochondria

Dennis W. Jung and Gerald P. Brierley
Plant Physiology
Vol. 64, No. 6 (Dec., 1979), pp. 948-953
Stable URL: http://www.jstor.org/stable/4266034
Page Count: 6
  • Read Online (Free)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Swelling and Contraction of Potato Mitochondria
Preview not available

Abstract

Mitochondria isolated from potato tubers fail to undergo passive osmotic swelling when suspended in isotonic Na+ acetate or phosphate, in NaCl following addition of tripropyltin, or in Na+ nitrate following addition of an uncoupler. Swelling under each of these conditions in mitochondria from other sources has been attributed to the inward movement of Na+ on an endogenous $Na^{+}/\text{H}^{+}$ exchanger. Such a monovalent cation/H+ exchanger has also been implicated in respiration-dependent cation extrusion and contraction of swollen mitochondria. Potato mitochondria swollen in chloride and nitrate salts extrude ions and contract when respiration is initiated. The contraction reaction is slower and less efficient than that in beef heart mitochondria, but like the latter, is sensitive to uncouplers and stimulated by nigericin, butacaine, and Mg2+. These comparative studies suggest that a $\text{cation}^{+}/\text{H}^{+}$ exchanger is present in potato tuber mitochondria, but that it functions exclusively as a cation-extruding mechanism. They further suggest that $\text{cation}^{+}/\text{H}^{+}$ exchange activity is not identical in mitochondria from different sources and that these exchange components may have a directionality and regulatory features which differ with the metabolic needs of the source tissue.

Page Thumbnails

  • Thumbnail: Page 
948
    948
  • Thumbnail: Page 
949
    949
  • Thumbnail: Page 
950
    950
  • Thumbnail: Page 
951
    951
  • Thumbnail: Page 
952
    952
  • Thumbnail: Page 
953
    953