Efflux of Ca/sup 2 +/ and Mn/sup 2 +/ from rat liver mitochondria

Journal Article · Tue Jan 24 04:00:00 EST 1978 · Biochemistry; (United States)

OSTI ID:7090876

Gunter, T E; Gunter, K K; Puskin, J S; Russell, P R

Net efflux of Ca/sup 2 +/ and Mn/sup 2 +/ from previously loaded rat liver mitochondria has been studied. Several agents have been found which affect Ca/sup 2 +/ efflux and Mn/sup 2 +/ efflux differently. Rapid efflux of either Ca/sup 2 +/ or Mn/sup 2 +/ follows addition of sufficiently large amounts of an uncoupler such as carbonyl cyanide m-chlorophenylhydrazone (CCCP) to loaded mitochondria. Under these conditions, ruthenium red greatly retards Mn/sup 2 +/ but not Ca/sup 2 +/ efflux. Under similar conditions a chelating agent such as ethylene glycol bis(..beta..,/sup -/traacetic acid (EGTA) greatly retards Mn/sup 2 +/ but not Ca/sup 2 +/ efflux. Where very small amounts of CCCP are added to loaded mitochondria, on the other hand, Ca/sup 2 +/ efflux in the presence of EGTA can be significantly retarded. Furthermore, when rapid spontaneous Ca/sup 2 +/ efflux occurs, it is sometimes slowed or almost completely prevented by addition of small amounts of CCCP. The amount of CCCP which maximally inhibits Mn/sup 2 +/ efflux is approximately a factor of 20 higher than the amount which maximally inhibits Ca/sup 2 +/ efflux. Mn/sup 2 +/ efflux in the presence of EGTA or ruthenium red is greatly inhibited by metabolic inhibitors such as KCN while Ca/sup 2 +/ efflux is not. It is concluded that influx and efflux of Ca/sup 2 +/ and Mn/sup 2 +/ take place primarily through distinguishable mechanisms, and that the mechanisms facilitating the efflux of Ca/sup 2 +/ and Mn/sup 2 +/ are also distinct. Evidence is also presented supporting the hypothesis that Mn/sup 2 +/ efflux and perhaps Ca/sup 2 +/ efflux as well take place at least in part by means of an active mechanism.

• Research Organization: Univ. of Rochester, NY
• OSTI ID: 7090876
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 17:2; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550200 -- Biochemistry
550300 -- Cytology
551000* -- Physiological Systems
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
BIOCHEMICAL REACTION KINETICS
BODY
CALCIUM COMPOUNDS
CATIONS
CELL CONSTITUENTS
CELL MEMBRANES
CHARGED PARTICLES
CHELATING AGENTS
COMPARATIVE EVALUATIONS
CYANIDES
DIGESTIVE SYSTEM
DYES
ELECTRIC POTENTIAL
GLANDS
HYDRAZONES
IONS
KINETICS
LIVER
MAMMALS
MANGANESE COMPOUNDS
MEMBRANE TRANSPORT
MEMBRANES
MITOCHONDRIA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOIDS
ORGANS
POTASSIUM COMPOUNDS
RATS
REACTION KINETICS
RODENTS
TRANSITION ELEMENT COMPOUNDS
VERTEBRATES