Calcium and magnesium transport by in situ mitochondria: electron probe analysis of vascular smooth muscle

Journal Article · Thu Oct 01 04:00:00 EDT 1987 · Circ. Res.; (United States)

DOI:https://doi.org/10.1161/01.RES.61.4.523· OSTI ID:5620272

Broderick, R; Somlyo, A P

The extent, time course, and reversibility of mitochondrial Ca/sup 2 +/ uptake secondary to cellular Ca/sup 2 +/ influx stimulated by massive Na+ efflux were evaluated by electron probe microanalysis of rabbit portal vein smooth muscle. Strips of portal vein were Na+ loaded for 3 hours at 37/sup 0/C in a K+-free 1 mM ouabain solution, after which rapid Na+ efflux was induced by washing with a Na+-free K+-Li+ solution (1 mM ouabain). Li+ washing Na+-loaded portal vein produced a large transient contraction accompanied by an increase (over 100-fold) in mitochondrial Ca/sup 2 +/ and also significant (p less than 0.05) increases in phosphorus and Mg/sup 2 +/. The Ca/sup 2 +/ loading of the mitochondria was reversed during prolonged Li+ wash, and by 2 hours, mitochondrial Ca/sup 2 +/, Mg/sup 2 +/, and phosphorus had returned to control levels. The maximal contractile response to stimulation remained normal, demonstrating that pathologic Ca/sup 2 +/ loading of mitochondria is reversible in situ and compatible with normal maximal force developed by the smooth muscle. Mitochondrial Ca/sup 2 +/ and phosphorus uptake were reduced but still significant when the Li+ wash contained 0.2 mM Ca/sup 2 +/ or when ouabain was omitted. The fact that mitochondrial Ca/sup 2 +/ loading accompanied submaximal contractions during 0.2 mM Ca/sup 2 +/-Li wash suggests supranormal affinity of mitochondria for Ca/sup 2 +/ and may be due, in part, to reverse operation of the mitochondrial Na+-Ca/sup 2 +/ exchanger. Mitochondrial Ca/sup 2 +/, Mg/sup 2 +/, and phosphorus uptake were eliminated when the Li+ wash was performed at 2/sup 0/C or when the wash contained no Ca/sup 2 +/.

• Research Organization: Univ. of Pennsylvania School of Medicine, Philadelphia
• OSTI ID: 5620272
• Journal Information: Circ. Res.; (United States), Journal Name: Circ. Res.; (United States) Vol. 61:4; ISSN CIRUA
• Country of Publication: United States
• Language: English

Related Subjects

550500 -- Metabolism
560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
BODY TEMPERATURE
CALCIUM COMPOUNDS
CARBOHYDRATES
CARDIAC GLYCOSIDES
CARDIOTONICS
CARDIOVASCULAR AGENTS
CELL CONSTITUENTS
CHEMICAL ANALYSIS
DRUGS
ELECTRON MICROPROBE ANALYSIS
ELECTRONS
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
GLYCOSIDES
HYPOTHERMIA
LEPTONS
LITHIUM COMPOUNDS
MAGNESIUM COMPOUNDS
MAMMALS
MEMBRANE TRANSPORT
MICROANALYSIS
MITOCHONDRIA
MUSCLES
NONMETALS
ORGANIC COMPOUNDS
ORGANOIDS
OUABAIN
PHOSPHORUS
RABBITS
SODIUM COMPOUNDS
STROPHANTHINS
VERTEBRATES