Mechanisms of reoxygenation-induced calcium overload in cultured chick embryo heart cells
We examined mechanisms by which Ca enters cultured myocardial cells during posthypoxic reoxygenation. Monolayer cultures of chick embryo ventricular cells were prepared from hearts 10 days in ovo. Cells were exposed to hypoxic conditions (PO/sub 2/ less than 1.5 Torr), and /sup 45/Ca uptake during subsequent reoxygenation was then examined in the absence and presence of modulators of Ca channel-dependent Ca entry and Na-Ca exchange. Modulation of Ca entry by free radical-scavenging enzymes was also examined. Hypoxia for 120 min followed by reoxygenation increased Ca content from 1.9 to 6.1 nmol/mg protein (P less than 0.05) at 30 min. Verapamil (10(-5) M) added before reoxygenation reduced Ca overload to 3.1 +/- 0.2 nmol/mg protein (P less than 0.05), but both verapamil and BAY K 8644 were without effect on modulating Ca entry if added 30 min after reoxygenation. /sup 24/Na content of cells increased from 70 nmol/mg protein in control cells to 157 nmol/mg protein (P less than 0.05) after hypoxia and reoxygenation, favoring Ca entry via Na-Ca exchange. Dichlorobenzamil significantly ameliorated reoxygenation-induced Ca overload, as did catalase and superoxide dismutase. We conclude that reoxygenation-induced Ca overload is unlikely to occur via the Ca channel. It occurs in part via Na-Ca exchange and is substantially ameliorated by enzymatic O/sub 2/ free radical scavengers.
- Research Organization:
- Brigham and Women's Hospital and Harvard Medical School, Boston, MA (USA)
- OSTI ID:
- 6975013
- Journal Information:
- Am. J. Physiol.; (United States), Vol. 254
- Country of Publication:
- United States
- Language:
- English
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UPTAKE
ANOXIA
BIOCHEMICAL REACTION KINETICS
CALCIUM 45
CATALASE
CELL CULTURES
CHICKENS
EMBRYOS
HEART
ION EXCHANGE
MYOCARDIUM
RADICALS
SODIUM 24
SUPEROXIDE DISMUTASE
TRACER TECHNIQUES
ALKALI METAL ISOTOPES
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIRDS
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CARDIOVASCULAR SYSTEM
DAYS LIVING RADIOISOTOPES
ELEMENTS
ENZYMES
EVEN-ODD NUCLEI
FOWL
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
METALS
MUSCLES
NUCLEI
ODD-ODD NUCLEI
ORGANS
OXIDOREDUCTASES
PEROXIDASES
RADIOISOTOPES
REACTION KINETICS
SECONDS LIVING RADIOISOTOPES
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550201* - Biochemistry- Tracer Techniques