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), Journal Name: Am. J. Physiol.; (United States) Vol. 254; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL ISOTOPES
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
ANIMALS
ANOXIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIRDS
BODY
CALCIUM
CALCIUM 45
CALCIUM ISOTOPES
CARDIOVASCULAR SYSTEM
CATALASE
CELL CULTURES
CHICKENS
DAYS LIVING RADIOISOTOPES
ELEMENTS
EMBRYOS
ENZYMES
EVEN-ODD NUCLEI
FOWL
HEART
INTERMEDIATE MASS NUCLEI
ION EXCHANGE
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
METALS
MUSCLES
MYOCARDIUM
NUCLEI
ODD-ODD NUCLEI
ORGANS
OXIDOREDUCTASES
PEROXIDASES
RADICALS
RADIOISOTOPES
REACTION KINETICS
SECONDS LIVING RADIOISOTOPES
SODIUM 24
SODIUM ISOTOPES
SUPEROXIDE DISMUTASE
TRACER TECHNIQUES
UPTAKE
VERTEBRATES