Altered Ca fluxes and contractile state during pH changes in cultured heart cells
The authors studied mechanisms underlying changes in myocardial contractile state produced by intracellular (pH/sub i/) or extracellular (pH/sub 0/) changes in pH using cultured chick embryo ventricular cells. A change in pH/sub 0/ of HEPES-buffered medium from 7.4 to 6.0 or to 8.8 changed the amplitude of cell motion by -85 or +60%, and /sup 45/Ca uptake at 10 s by -29 or +22%, respectively. The pH/sub 0/ induced change in Ca uptake was not sensitive to nifedipine but was Na gradient dependent. Changes in pH/sub i/ produced by NH/sub 4/Cl or preincubation in media at pH values ranging from 6.0 to 8.8 failed to alter significantly /sup 45/Ca uptake or efflux. However, larger changes in pH/sub i/ were associated with altered Ca uptake. Changes in pH/sub 0/ from 7.5 to 6.0 or to 8.8 were associated with initial changes in /sup 45/Ca efflux by +17 or -18%, respectively, and these effects were not Na dependent. Exposure of cells to 20 mM NH/sub 4/Cl produced intracellular alkalinization and a positive inotropic effect, whereas subsequent removal of NH/sub 4/Cl caused intracellular acidification and a negative inotropic effect. There was, however, a lack of close temporal relationships between pH/sub i/ and contractile state. These results indicated that pH/sub 0/-induced changes in contractile state in cultured heart cells are closely correlated with altered transarcolemmal Ca movements and presumably are due to these Ca flux changes.
- Research Organization:
- Harvard Medical School, Boston, MA (USA)
- OSTI ID:
- 6244201
- Journal Information:
- Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 253:1; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ACIDIFICATION
ALKALI METAL COMPOUNDS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
AMINO ACIDS
AMMONIUM CHLORIDES
AMMONIUM COMPOUNDS
AMMONIUM HALIDES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIRDS
BODY
CALCIUM 45
CALCIUM COMPOUNDS
CALCIUM ISOTOPES
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
CATIONS
CELL CULTURES
CHARGED PARTICLES
CHICKENS
CHLORIDES
CHLORINE COMPOUNDS
DAYS LIVING RADIOISOTOPES
EMBRYOS
EVEN-ODD NUCLEI
FOWL
HALIDES
HALOGEN COMPOUNDS
HEART
INTERMEDIATE MASS NUCLEI
IONS
ISOTOPES
LABELLED COMPOUNDS
LEUCINE
MEMBRANE TRANSPORT
MUSCLES
MYOCARDIUM
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PH VALUE
PHYSIOLOGY
RADIOISOTOPES
SODIUM COMPOUNDS
TIME DEPENDENCE
TRITIUM COMPOUNDS
UPTAKE
VERTEBRATES