Mg2+ buffering in cultured chick ventricular myocytes: quantitation and modulation by Ca2+.

摘要: To characterize the Mg2+ buffering of cultured chick ventricular myocytes, cytosolic was increased by liberating normally chelated ATP upon total depletion content. Because Mg content and cell volume remained constant during this time, difference between amount liberated (2.7 mM) 0.9 mM increase in activity measured fluorometrically with mag-fura-2 indicates a sizable buffering. A new term, buffer coefficient (BMg), derived to quantify We also determined that only 0.6 cells acutely exposed zero external Ca2+ depletion. In absence extracellular Ca2+, basal (alpha Ca2+i) reduced 72%, whereas alpha Ca2+i induced substantially blunted; no either time course adenine nucleotide changes or Ca observed. The BMg value calculated for these is greater (2.5) than when present (1.4), indicating affects myocytes. Therefore myocytes appears be comprised at least two components: 1) Ca(2+)-insensitive pool 2) Ca(2+)-sensitive nonadenine pool.