Myoplasmic free calcium concentration reached during the twitch of an intact isolated cardiac cell and during calcium-induced release of calcium from the sarcoplasmic reticulum of a skinned cardiac cell from the adult rat or rabbit ventricle.

摘要: Intact cardiac cells from the adult rat or rabbit ventricle were isolated by enzymatic digestion with a progressive increase of [free Ca2+] in solution. These electrically stimulated presence 2.50 mM free Ca2+, and twitch maximum amplitude was elicited positive inotropic interventions that found to be optimum. Then chemically skinned, tension induced saturating used as reference express developed during intact cells. The myoplasmic reached inferred tension-pCa curve. In mechanically skinned same animal species, Ca2+-induced release Ca2+ sarcoplasmic reticulum (SR) two methods using (a) curve (b) direct calibration transients aequorin bioluminescence. induction SR required larger preload higher trigger than However, results obtained inference suggest both species pCa approximately 5.40 optimum This much lower necessary for full activation myofilaments (pCa 4.90).