TY - JOUR
T1 - Intracellular [Ca2+] related to rate of force development in twitch contraction of heart
AU - Yue, D. T.
PY - 1987
Y1 - 1987
N2 - The relation between the rate of rise of tension (dF/dt) and intracellular free Ca2+ concentration ([Ca2+](i)) during twitch contraction was investigated in mammalian ventricular myocardium. [Ca2+](i) was assessed from luminescence emitted by ferret papillary muscles microinjected with the calcium-regulated photoprotein aequorin. Evidence was found that during the phase of rising tension following maximum positive dF/dt, there was an approximately linear relationship between dF/dt at a given instant and the estimated [Ca2+](i) at that same instant. A single such instantaneous relationship held true for physiological contractions of widely varying strength (n = 5 preparations), up to 65.3 ± 6.0% (means ± SE) of maximal Ca2+-activated force, as assessed from maximally activated cardiac tetani. Furthermore, the identical relationship determined from physiological contractions also held true for virtually the entire rising phase of tension in contractions with [Ca2+](i) transients slowed (~4- to 5-fold) by exposure of muscles to 5 μM ryanodine (n = 5 preparations). That a unique relation applies to contractions of both vastly different strength and time course provides evidence that the correlation between instantaneous dF/dt and [Ca2+](i) is not merely fortuitous but indicates a fundamental property of myocardium. Such a property provides considerable insight into many features of physiological contraction and may represent a central clue as to the mechanism of activation in mammalian cardiac muscles.
AB - The relation between the rate of rise of tension (dF/dt) and intracellular free Ca2+ concentration ([Ca2+](i)) during twitch contraction was investigated in mammalian ventricular myocardium. [Ca2+](i) was assessed from luminescence emitted by ferret papillary muscles microinjected with the calcium-regulated photoprotein aequorin. Evidence was found that during the phase of rising tension following maximum positive dF/dt, there was an approximately linear relationship between dF/dt at a given instant and the estimated [Ca2+](i) at that same instant. A single such instantaneous relationship held true for physiological contractions of widely varying strength (n = 5 preparations), up to 65.3 ± 6.0% (means ± SE) of maximal Ca2+-activated force, as assessed from maximally activated cardiac tetani. Furthermore, the identical relationship determined from physiological contractions also held true for virtually the entire rising phase of tension in contractions with [Ca2+](i) transients slowed (~4- to 5-fold) by exposure of muscles to 5 μM ryanodine (n = 5 preparations). That a unique relation applies to contractions of both vastly different strength and time course provides evidence that the correlation between instantaneous dF/dt and [Ca2+](i) is not merely fortuitous but indicates a fundamental property of myocardium. Such a property provides considerable insight into many features of physiological contraction and may represent a central clue as to the mechanism of activation in mammalian cardiac muscles.
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U2 - 10.1152/ajpheart.1987.252.4.h760
DO - 10.1152/ajpheart.1987.252.4.h760
M3 - Article
C2 - 3565592
AN - SCOPUS:0023318184
SN - 0363-6135
VL - 252
SP - H760-H770
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 4 (21/4)
ER -