TY - JOUR

T1 - Half-logistic function model for first half of descending phase of cardiomyocyte cytoplasmic ca2+ concentration ([ca2+]i)-time curve (catciii) in isolated aequorin-injected mouse left ventricular papillary muscle

AU - Mizuno, Ju

AU - Otsuji, Mikiya

AU - Yokoyama, Takeshi

AU - Arita, Hideko

AU - Hanaoka, Kazuo

PY - 2016/1

Y1 - 2016/1

N2 - Background: Myocardial contraction and relaxation are regulated by increases and decreases in cytoplasmic calcium concentration ([Ca2+]i). In previous studies, we found that a half-logistic (h-L) function, which represents a half-curve of a symmetrical sigmoid logistic function with a boundary at the inflection point, curve-fits the first half of the ascending phase and the second half of the descending phase of the [Ca2+]i transient curve better than a mono-exponential (m-E) function. In the present study,we investigated the potential application of an h-L function to analyse the first half of the descending phase of CaTC (CaTCIII). Methods: The [Ca2+]i was measured using the Ca2+-sensitive aequorin, which was microinjected into 15 isolated mouse left ventricular (LV) papillary muscles. The observed CaTCIII data in the interval from the point corresponding to the peak [Ca2+]i to the point corresponding to dCa/dtmin was curve-fitted using the h-L and m-E function equations by the least-squares method. Results: The mean correlation coefficient (r) values of the h-L and m-E function best curve-fits for 11 CaTCIIIs were 0.9986 and 0.9982, respectively. The Z transformation of h-L r (3.64 ± 0.45) was larger than that of m-E r (3.50 ± 0.33) (p < 0.05). Conclusions: The h-L function can evaluate most CaTCIIIs more accurately than the m-E function in isolated aequorin-injected mouse LV papillary muscle. The three calculated h-L parameters i.e., amplitude constant, time constant, and non-zero asymptote, are more reliable indices than m-E for evaluating the magnitude and time course of the change in the decrease in [Ca2+]i.

AB - Background: Myocardial contraction and relaxation are regulated by increases and decreases in cytoplasmic calcium concentration ([Ca2+]i). In previous studies, we found that a half-logistic (h-L) function, which represents a half-curve of a symmetrical sigmoid logistic function with a boundary at the inflection point, curve-fits the first half of the ascending phase and the second half of the descending phase of the [Ca2+]i transient curve better than a mono-exponential (m-E) function. In the present study,we investigated the potential application of an h-L function to analyse the first half of the descending phase of CaTC (CaTCIII). Methods: The [Ca2+]i was measured using the Ca2+-sensitive aequorin, which was microinjected into 15 isolated mouse left ventricular (LV) papillary muscles. The observed CaTCIII data in the interval from the point corresponding to the peak [Ca2+]i to the point corresponding to dCa/dtmin was curve-fitted using the h-L and m-E function equations by the least-squares method. Results: The mean correlation coefficient (r) values of the h-L and m-E function best curve-fits for 11 CaTCIIIs were 0.9986 and 0.9982, respectively. The Z transformation of h-L r (3.64 ± 0.45) was larger than that of m-E r (3.50 ± 0.33) (p < 0.05). Conclusions: The h-L function can evaluate most CaTCIIIs more accurately than the m-E function in isolated aequorin-injected mouse LV papillary muscle. The three calculated h-L parameters i.e., amplitude constant, time constant, and non-zero asymptote, are more reliable indices than m-E for evaluating the magnitude and time course of the change in the decrease in [Ca2+]i.

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U2 - 10.6515/ACS20150424G

DO - 10.6515/ACS20150424G

M3 - Article

AN - SCOPUS:84955322427

SN - 1011-6842

VL - 32

SP - 65

EP - 74

JO - Acta Cardiologica Sinica

JF - Acta Cardiologica Sinica

IS - 1

ER -