scholarly journals Exponential Fitting of Postextrasystolic Potentiation May Underestimate the Cardiac Ca2+ Recirculation Fraction: A Theoretical Analysis

2003 ◽  
Vol 53 (2) ◽  
pp. 89-96 ◽  
Author(s):  
Yumiko Doi ◽  
Junichi Araki ◽  
Waso Fujinaka ◽  
Takahiko Kiyooka ◽  
Yu Oshima ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Exponential Fitting ◽  
Postextrasystolic Potentiation ◽  
Recirculation Fraction

Energy-wasteful total Ca2+ handling underlies increased O2 cost of contractility in canine stunned heart

2000 ◽  
Vol 278 (5) ◽  
pp. H1464-H1472 ◽  
Author(s):  
Shinyu Lee ◽  
Junichi Araki ◽  
Takeshi Imaoka ◽  
Masaki Maesako ◽  
Gentaro Iribe ◽  
...  
Keyword(s):  
Exponential Decay ◽  
Myocardial Stunning ◽  
Left Ventricular ◽  
Canine Heart ◽  
Ventricular Contractility ◽  
Left Ventricular Contractility ◽  
Postextrasystolic Potentiation ◽  
Decay Component ◽  
Recirculation Fraction ◽  
Integrative Method

Postischemic myocardial stunning halved left ventricular contractility [end-systolic maximum elastance ( E max)] and doubled the O2 cost of E max in excised cross-circulated canine heart. We hypothesized that this increased O2 cost derived from energy-wasteful myocardial Ca2+ handling consisting of a decreased internal Ca2+ recirculation, some futile Ca2+ cycling, and a depressed Ca2+ reactivity of E max. We first calculated the internal Ca2+ recirculation fraction (RF) from the exponential decay component of postextrasystolic potentiation. Stunning significantly accelerated the decay and decreased RF from 0.63 to 0.43 on average. We then combined the decreased RF with the halved E maxand its doubled O2 cost and analyzed total Ca2+handling using our recently developed integrative method. We found a decreased total Ca2+ transport and a considerable shift of the relation between futile Ca2+ cycling and Ca2+ reactivity in an energy-wasteful direction in the stunned heart. These changes in total Ca2+ handling reasonably account for the doubled O2 cost of E max in stunning, supporting the hypothesis.

Temperature-dependent postextrasystolic potentiation and Ca2+ recirculation fraction in canine hearts

2002 ◽  
Vol 282 (2) ◽  
pp. H403-H413 ◽  
Author(s):  
Ju Mizuno ◽  
Junichi Araki ◽  
Shunsuke Suzuki ◽  
Satoshi Mohri ◽  
Takeshi Mikane ◽  
...  
Keyword(s):  
Left Ventricle ◽  
Exponential Decay ◽  
Temperature Sensitivity ◽  
Systolic Pressure ◽  
Volume Ratio ◽  
Myocardial Cells ◽  
Temperature Dependent ◽  
Postextrasystolic Potentiation ◽  
Decay Component ◽  
Recirculation Fraction

We have found that cardiac temperature proportionally changes O2 cost of contractility, defined as O2 consumption for myocardial total Ca2+handling normalized to contractility in terms of the end-systolic pressure-volume ratio (maximal elastance, E max), in the canine left ventricle (temperature sensitivity, Q10 = 2). We have separately found that a decrease in the recirculation fraction (RF) of Ca2+ within myocardial cells underlies an increased O2 cost of E max in stunned hearts. We therefore hypothesized that a similar change in RF would underlie the Q10 of O2 cost of E max. We tested this hypothesis by analyzing RF calculated from an exponential decay component of the transiently alternating postextrasystolic potentiation in the canine left ventricle. RF decreased from 0.7 to 0.5 as cardiac temperature increased from 33 to 38°C with Q10 of 0.5, reciprocal to that of O2 cost of E max. We conclude that Q10 of ATP-consuming reactions involved in Ca2+handling and E max response to it could reasonably account for the reciprocal Q10 of RF and O2 cost of E max.

scholarly journals New Calculation of Internal Ca2+ Recirculation Fraction from Alternans Decay of Postextrasystolic Potentiation.

2001 ◽  
Vol 51 (2) ◽  
pp. 143-149 ◽  
Author(s):  
Gentaro Iribe ◽  
Junichi Araki ◽  
Satoshi Mohri ◽  
Juichiro Shimizu ◽  
Takeshi Imaoka ◽  
...  
Keyword(s):  
Postextrasystolic Potentiation ◽  
Recirculation Fraction

Microdiffraction Patterns of Small Metallic Particles II; Theoretical Analysis

1982 ◽  
Vol 40 ◽  
pp. 668-669
Author(s):  
A. Gómez ◽  
P. Schabes-Retchkiman ◽  
M. José-Yacamán ◽  
T. Ocaña
Keyword(s):  
Experimental Data ◽  
Electron Diffraction ◽  
Theoretical Analysis ◽  
Size Range ◽  
Dynamical Theory ◽  
Metallic Particles ◽  
Splitting Effect

The splitting effect that is observed in microdiffraction pat-terns of small metallic particles in the size range 50-500 Å can be understood using the dynamical theory of electron diffraction for the case of a crystal containing a finite wedge. For the experimental data we refer to part I of this work in these proceedings.

Theoretical analysis of a monopole antenna with conducting flat disk above the earth

2001 ◽  
Vol 84 (7) ◽  
pp. 27-36
Author(s):  
Aki Yuasa ◽  
Daisuke Itatsu ◽  
Naoki Inagaki ◽  
Nobuyoshi Kikuma
Keyword(s):  
Theoretical Analysis ◽  
Monopole Antenna ◽  
The Earth ◽  
Flat Disk

Context Aversion, Pavlovian Conditioning, and the Psychological Side Effects of Chemotherapy

1997 ◽  
Vol 2 (2) ◽  
pp. 118-124
Author(s):  
Geoffrey Hall
Keyword(s):  
Animal Model ◽  
Side Effects ◽  
Theoretical Analysis ◽  
Conditioned Response ◽  
Behavioral Strategies ◽  
Contextual Cues ◽  
Anticipatory Nausea ◽  
Laboratory Rats ◽  
Anticipatory Nausea And Vomiting ◽  
Parallel Case

Patients who have undergone several sessions of chemotherapy for cancer will sometimes develop anticipatory nausea and vomiting (ANV), these unpleasant side effects occurring as the patients return to the clinic for a further session of treatment. Pavlov's analysis of learning allows that previously neutral cues, such as those that characterize a given place or context, can become associated with events that occur in that context. ANV could thus constitute an example of a conditioned response elicited by the contextual cues of the clinic. In order to investigate this proposal we have begun an experimental analysis of a parallel case in which laboratory rats are given a nausea-inducing treatment in a novel context. We have developed a robust procedure for assessing the acquisition of context aversion in rats given such training, a procedure that shows promise as a possible animal model of ANV. Theoretical analysis of the conditioning processes involved in the formation of context aversions in animals suggests possible behavioral strategies that might be used in the alleviation of ANV, and we report a preliminary experimental test of one of these.

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