Impact of physiological variables and genetic background on myocardial frequency-resistivity relations in the intact beating murine heart

Maricela Reyes, Mark E. Steinhelper, Jorge A. Alvarez, Daniel Escobedo, John Pearce, Jonathan W. Valvano, Bradley H Pollock, Chia Ling Wei, Anil Kottam, David Altman, Steven Bailey, Sharon Thomsen, Shuko Lee, James T. Colston, Hwan Oh Jung, Gregory L. Freeman, Marc D. Feldman

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Conductance measurements for generation of an instantaneous left ventricular (LV) volume signal in the mouse are limited, because the volume signal is a combination of blood and LV muscle, and only the blood signal is desired. We have developed a conductance system that operates at two simultaneous frequencies to identify and remove the myocardial contribution to the instantaneous volume signal. This system is based on the observation that myocardial resistivity varies with frequency, whereas blood resistivity does not. For calculation of LV blood volume with the dual-frequency conductance system in mice, in vivo murine myocardial resistivity was measured and combined with an analytic approach. The goals of the present study were to identify and minimize the sources of error in the measurement of myocardial resistivity to enhance the accuracy of the dual-frequency conductance system. We extended these findings to a gene-altered mouse model to determine the impact of measured myocardial resistivity on the calculation of LV pressure-volume relations. We examined the impact of temperature, timing of the measurement during the cardiac cycle, breeding strain, anisotropy, and intrameasurement and interanimal variability on the measurement of intact murine myocardial resistivity. Applying this knowledge to diabetic and nondiabetic 11- and 20- to 24-wk-old mice, we demonstrated differences in myocardial resistivity at low frequencies, enhancement of LV systolic function at 11 wk and LV dilation at 20-24 wk, and histological and electron-microscopic studies demonstrating greater glycogen deposition in the diabetic mice. This study demonstrated the accurate technique of measuring myocardial resistivity and its impact on the determination of LV pressure-volume relations in gene-altered mice.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume291
Issue number4
DOIs
StatePublished - 2006
Externally publishedYes

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Ventricular Pressure
Anisotropy
Blood Volume
Glycogen
Left Ventricular Function
Genes
Breeding
Genetic Background
Dilatation
Research Design
Electrons
Muscles
Temperature

Keywords

  • Diabetes
  • Dual-frequency conductance method
  • Gene-altered mouse
  • Left ventricular volume
  • Myocardial resistivity

ASJC Scopus subject areas

  • Physiology

Cite this

Impact of physiological variables and genetic background on myocardial frequency-resistivity relations in the intact beating murine heart. / Reyes, Maricela; Steinhelper, Mark E.; Alvarez, Jorge A.; Escobedo, Daniel; Pearce, John; Valvano, Jonathan W.; Pollock, Bradley H; Wei, Chia Ling; Kottam, Anil; Altman, David; Bailey, Steven; Thomsen, Sharon; Lee, Shuko; Colston, James T.; Jung, Hwan Oh; Freeman, Gregory L.; Feldman, Marc D.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 291, No. 4, 2006.

Research output: Contribution to journalArticle

Reyes, M, Steinhelper, ME, Alvarez, JA, Escobedo, D, Pearce, J, Valvano, JW, Pollock, BH, Wei, CL, Kottam, A, Altman, D, Bailey, S, Thomsen, S, Lee, S, Colston, JT, Jung, HO, Freeman, GL & Feldman, MD 2006, 'Impact of physiological variables and genetic background on myocardial frequency-resistivity relations in the intact beating murine heart', American Journal of Physiology - Heart and Circulatory Physiology, vol. 291, no. 4. https://doi.org/10.1152/ajpheart.00609.2005
Reyes, Maricela ; Steinhelper, Mark E. ; Alvarez, Jorge A. ; Escobedo, Daniel ; Pearce, John ; Valvano, Jonathan W. ; Pollock, Bradley H ; Wei, Chia Ling ; Kottam, Anil ; Altman, David ; Bailey, Steven ; Thomsen, Sharon ; Lee, Shuko ; Colston, James T. ; Jung, Hwan Oh ; Freeman, Gregory L. ; Feldman, Marc D. / Impact of physiological variables and genetic background on myocardial frequency-resistivity relations in the intact beating murine heart. In: American Journal of Physiology - Heart and Circulatory Physiology. 2006 ; Vol. 291, No. 4.
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AU - Reyes, Maricela

AU - Steinhelper, Mark E.

AU - Alvarez, Jorge A.

AU - Escobedo, Daniel

AU - Pearce, John

AU - Valvano, Jonathan W.

AU - Pollock, Bradley H

AU - Wei, Chia Ling

AU - Kottam, Anil

AU - Altman, David

AU - Bailey, Steven

AU - Thomsen, Sharon

AU - Lee, Shuko

AU - Colston, James T.

AU - Jung, Hwan Oh

AU - Freeman, Gregory L.

AU - Feldman, Marc D.

PY - 2006

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N2 - Conductance measurements for generation of an instantaneous left ventricular (LV) volume signal in the mouse are limited, because the volume signal is a combination of blood and LV muscle, and only the blood signal is desired. We have developed a conductance system that operates at two simultaneous frequencies to identify and remove the myocardial contribution to the instantaneous volume signal. This system is based on the observation that myocardial resistivity varies with frequency, whereas blood resistivity does not. For calculation of LV blood volume with the dual-frequency conductance system in mice, in vivo murine myocardial resistivity was measured and combined with an analytic approach. The goals of the present study were to identify and minimize the sources of error in the measurement of myocardial resistivity to enhance the accuracy of the dual-frequency conductance system. We extended these findings to a gene-altered mouse model to determine the impact of measured myocardial resistivity on the calculation of LV pressure-volume relations. We examined the impact of temperature, timing of the measurement during the cardiac cycle, breeding strain, anisotropy, and intrameasurement and interanimal variability on the measurement of intact murine myocardial resistivity. Applying this knowledge to diabetic and nondiabetic 11- and 20- to 24-wk-old mice, we demonstrated differences in myocardial resistivity at low frequencies, enhancement of LV systolic function at 11 wk and LV dilation at 20-24 wk, and histological and electron-microscopic studies demonstrating greater glycogen deposition in the diabetic mice. This study demonstrated the accurate technique of measuring myocardial resistivity and its impact on the determination of LV pressure-volume relations in gene-altered mice.

AB - Conductance measurements for generation of an instantaneous left ventricular (LV) volume signal in the mouse are limited, because the volume signal is a combination of blood and LV muscle, and only the blood signal is desired. We have developed a conductance system that operates at two simultaneous frequencies to identify and remove the myocardial contribution to the instantaneous volume signal. This system is based on the observation that myocardial resistivity varies with frequency, whereas blood resistivity does not. For calculation of LV blood volume with the dual-frequency conductance system in mice, in vivo murine myocardial resistivity was measured and combined with an analytic approach. The goals of the present study were to identify and minimize the sources of error in the measurement of myocardial resistivity to enhance the accuracy of the dual-frequency conductance system. We extended these findings to a gene-altered mouse model to determine the impact of measured myocardial resistivity on the calculation of LV pressure-volume relations. We examined the impact of temperature, timing of the measurement during the cardiac cycle, breeding strain, anisotropy, and intrameasurement and interanimal variability on the measurement of intact murine myocardial resistivity. Applying this knowledge to diabetic and nondiabetic 11- and 20- to 24-wk-old mice, we demonstrated differences in myocardial resistivity at low frequencies, enhancement of LV systolic function at 11 wk and LV dilation at 20-24 wk, and histological and electron-microscopic studies demonstrating greater glycogen deposition in the diabetic mice. This study demonstrated the accurate technique of measuring myocardial resistivity and its impact on the determination of LV pressure-volume relations in gene-altered mice.

KW - Diabetes

KW - Dual-frequency conductance method

KW - Gene-altered mouse

KW - Left ventricular volume

KW - Myocardial resistivity

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