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Reduced mechanical efficiency in left-ventricular trabeculae of the spontaneously hypertensive rat.

Han JC, Tran K, Johnston CM, Nielsen PM, Barrett CJ, Taberner AJ, Loiselle DS - Physiol Rep (2014)

Bottom Line: Our results show that, whereas the performance of the SHR-F differed little from that of the SHR-NF, both SHR groups performed less stress-length work than that of Wistar trabeculae.Their lower work output arose from reduced ability to produce sufficient force and shortening.Consequently, mechanical efficiency (the ratio of work to change of enthalpy) of both SHR groups was lower than that of the Wistar trabeculae.

View Article: PubMed Central - PubMed

Affiliation: Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.

No MeSH data available.


Related in: MedlinePlus

Raw records of work‐loop contractions from representative trabeculae. (A) Isometric twitch (a) superimposed with seven work‐loop twitches of various afterloads (b–h). (B) Corresponding length change throughout the time‐course of twitches in A. Gray circles indicate locations at which velocities of muscle shortening were maximal. (C) Parametric plots of the data in A against those in B. The area within the stress‐length loop quantifies work output, as calculated by integrating stress as a function of L/Lo over the entire period of the twitch. Note that for the isometric contraction (“a”), work output is zero. (D) Rate of heat production for seven variously‐afterloaded work‐loop contractions (b–h), bracketed by eight isometric contractions (a).
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fig04: Raw records of work‐loop contractions from representative trabeculae. (A) Isometric twitch (a) superimposed with seven work‐loop twitches of various afterloads (b–h). (B) Corresponding length change throughout the time‐course of twitches in A. Gray circles indicate locations at which velocities of muscle shortening were maximal. (C) Parametric plots of the data in A against those in B. The area within the stress‐length loop quantifies work output, as calculated by integrating stress as a function of L/Lo over the entire period of the twitch. Note that for the isometric contraction (“a”), work output is zero. (D) Rate of heat production for seven variously‐afterloaded work‐loop contractions (b–h), bracketed by eight isometric contractions (a).

Mentions: Work‐loop contractions (Fig. 4), simplified versions of the contraction patterns of the heart, allow quantification of shortening‐related parameters (Fig. 5) and stress‐length work output (Figs. 4C, 7A). Coupled with simultaneous measurement of heat production (Figs. 4D, 6), work‐loop contractions allow quantification of enthalpy output (the sum of work and heat; Fig. 6) and hence mechanical efficiency (the ratio of work to enthalpy output; Fig. 7B and C).


Reduced mechanical efficiency in left-ventricular trabeculae of the spontaneously hypertensive rat.

Han JC, Tran K, Johnston CM, Nielsen PM, Barrett CJ, Taberner AJ, Loiselle DS - Physiol Rep (2014)

Raw records of work‐loop contractions from representative trabeculae. (A) Isometric twitch (a) superimposed with seven work‐loop twitches of various afterloads (b–h). (B) Corresponding length change throughout the time‐course of twitches in A. Gray circles indicate locations at which velocities of muscle shortening were maximal. (C) Parametric plots of the data in A against those in B. The area within the stress‐length loop quantifies work output, as calculated by integrating stress as a function of L/Lo over the entire period of the twitch. Note that for the isometric contraction (“a”), work output is zero. (D) Rate of heat production for seven variously‐afterloaded work‐loop contractions (b–h), bracketed by eight isometric contractions (a).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4255817&req=5

fig04: Raw records of work‐loop contractions from representative trabeculae. (A) Isometric twitch (a) superimposed with seven work‐loop twitches of various afterloads (b–h). (B) Corresponding length change throughout the time‐course of twitches in A. Gray circles indicate locations at which velocities of muscle shortening were maximal. (C) Parametric plots of the data in A against those in B. The area within the stress‐length loop quantifies work output, as calculated by integrating stress as a function of L/Lo over the entire period of the twitch. Note that for the isometric contraction (“a”), work output is zero. (D) Rate of heat production for seven variously‐afterloaded work‐loop contractions (b–h), bracketed by eight isometric contractions (a).
Mentions: Work‐loop contractions (Fig. 4), simplified versions of the contraction patterns of the heart, allow quantification of shortening‐related parameters (Fig. 5) and stress‐length work output (Figs. 4C, 7A). Coupled with simultaneous measurement of heat production (Figs. 4D, 6), work‐loop contractions allow quantification of enthalpy output (the sum of work and heat; Fig. 6) and hence mechanical efficiency (the ratio of work to enthalpy output; Fig. 7B and C).

Bottom Line: Our results show that, whereas the performance of the SHR-F differed little from that of the SHR-NF, both SHR groups performed less stress-length work than that of Wistar trabeculae.Their lower work output arose from reduced ability to produce sufficient force and shortening.Consequently, mechanical efficiency (the ratio of work to change of enthalpy) of both SHR groups was lower than that of the Wistar trabeculae.

View Article: PubMed Central - PubMed

Affiliation: Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.

No MeSH data available.


Related in: MedlinePlus