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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

Shortening kinetics obtained from work‐loop contractions. (A) Maximal extent of shortening (calculated from the end‐systolic length in Fig. 4C), (B) maximal velocity of shortening (at the times indicated by the circles in Fig. 4B), and (C) maximal power of shortening (calculated as the product of maximal velocity of shortening and active afterload, where active afterload is afterload minus peak passive stress), as functions of relative active afterload. *P < 0.05 for Wistar versus both spontaneously hypertensive rat (SHR) groups, +P < 0.05 for failing SHR (SHR‐F) versus nonfailing SHR (SHR‐NF). Peak values (mean ± SE) of variables were superimposed on appropriate panels as an indication of the variability of each average regression line. Note that the greatest SE occurred at peak values. The insets show data from a representative SHR‐F trabecula.
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fig05: Shortening kinetics obtained from work‐loop contractions. (A) Maximal extent of shortening (calculated from the end‐systolic length in Fig. 4C), (B) maximal velocity of shortening (at the times indicated by the circles in Fig. 4B), and (C) maximal power of shortening (calculated as the product of maximal velocity of shortening and active afterload, where active afterload is afterload minus peak passive stress), as functions of relative active afterload. *P < 0.05 for Wistar versus both spontaneously hypertensive rat (SHR) groups, +P < 0.05 for failing SHR (SHR‐F) versus nonfailing SHR (SHR‐NF). Peak values (mean ± SE) of variables were superimposed on appropriate panels as an indication of the variability of each average regression line. Note that the greatest SE occurred at peak values. The insets show data from a representative SHR‐F trabecula.

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)

Shortening kinetics obtained from work‐loop contractions. (A) Maximal extent of shortening (calculated from the end‐systolic length in Fig. 4C), (B) maximal velocity of shortening (at the times indicated by the circles in Fig. 4B), and (C) maximal power of shortening (calculated as the product of maximal velocity of shortening and active afterload, where active afterload is afterload minus peak passive stress), as functions of relative active afterload. *P < 0.05 for Wistar versus both spontaneously hypertensive rat (SHR) groups, +P < 0.05 for failing SHR (SHR‐F) versus nonfailing SHR (SHR‐NF). Peak values (mean ± SE) of variables were superimposed on appropriate panels as an indication of the variability of each average regression line. Note that the greatest SE occurred at peak values. The insets show data from a representative SHR‐F trabecula.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig05: Shortening kinetics obtained from work‐loop contractions. (A) Maximal extent of shortening (calculated from the end‐systolic length in Fig. 4C), (B) maximal velocity of shortening (at the times indicated by the circles in Fig. 4B), and (C) maximal power of shortening (calculated as the product of maximal velocity of shortening and active afterload, where active afterload is afterload minus peak passive stress), as functions of relative active afterload. *P < 0.05 for Wistar versus both spontaneously hypertensive rat (SHR) groups, +P < 0.05 for failing SHR (SHR‐F) versus nonfailing SHR (SHR‐NF). Peak values (mean ± SE) of variables were superimposed on appropriate panels as an indication of the variability of each average regression line. Note that the greatest SE occurred at peak values. The insets show data from a representative SHR‐F trabecula.
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