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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

Work output and efficiency as functions of relative afterload. Average dependences of work (A) and mechanical efficiency (B) on relative 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). Note that peak mechanical efficiency occurred at relative afterloads (0.45) lower than that for peak work (0.52). 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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fig07: Work output and efficiency as functions of relative afterload. Average dependences of work (A) and mechanical efficiency (B) on relative 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). Note that peak mechanical efficiency occurred at relative afterloads (0.45) lower than that for peak work (0.52). 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)

Work output and efficiency as functions of relative afterload. Average dependences of work (A) and mechanical efficiency (B) on relative 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). Note that peak mechanical efficiency occurred at relative afterloads (0.45) lower than that for peak work (0.52). 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

fig07: Work output and efficiency as functions of relative afterload. Average dependences of work (A) and mechanical efficiency (B) on relative 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). Note that peak mechanical efficiency occurred at relative afterloads (0.45) lower than that for peak work (0.52). 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