Heart rate modulates the slow enhancement of contraction due to sudden left ventricular dilation

Heart rate modulates the slow enhancement of contraction due to sudden left ventricular dilation

Author Tucci, Paulo José Ferreira Autor UNIFESP Google Scholar
Murad, Neif Autor UNIFESP Google Scholar
Rossi, Clever Land Autor UNIFESP Google Scholar
Nogueira, Roberto Janzon Autor UNIFESP Google Scholar
Santana Junior, Orlando Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract In isovolumic blood-perfused dog hearts, left ventricular developed pressure (DP) was recorded while a sudden ventricular dilation was promoted at three heart rate (HR) levels: low (L: 52 +/- 1.7 beats/min), intermediate (M: 82 +/- 2.2 beats/min), and high (H: 117 +/- 3.5 beats/min). DP increased instantaneously with chamber expansion (Delta 1DP), and another continuous increase occurred for several minutes (Delta 2DP). HR elevation did not alter Delta 1DP (32.8 +/- 1.6, 33.6 +/- 1.5, and 34.3 +/- 1.2 mmHg for L, M, and H, respectively), even though it intensified Delta 2DP (17.3 +/- 0.9, 20.7 +/- 1.0, and 26.8 +/- 1.2 mmHg for L, M, and H, respectively), meaning that the treppe phenomenon enhances the length dependence of the contraction component related to changes in intracellular Ca2+ concentration. Frequency increments reduced the half time of the slow response (82 +/- 3.6, 67 +/- 2.6, and 53 +/- 2.0 s for L, M, and H, respectively), while the number of beats included in half time increased (72 +/- 2.9, 95 +/- 2.9, and 111 +/- 3.2 beats for L, M, and H, respectively). HR modulation of the slow response suggests that L-type Ca2+ channel currents and/or the Na+/Ca2+ exchanger plays a relevant role in the stretch-triggered Ca2+ gain when HR increases in the canine heart.
Keywords length-dependent activation
slow force response
Bowditch effect
intact canine heart
Language English
Date 2001-05-01
Published in American Journal Of Physiology-heart And Circulatory Physiology. Bethesda: Amer Physiological Soc, v. 280, n. 5, p. H2136-H2143, 2001.
ISSN 0363-6135 (Sherpa/Romeo, impact factor)
Publisher Amer Physiological Soc
Extent H2136-H2143
Origin http://ajpheart.physiology.org/content/280/5/H2136
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000168027600025
URI http://repositorio.unifesp.br/11600/42349

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