title: Effects of halothane, sevoflurane and desflurane on the force-frequency relation in the dog heart in vivo.
abstract: OBJECTIVE
  Frequency potentiation is the increase in force of contraction induced by an increased heart rate (HR). This positive staircase phenomenon has been attributed to changes in Ca2+ entry and loading of intracellular Ca2+ stores. Volatile anesthetics interfere with Ca2+ homeostasis of cardiomyocytes. We hypothesized that frequency potentiation is altered by volatile anesthetics and investigated the influence of halothane (H), sevoflurane (S) and desflurane (D) on the positive staircase phenomenon in dogsin vivo.
  
  
  METHODS
  Dogs were chronically instrumented for measurement of left ventricular (LV) pressure and cardiac output. Heart rate was increased by atrial pacing from 120 to 220 beats·min-1and the LV maximal rate of pressure increase (dP/ dtmax) was determined as an index of myocardial performance. Measurements were performed in conscious dogs and during anesthesia with 1.0 minimal alveolar concentrations of each of the three inhaled anesthetics.
  
  
  RESULTS
  Increasing HR from 120 to 220 beats·min-1increased dP/dtmaxfrom 3394 ± 786 (mean ± SD) to 3798 ± 810 mmHg sec-1 in conscious dogs. All anesthetics reduced dP/dtmaxduring baseline (at 120 beatss·min-1: H, 1745 ± 340 mmHgs·sec-1; S, 1882 ± 418; D, 1928 ± 454, allP < 0.05vs awake) but did not influence the frequency potentiation of dP/dtmax (at 220 beatss·min-1: H, 1981 ± 587 mmHgs·sec-1; S, 2187 ± 787; D, 2307 ± 691). The slope of the regression line correlating dP/dtmaxand HR was not different between awake and anesetized dogs. Increasing HR did not influence cardiac output in awake or anesthetized dogs.
  
  
  CONCLUSIONS
  These results indicate that volatile anesthetics do not alter the force-frequency relation in dogs in vivo.
authors: Department of Anesthesiology, Academic Medical Center, University of Amsterdam, The Netherlands. b.preckel@amc.uva.nl.|Department of Anesthesiology, University Hospital of Duesseldorf, Germany. b.preckel@amc.uva.nl.
authors: Benedikt
authors: B
authors: Preckel
authors: Department of Anesthesiology, University Hospital of Duesseldorf, Germany.|Department of Anesthesiology, University of Louisville, Louisville, Kentucky, USA.
authors: Detlef
authors: D
authors: Obal
authors: South Tyneside District Hospital, South Shields, UK.
authors: Jost
authors: J
authors: Möllenheim
authors: Institute for Physiology, University of Duesseldorf, Germany.
authors: Juliane
authors: J
authors: Hennes
authors: Institute for Physiology, University of Duesseldorf, Germany.
authors: Marc
authors: M
authors: Heiderhoff
authors: Institute for Physiology, University of Duesseldorf, Germany.
authors: Volker
authors: V
authors: Thämer
authors: Department of Anesthesiology, Academic Medical Center, University of Amsterdam, The Netherlands.|Department of Anesthesiology, University Hospital of Duesseldorf, Germany.
authors: Wolfgang
authors: W
authors: Schlack