title: Dynamic changes in scope for heart rate and cardiac autonomic control during warm acclimation in rainbow trout.
abstract: Time course studies are critical for understanding regulatory mechanisms and temporal constraints in ectothermic animals acclimating to warmer temperatures. Therefore, we investigated the dynamics of heart rate and its neuro-humoral control in rainbow trout ( ITALIC! Onchorhynchus mykissL.) acclimating to 16°C for 39 days after being acutely warmed from 9°C. Resting heart rate was 39 beats min(-1)at 9°C, and increased significantly when fish were acutely warmed to 16°C ( ITALIC! Q10=1.9), but then declined during acclimation ( ITALIC! Q10=1.2 at day 39), mainly due to increased cholinergic inhibition while the intrinsic heart rate and adrenergic tone were little affected. Maximum heart rate also increased with warming, although a partial modest decrease occurred during the acclimation period. Consequently, heart rate scope exhibited a complex pattern with an initial increase with acute warming, followed by a steep decline and then a subsequent increase, which was primarily explained by cholinergic inhibition of resting heart rate.
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg SE-405 30, Sweden andreas.ekstrom@bioenv.gu.se.
authors.forename: Andreas
authors.initials: A
authors.lastname: Ekström
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg SE-405 30, Sweden.
authors.forename: Kim
authors.initials: K
authors.lastname: Hellgren
authors.affiliation: Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara SE-532 23, Sweden.
authors.forename: Albin
authors.initials: A
authors.lastname: Gräns
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg SE-405 30, Sweden.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Pichaud
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg SE-405 30, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Sandblom
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology*; D005260:Female; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006358:Hot Temperature; D008297:Male; D017686:Oncorhynchus mykiss / Q000502:physiology*
keywords: Acclimation dynamics; Cholinergic tone; Heart rate scope; Intrinsic heart rate; Maximum heart rate; Time course