title: Temperature and species-specific effects on ß3-adrenergic receptor cardiac regulation in two freshwater teleosts: Channel catfish (Ictalurus punctatus) and common carp (Cyprinus carpio).
abstract: β₃-adrenergic receptors (AR) are important in teleost cardiovascular regulation. To date, it is unknown whether temperature acclimation changes ß₃-AR functionality and consequently the involvement of this AR subtype in teleost cardiac regulation. Common carp (Cyprinus carpio) were acclimated at 12 °C or 23 °C (minimum 3 weeks) after which cardiovascular variables (cardiac output (Q), stroke volume (Sv) and heart rate (fH)) were measured upon injection of the ß₃-AR agonist, BRL(37344), and antagonist, SR(59230A). In both 12 °C and 23 °C acclimated carp, BRL(37344) induced significant increases in fH and Q whereas Sv was significantly decreased. While temperature did not affect the change (increase vs. decrease) in cardiac variables, the magnitude and on-set of responses differed. For instance, fH, Sv and Q responded significantly faster to ß₃-AR stimulation in 23 °C carp. In contrast, maximum responses of fH and Q were significantly higher in 23 °C carp whereas the maximum response of Sv was significantly greater in 12 °C carp. These findings suggest that temperature acclimation induced changes in β₃-AR receptor functionality (e.g. density and/or affinity). Stimulation of β₃-ARs in 23 °C acclimated channel catfish (Ictalurus punctatus) caused significant increases in fH, Sv and Q. The increase in Sv was opposite to the decrease observed in 23 °C acclimated common carp. SR(59230A) induced significant decreases in Sv and Q but had no effect in carp (23 °C). Results suggest species diversity in the density and affinity or structure of ß₃-ARs which may explain the different cardiac responses to ß₃-AR ligands.
authors.affiliation: University of North Texas, Department of Biology, Institute of Applied Science, 1155 Union Circle, P.O. Box 310559, Denton, TX 76203, United States. Electronic address: lene.petersen@unt.edu.
authors.forename: L H
authors.initials: LH
authors.lastname: Petersen
authors.affiliation: University of North Texas, Department of Biology, Institute of Applied Science, 1155 Union Circle, P.O. Box 310559, Denton, TX 76203, United States.
authors.forename: M L
authors.initials: ML
authors.lastname: Burleson
authors.affiliation: University of North Texas, Department of Biology, Institute of Applied Science, 1155 Union Circle, P.O. Box 310559, Denton, TX 76203, United States.
authors.forename: D B
authors.initials: DB
authors.lastname: Huggett
mesh_terms: D000064:Acclimatization; D000818:Animals; D002302:Cardiac Output; D002347:Carps / Q000378:metabolism*; D029941:Fish Proteins / Q000502:physiology*; D006339:Heart Rate; D007059:Ictaluridae / Q000378:metabolism*; D022702:Receptors, Adrenergic, beta-3 / Q000502:physiology*; D056152:Respiratory Rate; D013045:Species Specificity; D013318:Stroke Volume; D013696:Temperature
chemical_list: D029941:Fish Proteins; D022702:Receptors, Adrenergic, beta-3
keywords: Cardiac output; Catecholamines; Teleosts; Temperature; β(3)-adrenergic receptors