title: Cocaine- and amphetamine-regulated transcript (CART) peptide as an in vivo regulator of cardiac function in Rana ridibunda frog.
abstract: The aim of this study was to investigate the effect of CART peptide on cardiac performance and on the physiological signalling pathways involved using Rana ridibunda frog heart preparations in vivo. The CART peptide, when injected into the venous sinus, significantly and reproducibly increased the force of frog heart contractions by up to 33.0 +/- 6.4% during the first 15 min after its application but did not influence the chronotropic activity of the frog heart. The positive inotropic effect was entirely blocked by prazosin, pertussis toxin, R(p)-adenosine 3',5'-cyclic monophosphorothioate, autosauvagine 30 or metyrapone, as well as by extirpation of the pituitary gland, functional elimination of the inter-renal glands and long-lasting starvation, and was not observed on isolated heart preparations. Propranolol and double pithing were without significant effect on this phenomenon. It was concluded that: (i) CART peptide, administered to frogs in vivo, increases the force of heart contractions; (ii) this effect of the peptide is exerted via activation of the hypothalamic-pituitary-inter-renal gland axis through a corticoliberin-sensitive mechanism; (iii) CART augments the pumping function of the heart via a corticosteroid-dependent potentiation of myocardial alpha(1)-adrenoreceptors signalling; and (iv) prolonged food deprivation abolishes the positive inotropic effect of CART, suggesting the participation of endogenous CART in the physiological adaptation of the circulatory system to limitations of energy consumption.
authors.affiliation: Faculty of Biology, University of Sofia St Kliment Ohridski, 1164 Sofia, Bulgaria.
authors.forename: Iliyana V
authors.initials: IV
authors.lastname: Ivanova
authors.forename: Rudolf
authors.initials: R
authors.lastname: Schubert
authors.forename: Dessislava B
authors.initials: DB
authors.lastname: Duridanova
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Bolton
authors.forename: Lubomir T
authors.initials: LT
authors.lastname: Lubomirov
authors.forename: Hristo S
authors.initials: HS
authors.lastname: Gagov
mesh_terms: D000818:Animals; D005508:Food Deprivation / Q000502:physiology; D006321:Heart / Q000502:physiology*; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D023421:Models, Animal; D009200:Myocardial Contraction / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000502:physiology*; D011895:Rana ridibunda; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
chemical_list: D009419:Nerve Tissue Proteins; D018340:Receptors, Adrenergic, alpha-1; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein