title: Reduced beta 1 receptor messenger RNA abundance in the failing human heart.
abstract: Heart failure in humans is characterized by alterations in myocardial adrenergic signal transduction, the most prominent of which is down-regulation of beta 1-adrenergic receptors. We tested the hypothesis that down-regulation of beta 1-adrenergic receptors in the failing human heart is related to decreased steady-state levels of beta 1 receptor mRNA. Due to the extremely low abundance of beta 1 receptor mRNA, measurements were possible only by quantitative polymerase chain reaction (QPCR) or by RNase protection methods. Because the beta 1 receptor gene is intronless and beta 1 receptor mRNA abundance is low, QPCR yielded genomic amplification in total RNA, and mRNA measurements had to be performed in poly (A)(+)-enriched RNA. By QPCR the concentration of beta 1 receptor mRNA varied from 0.34 to 7.8 x 10(7) molecules/microgram poly(A)(+)-enriched RNA, and the assay was sensitive to 16.7 zeptomol. Using 100-mg aliquots of left ventricular myocardium obtained from organ donors (nonfailing ventricles, n = 12) or heart transplant recipients (failing ventricles, n = 13), the respective beta 1 mRNA levels measured by QPCR were 4.2 +/- 0.7 x 10(7)/micrograms vs. 2.10 +/- 0.3 x 10(7)/micrograms (P = 0.006). In these same nonfailing and failing left ventricles the respective beta 1-adrenergic receptor densities were 67.9 +/- 6.9 fmol/mg vs. 29.6 +/- 3.5 fmol/mg (P = 0.0001). Decreased mRNA abundance in the failing ventricles was confirmed by RNase protection assays in total RNA, which also demonstrated a 50% reduction in beta 1 message abundance. We conclude that down-regulation of beta 1 receptor mRNA contributes to down-regulation of beta 1 adrenergic receptors in the failing human heart.
authors.affiliation: Temple Hoyne Buell Laboratories, Division of Cardiology, University of Colorado Health Sciences Center, Denver 80262.
authors.forename: M R
authors.initials: MR
authors.lastname: Bristow
authors.forename: W A
authors.initials: WA
authors.lastname: Minobe
authors.forename: M V
authors.initials: MV
authors.lastname: Raynolds
authors.forename: J D
authors.initials: JD
authors.lastname: Port
authors.forename: R
authors.initials: R
authors.lastname: Rasmussen
authors.forename: P E
authors.initials: PE
authors.lastname: Ray
authors.forename: A M
authors.initials: AM
authors.lastname: Feldman
mesh_terms: D016375:Antisense Elements (Genetics); D001483:Base Sequence; D004247:DNA / Q000302:isolation & purification / Q000378:metabolism; D017931:DNA Primers; D006333:Heart Failure / Q000378:metabolism* / Q000601:surgery; D016027:Heart Transplantation; D016041:Heart-Lung Transplantation; D006801:Humans; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D018342:Receptors, Adrenergic, beta-1 / Q000096:biosynthesis*; D018343:Receptors, Adrenergic, beta-2 / Q000096:biosynthesis; D012016:Reference Values
chemical_list: D016375:Antisense Elements (Genetics); D017931:DNA Primers; D012333:RNA, Messenger; D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; D004247:DNA