Acute depression of myocardial beta-adrenergic receptor signaling during cardiopulmonary bypass: impairment of the adenylyl cyclase moiety. Duke Heart Center Perioperative Desensitization Group.

Published

Journal Article

BACKGROUND: Previously the authors showed that myocardial beta-adrenergic (betaAR) function is reduced after cardiopulmonary bypass (CPB) in a canine model Whether CPB results in similar effects on betaAR function in adult humans is not known. Therefore the current study tested two hypotheses: (1) That myocardial betaAR signaling is reduced in adult humans after CPB, and (2) that administration of long-term preoperative betaAR antagonists prevents this process. METHODS: After they gave informed consent, 52 patients undergoing aortocoronary surgery were enrolled. Atrial biopsies were obtained before CPB and immediately before discontinuation of CPB. Plasma catecholamine concentrations, myocardial betaAR density, and functional responsiveness (basal, isoproterenol, zinterol, sodium fluoride, and manganese-stimulated adenylyl cyclase activity) were assessed. RESULTS: Catecholamine levels increased significantly during CPB (P < 0.005). Myocardial betaAR adenylyl cyclase coupling decreased during CPB, as evidenced by a 21% decrease in isoproterenol-stimulated adenylyl cyclase activity (750 [430] pmol cyclic adenosine monophosphate per milligram total protein 15 min before CPB compared with 540 [390] at the end of CPB, P = 0.0062, medians [interquartile range]) despite constant betaAR density. Differential activation along the betaAR signal transduction cascade localized the defect to the adenylyl cyclase moiety. Administration of long-term preoperative betaAR antagonists did not prevent acute CPB-induced myocardial betaAR dysfunction. CONCLUSIONS: These data indicate that the myocardial adenylyl cyclase response to betaAR agonists decreases acutely in adults during aortocoronary surgery requiring CPB, regardless of whether long-term preoperative betaAR antagonists are administered. The mechanism underlying acute betaAR dysfunction appears to be direct impairment of the adenylyl cyclase moiety. Similar increases in manganese-stimulated activity before and at the end of CPB show preserved adenylyl cyclase catalytic activity, suggesting that other mechanisms (such as decreased protein levels or altered isoform expression or function) may be responsible for decreased adenylyl cyclase function.

Full Text

Duke Authors

Cited Authors

  • Booth, JV; Landolfo, KP; Chesnut, LC; Bennett-Guerrero, E; Gerhardt, MA; Atwell, DM; El-Moalem, HE; Smith, MS; Funk, BL; Kuhn, CM; Kwatra, MM; Schwinn, DA

Published Date

  • September 1998

Published In

Volume / Issue

  • 89 / 3

Start / End Page

  • 602 - 611

PubMed ID

  • 9743395

Pubmed Central ID

  • 9743395

Electronic International Standard Serial Number (EISSN)

  • 1528-1175

International Standard Serial Number (ISSN)

  • 0003-3022

Digital Object Identifier (DOI)

  • 10.1097/00000542-199809000-00008

Language

  • eng