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Are developing beta-adrenoceptors able to desensitize? Acute and chronic effects of beta-agonists in neonatal heart and liver.

Publication ,  Journal Article
Auman, JT; Seidler, FJ; Tate, CA; Slotkin, TA
Published in: Am J Physiol Regul Integr Comp Physiol
July 2002

During fetal and neonatal development, beta-adrenergic receptors (beta-ARs) appear to be resistant to desensitization by beta-agonist drugs. To determine the mechanisms underlying the regulatory differences between adults and neonates, we administered isoproterenol, a mixed beta(1)/beta(2)-AR agonist, and terbutaline, a beta(2)-selective agonist. Effects were examined in the ensuing 4 h after a single injection, or after the last of four daily injections. We prepared cell membranes from heart (predominantly beta(1)-ARs) and liver (predominantly beta(2)-ARs) and assessed signal transduction in the adenylyl cyclase (AC) pathway. In the first few hours after a single administration of isoproterenol to adult rats, cardiac beta-ARs showed activation of G proteins (elevated AC response to forskolin) and desensitization of beta-AR-mediated responses; after the fourth injection, heterologous desensitization emerged, characterized by a loss of signaling mediated either through beta-ARs or glucagon receptors. Terbutaline evoked an increase in the forskolin response but no desensitization of receptor-mediated responses. When we gave the same treatments to neonatal rats, we observed cardiac G protein activation, but there was neither homologous nor heterologous desensitization of beta-ARs or glucagon receptors. In the adult liver, isoproterenol and terbutaline both failed to evoke desensitization, regardless of whether the drugs were given once or for 4 days. In neonates, however, acute or chronic treatment elicited homologous desensitization of beta-AR-mediated AC signaling, while sensitizing the response to glucagon. These results show that neonatal beta-ARs are inherently capable of desensitization in some, but not all, cell types; cellular responses can be maintained through heterologous sensitization of signaling proteins downstream from the receptor. Differences from adult patterns of response are highly tissue selective and are likely to depend on ontogenetic differences in subtypes of beta-ARs and AC.

Duke Scholars

Published In

Am J Physiol Regul Integr Comp Physiol

DOI

ISSN

0363-6119

Publication Date

July 2002

Volume

283

Issue

1

Start / End Page

R205 / R217

Location

United States

Related Subject Headings

  • Time Factors
  • Terbutaline
  • Sex Characteristics
  • Receptors, Adrenergic, beta
  • Rats, Sprague-Dawley
  • Rats
  • Physiology
  • Myocardium
  • Male
  • Liver
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Auman, J. T., Seidler, F. J., Tate, C. A., & Slotkin, T. A. (2002). Are developing beta-adrenoceptors able to desensitize? Acute and chronic effects of beta-agonists in neonatal heart and liver. Am J Physiol Regul Integr Comp Physiol, 283(1), R205–R217. https://doi.org/10.1152/ajpregu.00122.2002
Auman, J. T., F. J. Seidler, C. A. Tate, and T. A. Slotkin. “Are developing beta-adrenoceptors able to desensitize? Acute and chronic effects of beta-agonists in neonatal heart and liver.Am J Physiol Regul Integr Comp Physiol 283, no. 1 (July 2002): R205–17. https://doi.org/10.1152/ajpregu.00122.2002.
Auman JT, Seidler FJ, Tate CA, Slotkin TA. Are developing beta-adrenoceptors able to desensitize? Acute and chronic effects of beta-agonists in neonatal heart and liver. Am J Physiol Regul Integr Comp Physiol. 2002 Jul;283(1):R205–17.
Auman, J. T., et al. “Are developing beta-adrenoceptors able to desensitize? Acute and chronic effects of beta-agonists in neonatal heart and liver.Am J Physiol Regul Integr Comp Physiol, vol. 283, no. 1, July 2002, pp. R205–17. Pubmed, doi:10.1152/ajpregu.00122.2002.
Auman JT, Seidler FJ, Tate CA, Slotkin TA. Are developing beta-adrenoceptors able to desensitize? Acute and chronic effects of beta-agonists in neonatal heart and liver. Am J Physiol Regul Integr Comp Physiol. 2002 Jul;283(1):R205–R217.

Published In

Am J Physiol Regul Integr Comp Physiol

DOI

ISSN

0363-6119

Publication Date

July 2002

Volume

283

Issue

1

Start / End Page

R205 / R217

Location

United States

Related Subject Headings

  • Time Factors
  • Terbutaline
  • Sex Characteristics
  • Receptors, Adrenergic, beta
  • Rats, Sprague-Dawley
  • Rats
  • Physiology
  • Myocardium
  • Male
  • Liver