Biomedical subjects

G Doell

Publications and source records attributed to G Doell.

2 recordsLinked to original sources

PubMed1983

Radiation inactivation of alpha 1-adrenoceptors.

Radiation inactivation of alpha 1-adrenoceptors in rat cerebral cortex membranes has been performed with 10 MeV electrons from a linear accelerator at temperatures less than or equal to -100 degrees C. Alpha 1-adrenoceptor inactivation was monitored with [ 3H ]-prazosin and [( 125I ]-2-(beta-4-hydroxylphenyl)ethylaminomethyl)tetralone [( 125I ]-HEAT). Saturation analysis of irradiated membranes with both ligands indicated that a decrease in alpha-adrenoceptor density occurred with increasing radiation dose. The dissociation constants of [ 3H ]-prazosin and [ 125I ]-HEAT were not markedly changed by the irradiation. Application of the target volume theory gave molecular weights of 91,500 +/- 1,700 (S.D.) (D37: 19,6 +/- 0.36 Mrad) with [ 125I ]-HEAT as ligand, and 77,000 +/- 18,000 (S.D.) (D37: 23.3 +/- 4.6 Mrad) with [ 3H ]-prazosin, respectively, when an empirical temperature correction factor of 2.8 was used. [ 3H ]-flunitrazepam-labelled benzodiazepine receptor target size was used as an internal control. The molecular weight of the alpha 1-adrenoceptors, corrected for this internal control, was 85,000 +/- 1.600 [( 125I ]-HEAT) and 71,500 +/- 17,000 [( 3H ]-prazosin).

Animals↗

PubMed1982

Ionic modulation of alpha-adrenoceptors.

Effects of cations and nucleotides on the in vivo binding properties of alpha-adrenoceptors in rat cerebral cortex membranes are described. Na+ ion converts a large fraction alpha-adrenoceptors in the absence or presence of Mg2+ into a low affinity state. The effects of 10 mM Na+ can be observed in 250 mM Tris-HCL buffer. It is suggested that alpha 2-adrenoceptor agonists alter the affinity of Na+ for a receptor-associated membrane component. alpha 2-Adrenoceptors are linked to guanylnucleotide binding proteins, which may be involved in signal transfer. These sites are altered in their nucleotide binding properties by pretreatment of the membranes with a medium that allows for ADP ribosylation or/and phosphorylation. alpha 1-Adrenoceptors were probed with a new, high affinity ligand, 125J-HEAT. 125J-HEAT binds (30 degrees C) with Kd values between 6 and 8 pM to alpha 1-adrenoceptors if Na+ slows down the dissociation of 125J-HEAT in comparison with MG2+. Na+ as well as Mg2+ reverse the inhibitory action of phosphatidic acid on the alpha 1-adrenoceptors labeled by 125J-HEAT. Data on the target size, obtained by radiation inactivation, of the alpha 1-adrenoceptors are presented.

Adrenergic alpha-Antagonists↗