ISSN:
1432-1076
Keywords:
β-Adrenoceptor density
;
β-Adrenoceptor affinity
;
High and low receptor affinity state
;
B and T-cells
;
Asthmatic children
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract β-adrenoceptor binding in lymphocytes of asthmatic and non-asthmatic children and healthy adult volunteers was investigated with the radioligand 125-iodocyanopindolol (ICYP). Binding studies were performed with 4 to 5 different concentrations of ICYP. Receptor density and affinity were calculated by Scatchard plots. Resolution of β-adrenoceptors into those of high and low affinity state was obtained from inhibition curves with salbutamol using Hofstee plots. Receptor density in B-cell enriched fractions was two to three-fold higher than in T-cells for all patients and volunteers studied (P less than 0.025). No difference in β-adrenoceptor density on B and T-cells occurred neither in age-matched asthmatic and non-asthmatic children nor in adult volunteers. The affinity of β-adrenoceptors did not differ for B and T-cells nor for the patients or volunteers studied. However, when two distinct binding states for β-adrenoceptor agonists were obtained using salbutamol displacement curves it appeared that β-adrenoceptors on T-cells were at a higher affinity state compared to those on B-cells in asthmatic and non-asthmatic children, as well as in adults. Since the ability of an agonist to activate adenylate cyclase correlates closely with the amount of high affinity receptor state formed in the presence of the agonist, increased intrinsic activity of the β-adrenoceptor agonist on T-cells may be postulated. In conclusion, age-related control groups and determination of the B/T ratio are neccessary for interpretation of β-adrenoceptor changes in bronchial asthma.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00442206
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