ISSN:
1432-1076
Keywords:
β-adrenoceptors
;
Down-regulation
;
Catecholamines
;
Congenital heart disease
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Twenty-six infants and children with congenital heart disease (CHD) undergoing cardiac surgery were investigated for alterations in myocardial β-adrenoceptor density. The patients were divided into three groups according to type and severity of CHD: group I consisted of 6 patients with acyanotic shunt lesions of moderate severity; group II comprised 13 children with severe acyanotic shunt and valve lesions and group III included 7 children with cyanotic CHD. The myocardial β-adrenoceptor density was determined using (−)3-[125I] Iodocyanopindolol ([125I]ICYP) and was reduced by approximately 50% in severe acyanotic CHD (33.6 fmol/mg protein) and cyanotic CHD (35.3 fmol/mg protein) in comparison with the group with less severe acyanotic shunt defects (64.4 fmol/mg protein). The affinity dissociation constant (K d, ICYP) did not differ statistically between the groups. The proportion of β1- and β1-subpopulation was evaluated by ICI 118,551-[125I]ICYP competition studies. In group II (61.5%) and group III (69.1%) significant lower portions of β1-adrenoceptors were found compared with group I (78.2%). This shift of subpopulations was due to a decreased β1-receptor density while β2-receptor density was unchanged in all groups. While the plasma noradrenaline levels of group I were similar to those of a control group of 13 healthy children, respective values of group II and III were significantly elevated. A significant negative correlation was found between plasma noradrenaline levels and myocardial β-adrenoceptor density. It is concluded that exposure of these receptors to increased circulating catecholamines, due to an enhanced sympathetic tone, leads to a reduction of their density. Noradrenaline, a preferential agonist of β1-adrenoceptors, is most probably responsible for the shift of the β-adrenoceptor subpopulations from the β1- to β2-subtype, depending on severity and type of cardiac disease.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02093715
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