Decreased beta-adrenergic receptor density in mononuclear leukocytes from thyroidectomized patients

Abstract

Beta-adrenergic receptor characteristics were investigated in peripheral blood mononuclear leukocytes taken from patients before and after partial thyroidectomy. In order to discriminate the effect of surgical stress per se from that of thyroidectomy, the analysis was also performed on patients before and after cholecystectomy. Receptor characteristics were determined by using dihydroalprenolol as ligand in direct equilibrium binding experiments. The binding affinity showed no changes either when two different surgical treatments were compared or when the same patient was analysed before and after the operation. On the contrary, a significant decrease in receptor density was found in thyroidectomized patients when compared pre-and post-operatively. This fall in receptor number seems to be linked with thyroid function since no statistically significant changes were observed in cholecystectomized patients in relation to surgical operation. This view is further supported by data on T3 serum levels, which show a significant fall after thyroidectomy but no statistically significant modifications after cholecystectomy. It is concluded that betaadrenoceptor modulation plays an important role in the relationship between thyroid and beta-adrenergic system.Many clinical signs of hyperthyroidism are known to mimic the effects of beta-adrenergic stimulation. Manifestations such as increased myocardial con¬ tractility, tachycardia, hyperkinesis and diaphoresis

Acebutolol-Induced Decrease of Mononuclear Leukocyte β-Adrenoceptors in Hypertension

“…The same parallelism adds new support to the hypothesis that human MNL may be used as a tool to estimate receptor character istics of other human tissues which cannot be studied directly [8][9][10]15]. Present findings on the regulation of receptors by drugs with ISA may also be useful in the development of the pharmacological research strategics in this area.…”

“…The steady-state binding assay has been described previously [10], The most relevant points arc staled here. MNL.…”

“…The method has already been used in assays of P-adrenoceptors from either mouse subman dibular glands [13] or human MNL [8,10).…”

Atenolol-Induced Regulation of Leukocyte β₂-Adrenoceptors in Hypertension

“…The steady-state binding assay has been described in a previous paper [7], The most relevant points are given in the following. Mononuclear leukocytes (MNL), isolated from heparinized fresh blood, were resuspended in incubation buffer and frozen in liquid nitrogen.…”

“…Binding of DHA to both specific and non-specific sites was estimated by mathematical treatment of total (specific + non-specific) binding data, as previously described [9], The method has already been used in assays of P-adrenoceptors from either mouse subman dibular glands [10] or human lymphocytes [7], Esti mations of non-specific binding by both mathematical and conventional method give consistent results. In addition, the mathematical approach permits saving time and material and enables one to assess the accu racy of parameter calculation.…”