RELEVANCE OF CHANGES IN ADRENOCEPTOR CHARACTERISTICS AFTER TERBUTALINE TREATMENT

  • 1 January 1983
    • journal article
    • research article
    • Vol. 50  (2) , 121-125
Abstract
Rats were treated with terbutaline in order to specify the in vivo [rat] effects of .beta.2-sympathicomimetic treatment in relation with desensitization phenomena on the level of pulmonary adrenoceptors. Maximal binding of 3H-dihydroalprenolol (3H-DHA) to lung membrane preparations, binding affinity and the relative amount of .beta.2-adrenoceptors were used as parameters. These were established 1, 3 and 6 days after a 10 day terbutaline treatment and compared with control values. Ten day treatment did not cause significant changes in the parameters measured. Maximal binding was enhanced 3 and 6 days after the last treatment, binding affinity was enhanced 3 and 6 days after the last treatment, while the relative amount of .beta.2-adrenoceptors was diminished 1 and 6 days after termination of the treatment. When the amount of .beta.2-adrenoceptors was calculated in terms of 3H-DHA binding, an increase could be shown 3 days after the last terbutaline treatment. The direct influence of the treatment on the .beta.-adrenoceptor population appeared to be small, dependent on the parameter used and probably not eliciting a functional desensitization.

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