The effect of reserpine, desipramine and thyroid hormone on alpha 1a- and alpha 1b-adrenoceptor binding sites: evidence for a subtype-specific regulation.

Using radioligand binding techniques we studied whether alpha 1a- and alpha 1b-adrenoceptor recognition sites can be regulated independently by drugs and hormones. In rat cerebral cortex subchronic treatment with reserpine enhanced the number of [3H]-prazosin binding sites and the proportion of alpha 1b binding sites. Desipramine treatment which did not alter Bmax values, increased the proportion of alpha 1a and decreased alpha 1b binding sites. In rat myocardium hypothyroidism decreased alpha 1b-adrenoceptor binding sites. These results suggest that alpha 1-adrenoceptors are regulated in a subtype-selective manner.