Beta 2-adrenoceptor selectivity in four series of beta-adrenoceptor agonists

We studied the effect of two catechol and two resorcinol series of beta-adrenoceptor agonists on isolated papillary (beta 1-adrenoceptors) and soleus (beta 2-adrenoceptors) muscles preparations from the guinea-pig. One of the catechol and one of the resorcinol series were substituted by branched alkyl groups on the amino nitrogen, and the other two series were substituted by cycloalkyl groups. It was found that: the catechol derivatives were more potent than their corresponding resorcinol derivatives on both the papillary and the soleus muscle preparations, the resorcinol derivatives were more selective for the soleus muscle than their corresponding catechol derivatives, the substitution on the amino nitrogen gave compounds that were highly selective for the soleus muscle, both in the catechol and the resorcinol series. Greatest selectivity was obtained with a tertiary butyl group. the branched alkyl substitution on the amino nitrogen favoured selectivity for the soleus muscle more than cycloalkyl substitution did.