Effect of chemical sympathectomy on (−)‐isoprenaline‐induced changes in cardiac β‐adrenoceptor subtypes in the guinea‐pig and rat

Abstract

1 Quantitative autoradiography was used to determine β‐adrenoceptor densities in cardiac regions of guinea‐pigs and rats after chemical sympathectomy with 6‐hydroxydopamine, and to examine how chemical sympathectomy affected β‐adrenoceptor changes following infusion of (‐)‐isoprenaline (400 μg kg−1 hr−1, 7 days). 2 Seven days after 6‐hydroxydopamine (100 mg kg−1, i.v.), cardiac tissue levels of noradrenaline were reduced by 94.0± 3.5% (guinea‐pig) and 86.0 ± 7.0% (rat). The blood pressure increase in rats to tyramine (0.5 mg, i.v.) was reduced from 118 mmHg in 6‐hydroxydopamine‐treated animals. 3 There were no changes 7 and 14 days after 6‐hydroxydopamine treatment in total, β1‐ and β2‐adren..