Subtypes of α1-adrenoceptors in hippocampus of pigs, guinea-pigs, calves and humans: regional differences

Abstract

Radioligand binding studies were performed with membranes of guinea-pig, pig, calf and human hippocampus using [125I]BE 2254 (also known as [125I]HEAT) as the radioligand. [125I]BE 2254 bound with similar high affinity to saturable populations of recognition sites in all four membrane preparations. Competition curves obtained with a variety of ligangs (e.g., WB 4101, benoxathian, 5-methyl-urapidil) were biphasic and the profiles of the high- and low-affinity components of [125I]BE 2254 binding were similar in all four membrane preparations. The data suggest that [125I]BE 2254 labels two subtypes of α1-adrenoceptors in the hippocampus of these species. [3H]WB 4101 was used to label α1A recogn..