Takayanagi I, Koike K, Nakagoshi A
Can J Physiol Pharmacol. 1987 Jan;65(1):18-22. doi: 10.1139/y87-004.
Interactions of derivatives of befunolol (BFE-37, BFE-55, and BFE-61), carteolol, and pindolol with beta-adrenoceptors were tested in guinea pig isolated taenia caecum. All the drugs used acted as partial agonists on the beta-adrenoceptors when compared with isoprenaline, a full agonist. The pA2 values of BFE-61, carteolol, and pindolol were significantly larger than their pD2 values, while there was no significant difference between the pA2 and pD2 values for BFE-37 and BFE-55. The specific binding of [3H]befunolol to microsomal fractions from the guinea pig taenia caecum distinguished two binding sites, high affinity and low affinity sites. Both sites are considered to be bound by 50 nM of [3H]befunolol. Specific 3H binding was displaced by BFE-61, carteolol, and pindolol in a biphasic manner but in a monophasic manner by BFE-37 and BFE-55. Furthermore, [3H]befunolol binding was only partially displaced by BFE-55 but completely displaced by the other drugs used. These results, together with our previous findings, suggest that BFE-61, carteolol, and pindolol discriminate between the two affinity binding sites in the beta-adrenoceptors, which are not discriminated between by BFE-37, and further that BFE-55 may bind with only the high affinity site.
在豚鼠离体盲肠带中测试了倍他洛尔（BFE - 37、BFE - 55和BFE - 61）、卡替洛尔和吲哚洛尔的衍生物与β - 肾上腺素能受体的相互作用。与完全激动剂异丙肾上腺素相比，所有使用的药物在β - 肾上腺素能受体上均表现为部分激动剂。BFE - 61、卡替洛尔和吲哚洛尔的pA2值显著大于其pD2值，而BFE - 37和BFE - 55的pA2值和pD2值之间无显著差异。[3H]倍他洛尔与豚鼠盲肠带微粒体部分的特异性结合区分出两个结合位点，即高亲和力位点和低亲和力位点。两个位点均被50 nM的[3H]倍他洛尔结合。特异性3H结合被BFE - 61、卡替洛尔和吲哚洛尔以双相方式取代，但被BFE - 37和BFE - 55以单相方式取代。此外，[3H]倍他洛尔结合仅被BFE - 55部分取代，但被其他所用药物完全取代。这些结果，连同我们之前的发现，表明BFE - 61、卡替洛尔和吲哚洛尔能区分β - 肾上腺素能受体中的两个亲和力结合位点，而BFE - 37不能区分，并且进一步表明BFE - 55可能仅与高亲和力位点结合。
