Institute of Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 15, D-04103 Leipzig, Germany.
Rudolf-Boehm-Institute of Pharmacology and Toxicology, Clinical Pharmacology, Faculty of Medicine, University of Leipzig, Härtelstr. 16 -18, D-04107 Leipzig, Germany.
Res Vet Sci. 2021 May;136:602-608. doi: 10.1016/j.rvsc.2021.04.016. Epub 2021 Apr 16.
The aim of the present study was to characterize the specific binding sites for [N-methyl-H]-scopolamine ([H]-NMS), a radioligand for labeling muscarinic acetylcholine receptors (mAChRs), in membranes of four heart chambers obtained from adult male British United Turkey (BUT) Big 6 ("meat-type") and Cröllwitzer ("wild-type") turkeys. MAChR subtypes were examined by inhibiting [H]-NMS binding with subtype selective non-labelled receptor antagonists. In all left and right atria as well as left and right ventricles of both turkey breeds, the specific [H]-NMS binding was saturable, reversible and of high affinity (K range: 0.5-1.0 nM). The maximum receptor density (B) was not significantly different between the four cardiac chambers of BUT Big 6 turkeys, but a significant difference was found between atria and ventricles of Cröllwitzer turkeys. Moreover, significant lower B was found in the atria of Cröllwitzer turkeys than in the atria of BUT Big 6, while the ventricular B was significantly higher. In all cardiac chambers, unlabeled mAChR antagonists competed for specific [H]-NMS binding sites in a concentration-dependent manner, suggesting the presence of the M and M receptor subtypes, whereby the latter was the predominant subtype. The presence of the M subtype could not be excluded. In conclusion, there was a difference between BUT Big 6 ("meat-type") and Cröllwitzer ("wild-type") turkeys with regard to receptor density in heart chambers with dominant M and M receptor subtypes.
本研究的目的是描述从成年雄性英国联合火鸡（BUT）Big 6（“肉用型”）和 Cröllwitzer（“野生型”）火鸡的四个心腔室获得的膜中用于标记毒蕈碱乙酰胆碱受体（mAChR）的 [N-甲基-H]-东莨菪碱（[H]-NMS）的特异性结合位点。mAChR 亚型通过用亚型选择性非标记受体拮抗剂抑制 [H]-NMS 结合来检查。在 BUT Big 6 火鸡的所有左右心房以及左右心室中，特异性 [H]-NMS 结合是可饱和的、可逆转的且具有高亲和力（K 范围：0.5-1.0 nM）。BUT Big 6 火鸡的四个心腔室之间的最大受体密度（B）没有显着差异，但在 Cröllwitzer 火鸡的心房和心室之间发现了显着差异。此外，在 Cröllwitzer 火鸡的心房中发现 B 显着低于 BUT Big 6 的心房，而心室 B 显着更高。在所有心腔室中，非标记的 mAChR 拮抗剂以浓度依赖性方式竞争特异性 [H]-NMS 结合位点，表明存在 M 和 M 受体亚型，其中后者是主要亚型。不能排除 M 亚型的存在。总之，BUT Big 6（“肉用型”）和 Cröllwitzer（“野生型”）火鸡在心腔室中存在受体密度的差异，主要存在 M 和 M 受体亚型。
