评估高亲和力 [F]氟吡啶坎地沙坦在大鼠肾 AT 受体 PET 成像中的应用。

Evaluation of the high affinity [F]fluoropyridine-candesartan in rats for PET imaging of renal AT receptors.

机构信息

Centre de recherche du Centre hospitalier de l'Université de Montréal, Montréal, Québec, Canada; Département de pharmacologie et physiologie, Faculté de médecine, Université de Montréal, Montréal, Québec, Canada; Institute de génie biomédical, Faculté de médecine, Université de Montréal, Montréal, Québec, Canada; Departamento de Radioquímica, Instituto Superior de Tecnologías y Ciencias Aplicadas, Universidad de la Habana, La Habana, Cuba.

出版信息

Nucl Med Biol. 2021 May-Jun;96-97:41-49. doi: 10.1016/j.nucmedbio.2021.03.003. Epub 2021 Mar 22.

DOI:10.1016/j.nucmedbio.2021.03.003

PMID:33798796

Abstract

INTRODUCTION

Alterations in the expression of the Angiotensin II type 1 receptors (ATR) have been demonstrated in the development of several heart and renal diseases. The aim of this study was to evaluate the novel compound [F]fluoropyridine-candesartan as a PET imaging tracer of ATR in rat kidneys.

METHODS

Competition binding assays were carried out with membranes from CHO-K1 cells expressing human ATR. Binding to plasma proteins was assessed by ultrafiltration. Radiolabeled metabolites in rat plasma and kidneys of control and pretreated animals (candesartan 10 mg/kg or losartan 30 mg/kg) were analyzed by column-switch HPLC. Dynamic PET/CT images of [F]fluoropyridine-candesartan in male Sprague-Dawley rats were acquired for 60 min at baseline, pre-treatment with the ATR antagonist losartan (30 mg/kg) or the ATR antagonist PD123,319 (5 mg/kg).

RESULTS

Fluoropyridine-candesartan bound with a high affinity for ATR (Ki = 5.9 ± 1.1 nM), comparable to fluoropyridine-losartan but lower than the parent compound candesartan (Ki = 0.4 ± 0.1 nM). [F]Fluoropyridine-candesartan bound strongly to plasma proteins (99.3%) and was mainly metabolized to radiolabeled hydrophilic compounds, displaying minimal interference on renal ATR binding with 82% of unchanged tracer in the kidneys at 20 min post-injection. PET imaging displayed high renal and liver accumulations and slow clearances, with maximum tissue-to-blood ratios of 14 ± 3 and 54 ± 12 in kidney cortex and liver, respectively, at 10 min post-injection. Binding specificity for ATR was demonstrated with marked reductions in kidney cortex (-84%) and liver (-93%) tissue-to-blood ratios at 20 min post-injection, when blocking with ATR antagonist losartan (30 mg/kg). No change was observed in kidney cortex of rats pre-treated with ATR antagonist PD 123,319 (5 mg/kg), confirming binding selectivity for AT over AT receptors.

CONCLUSION

High kidney-to-blood ratios and binding selectivity to renal ATR combined with tracer in vivo stability displaying minimal interference from labeled metabolites support further PET imaging studies with [F]fluoropyridine-candesartan.

摘要

简介

血管紧张素 II 型 1 型受体（ATR）的表达改变已在多种心脏和肾脏疾病的发展中得到证实。本研究旨在评估新型化合物[F]氟吡啶坎地沙坦作为大鼠肾脏中 ATR 的 PET 成像示踪剂。

方法

用表达人 ATR 的 CHO-K1 细胞的膜进行竞争结合测定。通过超滤评估与血浆蛋白的结合。用柱切换 HPLC 分析对照和预处理动物（坎地沙坦 10mg/kg 或氯沙坦 30mg/kg）的大鼠血浆和肾脏中放射性标记的代谢物。在基线时、用 ATR 拮抗剂氯沙坦（30mg/kg）或 ATR 拮抗剂 PD123,319（5mg/kg）预处理后，对雄性 Sprague-Dawley 大鼠进行[F]氟吡啶坎地沙坦的动态 PET/CT 成像，采集 60 分钟。

结果

氟吡啶坎地沙坦与 ATR 具有高亲和力（Ki = 5.9 ± 1.1 nM），与氟吡啶氯沙坦相当，但低于母体化合物坎地沙坦（Ki = 0.4 ± 0.1 nM）。[F]氟吡啶坎地沙坦与血浆蛋白结合牢固（99.3%），主要代谢为放射性标记的亲水性化合物，在注射后 20 分钟时，肾脏中未改变示踪剂的比例为 82%，对肾脏 ATR 结合的干扰最小。PET 成像显示肾脏和肝脏的摄取量高，清除速度慢，注射后 10 分钟时，肾脏皮质和肝脏的组织与血液的最大比值分别为 14 ± 3 和 54 ± 12。用 ATR 拮抗剂氯沙坦（30mg/kg）阻断后，肾脏皮质（-84%）和肝脏（-93%）组织与血液的比值明显降低，证明了对 ATR 的结合特异性。预先用 ATR 拮抗剂 PD123,319（5mg/kg）处理的大鼠肾脏皮质未见变化，证实了对 AT1 受体的结合选择性。