2.2. Preparation of Drug-Containing Serum, Matrine, and Scopoletin

We purchased 32 male Sprague Dawley rats (6–8 weeks, 180–200 g) from Beijing Vital River Laboratory Animal Technology Co., Ltd (laboratory animal production license number: SCXK (Jing) 2016-0006). Ethical approval for the study was granted by the Ethics Committee of Hebei University of Chinese Medicine (Yxll2021040). The rats were kept in a clean animal room with 12-h dark and 12-h light. Rats were left freely to eat and drink. SD rats were randomly divided into four groups. Qinghao formula granules (20080261) were purchased from the National Medical Hall of Hebei University of traditional Chinese medicine. Qinghao formula granules were administered orally to Qinghao group rats (medicinal slices 2.7 g/kg). The size per gram of Qinghao formula granules was equal to 14.3 per gram of medicinal tablets. Similarly, we purchased Kushen formula granules (20082661) from the National Medical Hall of Hebei University of Traditional Chinese Medicine. Kushen formula granules were administered orally to Kushen group rats (medicinal slices 1.44 g/kg). The size per gram of Kushen formula granules was equal to 12 per gram of medicinal tablets. Qinghao and Kushen were administered orally to Qinghao-Kushen group rats. The same dose of normal saline was administered orally to blank serum group rats. Twice a day for 4 days, the rats were anesthetized with pentobarbital (100 mg/kg) 1 hour after the last administration. Blood was collected from the abdominal aorta in a sterile manner, which was then centrifuged and bathed at 56°C and finally filtered, packed, and stored at −80°C for further use. Matrine and scopoletin were purchased from MedChemExpress Co., Ltd (Monmouth Junction, NJ, USA) and dissolved these drugs with dimethyl sulfoxide (DMSO) (Sigma, Aldrich; Merck KGaA).