Nakao K, Kato H, Takagi K
Jpn J Pharmacol. 1975 Feb;25(1):25-34. doi: 10.1254/jjp.25.25.
The effects of beta-adrenergic receptor blocking agents administered i.v. on the blood pressure in conscious spontaneously hypertensive rats (SHR), renal hypertensive rats (RHR) and normotensive Wistar strain rats (NR) were studied. dl-Propranolol and dl-YB-2, 1 mg/kg i.v., caused a sustained rise in blood pressure in SHR and RHR. The maximum response of each beta-blocking agent after phentolamine, 10 mg/kg i.v., in SHR and RHR was significantly larger than that in NR. The potency ratio for the hypertensive activities of the 1- and d-isomers of propranolol and YB-2 was similar to the ratio of their beta-blocking activities. The pressor effects of the beta-blocking agents after phentolamine were significantly inhibited by adrenalectomy, reserpinization and pretreatment with hexamethonium. The results suggest that the pressor effect of the beta-blocking agents may be due to their beta-blocking activities and the unmasking of alpha-receptor activities of the blood vessels. Furthermore, the greater pressor effect of the agents observed in hypertensive rats is attributed to a greater activity of the sympathetic nervous system in these rats as compared to normotensive rats.
研究了静脉注射β-肾上腺素能受体阻滞剂对清醒自发性高血压大鼠（SHR）、肾性高血压大鼠（RHR）和正常血压的Wistar品系大鼠（NR）血压的影响。静脉注射1mg/kg的dl-普萘洛尔和dl-YB-2可使SHR和RHR的血压持续升高。静脉注射10mg/kg酚妥拉明后，SHR和RHR中每种β受体阻滞剂的最大反应明显大于NR。普萘洛尔和YB-2的1-异构体和d-异构体的升压活性效价比与其β受体阻滞活性比相似。酚妥拉明处理后，β受体阻滞剂的升压作用可被肾上腺切除术、利血平化和六甲铵预处理显著抑制。结果表明，β受体阻滞剂的升压作用可能与其β受体阻滞活性以及血管α受体活性的暴露有关。此外，在高血压大鼠中观察到的药物升压作用更强，这归因于与正常血压大鼠相比，这些大鼠的交感神经系统活性更高。
