Kuttan S C, Sim M K
Department of Pharmacology, Faculty of Medicine, National University of Singapore.
J Cardiovasc Pharmacol. 1993 Mar;21(3):371-5. doi: 10.1097/00005344-199303000-00004.
Development of desensitization to physiologic concentration of norepinephrine (NE 10(-9) M) and its effects on angiotensin II (AII) tachyphylaxis in the aortic rings of adult and aged normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were investigated. Aortic rings of all animals developed desensitization to 10(-9) M NE and tachyphylaxis to AII (10(-9)-10(-6) M). In normotensive WKY, the response to NE and AII was not affected by age, whereas in SHR desensitization to NE and tachyphylaxis to AII were significantly more marked in aged animals. The desensitization to 10(-9) M NE appeared to be homologous because this physiologic concentration of NA significantly attenuated tachyphylaxis to AII (for concentrations of 10(-8)-10(-6) M) in the aortic rings of both adult and aged WKY. Tachyphylaxis to AII was not affected by 10(-9) M NE in either adult or aged SHR, however. These data support our previous finding of similar attenuation of AII tachyphylaxis by NE in aortic rings of normotensive Sprague-Dawley rats, and indicate that absence of such attenuation in SHR; the latter finding could reflect a probable lesion in the interactive pathways of these two vasoconstrictors in hypertensive rats.
研究了成年和老年正常血压Wistar-Kyoto大鼠（WKY）和自发性高血压大鼠（SHR）主动脉环对生理浓度去甲肾上腺素（NE 10(-9) M）的脱敏作用及其对血管紧张素II（AII）快速耐受的影响。所有动物的主动脉环均对10(-9) M NE产生脱敏作用，并对AII（10(-9)-10(-6) M）产生快速耐受。在正常血压的WKY中，对NE和AII的反应不受年龄影响，而在SHR中，老年动物对NE的脱敏作用和对AII的快速耐受作用明显更显著。对10(-9) M NE的脱敏作用似乎是同源性的，因为这种生理浓度的去甲肾上腺素显著减弱了成年和老年WKY主动脉环对AII（浓度为10(-8)-10(-6) M）的快速耐受。然而，在成年或老年SHR中，10(-9) M NE对AII的快速耐受没有影响。这些数据支持了我们之前在正常血压Sprague-Dawley大鼠主动脉环中发现的NE对AII快速耐受的类似减弱作用，并表明SHR中不存在这种减弱作用；后一发现可能反映了高血压大鼠中这两种血管收缩剂相互作用途径中可能存在的病变。
