Hamilton C A, Howie C A, Reid J L
University Department of Materia Medica, Stobhill General Hospital, Glasgow, UK.
J Hypertens. 1988 Apr;6(4):277-82.
The effects of infusion of alpha-adrenoceptor agonists on blood pressure, pressor responses to bolus doses of agonists and to platelet aggregation were examined in rabbits with perinephritis hypertension and in sham-operated controls. Pressor responses to bolus doses and infusions of phenylephrine, an alpha 1-selective agonist, were greater in hypertensive rabbits. In contrast, responses to boluses but not infusions of alpha-methylnoradrenaline, a selective alpha 2-agonist, were increased in hypertensives. During alpha-methylnoradrenaline infusions pressor responses to bolus doses of alpha-methylnoradrenaline and the aggregatory response of platelets to adrenaline were attenuated in all rabbits, consistent with alpha 2-adrenoceptor desensitization. Attenuation and recovery were observed within minutes of commencing and ceasing infusion. The extent of attenuation and rate of change were generally increased in hypertensive animals. This could explain the apparent increase in pressor responses to bolus doses but not infusions of alpha-methylnoradrenaline in the hypertensive rabbits. It might also contribute to the lability in blood pressure observed in these animals.
在患有肾周炎高血压的兔子和假手术对照组中，研究了输注α-肾上腺素能受体激动剂对血压、对单次推注激动剂的升压反应以及血小板聚集的影响。高血压兔子对单次推注和输注α1选择性激动剂去氧肾上腺素的升压反应更大。相比之下，高血压兔子对单次推注选择性α2激动剂α-甲基去甲肾上腺素的反应增加，但对其输注的反应未增加。在输注α-甲基去甲肾上腺素期间，所有兔子对单次推注α-甲基去甲肾上腺素的升压反应以及血小板对肾上腺素的聚集反应均减弱，这与α2肾上腺素能受体脱敏一致。在开始和停止输注的几分钟内观察到了减弱和恢复。高血压动物的减弱程度和变化率通常增加。这可以解释高血压兔子对单次推注α-甲基去甲肾上腺素而非其输注的升压反应明显增加的现象。这也可能导致这些动物血压不稳定。
