Cunnane S C, Manku M S, Oka M, Horrobin D F
Can J Physiol Pharmacol. 1980 Mar;58(3):287-93. doi: 10.1139/y80-049.
The mesenteric vascular bed preparation of control and pinealectomized (PX) male Wistar rats was used to examine vascular reactivity to two concentrations each of norepinephrine, serotonin, angiotensin, and potassium. Vasoconstrictor responses to 50- and 100-ng injections of norepinephrine and 0.5- and 1.0-microgram injections of serotonin were 30-40% higher in preparations from PX rats. Reponses to 100 ng but not to 50 ng of angiotensin were also significantly higher in preparations from PX rats. Responses to 1.5- and to 3.0-mg injections of potassium did not differ significantly in either case. In vivo injection of 20 microgram of melatonin 3 h prior to dissection of the preparation, or in vivo perfusion of 20 ng melatonin per millilitre of buffer completely reversed the increased vascular response to all vasoconstrictor agents tested in the PX preparations, but had little effect in control preparations. Also observed in PX rats was a significant increase in blood pressure, serum sodium, and increased body and heart weight. Arterial wall sodium was also elevated in PX rats. These changes may be relevant to the increased vascular reactivity of PX rats. The increased vascular responsiveness of PX rats may be specific for agents that stimulate calcium release from intracellular stores (norepinephrine, angiotensin) rather than those that stimulate calcium influx from extracellular fluid (potassium). Melatonin lack may be the cause of the vascular changes in the PX rats as both in vivo and in vitro it lowered the vasoconstrictor effects of the agents tested, but only in PX rats; it had no significant effect in the control rats.
采用对照和松果体切除（PX）雄性Wistar大鼠的肠系膜血管床制备物，来检测血管对去甲肾上腺素、5-羟色胺、血管紧张素和钾离子两种浓度的反应性。PX大鼠制备物中，对50 ng和100 ng去甲肾上腺素注射以及0.5 μg和1.0 μg 5-羟色胺注射的血管收缩反应高出30%-40%。PX大鼠制备物中，对100 ng而非50 ng血管紧张素的反应也显著更高。两种情况下，对1.5 mg和3.0 mg钾离子注射的反应均无显著差异。在制备物解剖前3小时体内注射20 μg褪黑素，或在每毫升缓冲液中体内灌注20 ng褪黑素，可完全逆转PX制备物中对所有测试血管收缩剂的血管反应性增加，但对对照制备物几乎没有影响。在PX大鼠中还观察到血压、血清钠显著升高，体重和心脏重量增加。PX大鼠的动脉壁钠含量也升高。这些变化可能与PX大鼠血管反应性增加有关。PX大鼠血管反应性增加可能对刺激细胞内钙释放的药物（去甲肾上腺素、血管紧张素）具有特异性，而不是对刺激细胞外液钙内流的药物（钾离子）。褪黑素缺乏可能是PX大鼠血管变化的原因，因为无论在体内还是体外，它都降低了测试药物的血管收缩作用，但仅在PX大鼠中；对对照大鼠没有显著影响。
