Edwall B, Gazelius B
Department of Pharmacology, Karolinska Institute, Stockholm, Sweden.
Acta Odontol Scand. 1988 Jun;46(3):127-33. doi: 10.3109/00016358809004758.
Blood flow changes in the periodontal ligament (PDL) were measured indirectly by monitoring the local clearance of 125I- during electric sympathetic nerve stimulation or close intra-arterial infusions of either noradrenaline (NA) or adrenaline (ADR) before and after administration of phentolamine (PA), phenoxybenzamine (PBZ), or Idazoxan (RX). At the doses used in the present study, PA was the only antagonist that significantly reduced the blood flow decrease seen on activation of sympathetic fibers, although PBZ also reduced this response. Idazoxan, however, did not induce the consistent effect on blood flow decreases seen on sympathetic activation. All three alpha-adrenoceptor antagonists almost abolished the effects of exogenously administered NA and ADR. The results suggest the presence of functional post-junctional adrenoceptors of both the alpha 1 and alpha 2 subtypes in the sympathetic regulation of blood flow in the PDL of the cat. A component of the response elicited by electrical sympathetic stimulation appeared to be resistant to alpha-adrenoceptor blockade. Administration of guanethidine (which inhibits further release of NA and neuropeptide Y) after PA abolished this residual sympathetic response.
在给予酚妥拉明（PA）、酚苄明（PBZ）或咪唑克生（RX）之前及之后，通过监测电刺激交感神经或经动脉内近距离输注去甲肾上腺素（NA）或肾上腺素（ADR）期间牙周韧带（PDL）中125I-的局部清除率，间接测量PDL中的血流变化。在本研究使用的剂量下，PA是唯一能显著减轻交感神经纤维激活时所见血流减少的拮抗剂，尽管PBZ也能减轻这种反应。然而，咪唑克生对交感神经激活时所见的血流减少并未产生一致的影响。所有三种α-肾上腺素能受体拮抗剂几乎完全消除了外源性给予NA和ADR的作用。结果表明，在猫PDL的血流交感神经调节中存在功能性的α1和α2亚型节后肾上腺素能受体。交感神经电刺激引发的反应的一部分似乎对α-肾上腺素能受体阻断具有抗性。在PA之后给予胍乙啶（其抑制NA和神经肽Y的进一步释放）消除了这种残余的交感神经反应。
