星状神经节阻滞对缺氧性肺动脉高压家兔的血管舒缩因子及肺动脉压的影响

Effects of stellate ganglion block on the plasma concentration of vascular constricting and relaxing factors and pulmonary arterial pressure in rabbits with hypoxic pulmonary hypertension

目的 观察星状神经节阻滞对缺氧性肺动脉高压家兔的血管舒张因子降钙素基因相关肽(CGRP)、前列环素(PGI_2)及血管收缩因子内皮素(ET)、血栓素(TXA_2)以及肺平均动脉压(PMAP)的影响。方法 健康成年日本大耳白家兔在无菌操作下暴露左侧星状神经节,置入并固定硬膜外导管,使其一端开口位于星状神经节附近,另一端自颈背部穿出。置管一周后,选择恢复健康兔24只随机分为四组(每组6只),正常对照组(N)、单纯星状神经节阻滞组(G)、单纯缺氧组(H)、缺氧+星状神经节阻滞组(HG)。用开胸直接测压法测平均肺动脉压(MPAP)、用放射免疫法测 CGRP、PGI_2、ET、TXA_2。结果 H组:与N组相比,肺动脉压显著升高伴有CGRP、PGI_2下降、ET、TXA_2升高(P<0.01);HG组:与H组相比,肺动脉压显著下降(P<0.05)伴有CGRP升高(P<0.01)、ET下降(P<0.05),而PGI_2、TXA_2无明显变化。结论 星状神经节阻滞后,可降低缺氧性肺动脉高压家兔的MPAP,其机制与CGRP升高、ET下降有关。

Objective To investigate the effects of stellate ganglion bloke (SGB) on the plasma concentration of vascular constricting and relaxing factors including calcitonin gene related peptide ( CGRP), endothelin (ET), prostacyclin ( PG 12) and thromboxane A2 (TXA2) and on mean pulmonary arterial pressure (MPAP) in rabbits with hypoxic pulmonary hypertension (HPH) .Methods Twenty-four healthy rabbits of both sexes weighing 2.5-3.0 kg were randomly divided into 4 groups: Ⅰ control group ( N, n = 6); Ⅱ simple SGB group (G, n = 6); Ⅲ HPH group (H, n = 6) and Ⅳ HPH + SGB group (HG, n = 6) . The animals were anesthetized with 1.5% sodium pentobarbital 30 mg·kg-1 iv. Spontaneous breathing was maintained. Left stellate ganglion was exposed aseptically. An epidural catheter was fixed with its tip placed close to the stellate ganglion. The other end was placed outside through a hole in the skin for the administration of drugs. In group Ⅲ and Ⅳ the animals were placed in a hypoxic box (O2 % = 10%±2%) 8h a day for 2 weeks. In group Ⅱ andⅣ 0.25% bupivacaine 0.5 ml was injected through the catheter three times a day for 3 days. In control group and HPH group normal saline 0.5 ml was injected instead of bupivacaine. The effect of SGB was confirmed by ptosis and miosis. The plasma concentrations of CGRP,ET,6-keto-PGF1a and TXB2 were determined by radio-immuno assay.Results In HPH group (group Ⅲ) MPAP and plasma ET,TXB2 levels were significantly higher and plasma CGRP and 6-keto-PGF1a level significantly lower than those in the control group (group Ⅰ ) . In HPH + SGB group (groupⅣ ) after 3 day of SGB, MPAP and plasma ET level were significantly decreased and plasma CGRP level was significantly increased as compared with those in the HPH group but there was no significant difference in 6-keto-PGF1a and TXB2 levels between the two groups. Conclusion SGB can decrease pulmonary hypertension induced by hypoxic pulmonary vasoconstriction and the underlying mechanism, may be related to the increased plasma CGRP and decreased plasma ET level.