【摘要】 研究α₁肾上腺素受体（α₁-AR）不同亚型之间激动剂诱导的减敏和利血平化诱导的增敏过程的差别.方法:采用大鼠离体血管收缩功能实验,观察主动脉、肾动脉和肠系膜动脉在CEC 100 μmol·L^-1温育30 min后,NE介导的累积浓度收缩曲线（CCRC）的变化,以观察不同血管的亚型差异;在观察减敏时,血管用NE 10 μmol·L^-1预温育1 h,洗出后做NE的CCRC;在观察增敏的差异时,大鼠用reserpine 4 mg·kg^-1ip 48 h后,观察NE诱导的CCRC的变化.本实验在灌流液中含yohimbine和propranolol以阻断α₂-和β-AR,这样NE仅激活α₁-AR.结果:CEC 100 μmol·L^-1温育30 min,使NE介导的主动脉,肠系膜动脉的最大收缩分别降低82.5±3.0％和54.2±9.5％,而对肾动脉则无影响,再次肯定主动脉主要含α_1B-AR,肾动脉主要含α_1A-AR,肠系膜动脉兼含两种亚型.NE 10 μmol·L^-1温育1 h后,NE介导的主动脉,肾动脉和肠系膜动脉收缩的敏感性降低,EC₅₀分别增加了14.4±5.9,1.8±0.8和7.3±1.8倍;而在利血平化大鼠NE介导肾动脉收缩反应增加了56％,主动脉则无变化.结论:α_1B-AR亚型介导的反应易发生减敏;a_1A-AR亚型介导的反应易发生增敏.更多还原

【Abstract】 To study the differences of the agonist-induced desensitization and the reserpiniza-tion-induced hypersensitization between a1A-and a1B-adrenoceptors (AR) mediated vasoconstriction. METHODS: The thoracic aor-tae, mesenteric, and renal arteries of rats were isolated. The cumulative-concentration response-curve ( CCRC ) of vasoconstriction for NE was recorded. NE activated only a1-AR since the perfusing Krebs solution contained propranolol 1μmol· L-1 and yohimbine 0.1 μmol· L-1 to block α- and β2-AR. CCRC for NE was made, preparations were pretreat-ed with CEC 50 μmol· L-1 for 30 min or preincubated with NE 10μmol·L-1 for 1 h then washed, and CCRC for NE was repeated. After ip reserpine 4 mg·g-1 ip, the rats were killed, the thoracic aortae and renal ar-feries were taken, CCRC for NE was compared with the corresponding blood vessels in control rats. RESULTS: Pretreatment with CEC caused reductions of the NE-induced maximal - constriction by 82. 5+3. 0 % (P <0. 01) and 54.2+9.5 %(P<0. 01) in thoracic aortae and mesenteric arteries, respectively, but no effect in renal arteries. Prein-cubation with NE caused the α1-AR mediated-vasoconstriction diminished 14.4+5.9,1.8 +0.8 and 7. 3+1. 8 times in aortae, renal arteries, and mesenteric arteries, respectively. In reserpinized rats, the contraction in renalarteries induced by NE increased by 56 %, but showed no change in aortae. CONCLUSION:α1B-AR mediated vasoconstriction is easier to be desensitized, while α1A-AR mediated vasoconstriction is easier to be hypersen-sitized in rats.更多还原