Attenuation of the exercise pressor reflex. Effect of opioid agonist on substance P release in L-7 dorsal horn of cats.
Attenuation of the exercise pressor reflex. Effect of opioid agonist on substance P release in L-7 dorsal horn of cats.
复制标题
运动加压反射减弱。
DOI：
10.1161/01.res.77.2.326
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发表时间：
1995
影响因子：
20.1
通讯作者：
Wilson,LB
中科院分区：
文献类型：
--
作者：
Meintjes,AF;Nóbrega,AC;Fuchs,IE;Ally,A;Wilson,LB
用α-氯醛糖麻醉的猫，研究了微透析μ-阿片受体激动剂[d-Ala 2]-蛋氨酸脑啡酰胺（DAME，200 μmol/L）至脊髓L-7背角前后，小腿三头肌静态收缩和被动牵拉对血压和心率的反应。此外，我们测量了收缩诱导的P物质释放在背角之前和之后的药物输送。阿片类激动剂透析92±3分钟后，收缩诱导的平均动脉压和心率增加分别从对照值58±7 mm Hg和17±3次/分钟减弱至给药后值27±7 mm Hg和10±2次/分钟。在透析97±5分钟后，观察到被动肌肉拉伸的类似衰减（对照组，38±4 mm Hg和8±2次/分钟;给药后，23±4 mm Hg和5±1次/分钟）。μ受体拮抗剂纳洛酮（300 μmol/L）的预先微透析可阻断这种效应，提示阿片受体激动剂具有特异性受体作用。纳洛酮单独使用对升压或心动过速反应无影响。收缩诱导的P物质样免疫反应性增加由DAME的对照值0.119±0.024降至0.047±0.010 fmol/100 μL。时间控制实验表明，P物质样免疫反应性的释放没有减少。因此，阿片受体的激活通过L-7背角调节III和IV组肌肉传入神经活动的传递。突触前抑制P物质从肌肉传入的释放是DAME的潜在作用机制。
Using α-chloralose–anesthetized cats, we studied blood pressure and heart rate responses to static contraction and passive stretch of the triceps surae muscle before and after microdialyzing the μ-opioid agonist [d-Ala2]-methionine enkephalinamide (DAME, 200 μmol/L) into the L-7 dorsal horn of the spinal cord. In addition, we measured contraction-induced substance P release in the dorsal horn before and after drug delivery. After 92±3 minutes of dialyzing the opioid agonist, contraction-induced increases in mean arterial pressure and heart rate were attenuated from control values of 58±7 mm Hg and 17±3 beats per minute to postdrug values of 27±7 mm Hg and 10±2 beats per minute, respectively. A similar attenuation was observed for the passive muscle stretches after 97±5 minutes of dialysis (control, 38±4 mm Hg and 8±2 beats per minute; after drug, 23±4 mm Hg and 5±1 beats per minute). Prior microdialysis of naloxone (300 μmol/L), a μ-antagonist, blocked this effect, suggesting that the opioid agonist has a specific receptor action. Naloxone alone had no effect on the pressor or tachycardiac responses. The contraction-induced increase in substance P–like immunoreactivity was reduced from a control value of 0.119±0.024 to 0.047±0.010 fmol/100 μL by DAME. Time-control experiments revealed no decrease in the release of substance P–like immunoreactivity. Thus, activation of opioid receptors modulates the transmission of group III and IV muscle afferent nerve activity through the L-7 dorsal horn. Presynaptic inhibition of substance P release from muscle afferents is a potential mechanism of action for DAME.