Dev B R, Mason P A, Freed C R
Department of Medicine, University of Colorado Health Sciences Center, Denver 80262.
J Neurochem. 1992 Apr;58(4):1386-94. doi: 10.1111/j.1471-4159.1992.tb11354.x.
Neurochemical changes in the extracellular fluid of the rostral ventrolateral medulla (RVLM) were produced by changes in arterial blood pressure. Blood pressure was raised or lowered with systemic infusions of phenylephrine or nitroprusside and neurochemicals were recovered from RVLM by in vivo microdialysis. A dialysis probe 300 microns in diameter and 500 microns in length was stereotaxically implanted in the RVLM of the urethane-anesthetized rat. Sterile physiological Ringer's solution was perfused at a rate of 1.5 microliter/min. The perfusate was collected under ice-cold conditions every 15 min for the assay of epinephrine, dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindoleacetic acid (5-HIAA), ascorbic acid, and uric acid. After stable baseline neurochemical concentrations were achieved, animals were infused with phenylephrine or nitroprusside intravenously to raise or lower the blood pressure. Increasing blood pressure 50 mm Hg above the baseline value by phenylephrine led to a significant reduction in heart rate and a reduction in extracellular epinephrine and DOPAC concentrations. The 5-HIAA concentration was increased during the hypertensive drug infusion. There were no changes in the concentrations of ascorbic acid or uric acid. Hypotension produced by nitroprusside (-20 mm Hg) led to neurochemical changes which were the reciprocal of those seen during hypertension. During hypotension, heart rate increased as did the extracellular fluid epinephrine concentration. The 5-HIAA concentration fell with hypotension and remained depressed following the nitroprusside infusion. Ascorbic acid and uric acid concentrations did not change during hypotension but ascorbic acid did increase after the nitroprusside infusion stopped. These data provide direct evidence that epinephrine release in RVLM is linked to changes in systemic blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
延髓头端腹外侧区（RVLM）细胞外液中的神经化学变化是由动脉血压变化引起的。通过全身输注去氧肾上腺素或硝普钠来升高或降低血压，并通过体内微透析从RVLM中回收神经化学物质。将一个直径300微米、长度500微米的透析探针立体定位植入经乌拉坦麻醉的大鼠的RVLM。无菌生理林格氏液以1.5微升/分钟的速度灌注。每隔15分钟在冰冷条件下收集灌注液，用于检测肾上腺素、二羟基苯乙酸（DOPAC）、5-羟吲哚乙酸（5-HIAA）、抗坏血酸和尿酸。在达到稳定的基线神经化学浓度后，给动物静脉输注去氧肾上腺素或硝普钠以升高或降低血压。去氧肾上腺素使血压比基线值升高50毫米汞柱，导致心率显著降低，细胞外肾上腺素和DOPAC浓度降低。在输注升压药物期间，5-HIAA浓度升高。抗坏血酸或尿酸浓度没有变化。硝普钠引起的低血压（-20毫米汞柱）导致神经化学变化，与高血压期间所见变化相反。在低血压期间，心率增加，细胞外液肾上腺素浓度也增加。5-HIAA浓度随低血压下降，在硝普钠输注后仍保持降低。低血压期间抗坏血酸和尿酸浓度没有变化，但在硝普钠输注停止后抗坏血酸确实增加了。这些数据提供了直接证据，表明RVLM中的肾上腺素释放与全身血压变化有关。（摘要截短至250字）
