Milne B, Quintin L, Gillon J Y
Department of Anesthesia, Queen's University, Kingston, Ont., Canada.
Brain Res. 1990 Jun 4;518(1-2):143-8. doi: 10.1016/0006-8993(90)90965-e.
The objective was to observe changes in rostral ventrolateral medulla (RVLM) catecholamine metabolism using in vivo voltammetry following induced hypotension with halothane or nitroprusside (SNP). Rats anesthetized (halothane, metocurine) and ventilated were stereotaxically implanted with carbon microelectrodes in the RVLM. The catechol oxidation current (CA.OC, % baseline) was used as an index of RVLM catecholaminergic metabolism. Groups of rats (n = 5) were given (A) halothane 0.75% for 60 min; (B) halothane 2.75% plus phenylephrine infusion to maintain mean arterial pressure (MAP) for 30 min, then halothane 0.75% for 30 min; (C) halothane (2.5-3.0%) for 30 min (MAP 60 +/- 5 mmHg) then halothane 0.75% for 30 min; (D) halothane 0.75% and sodium nitroprusside (SNP) for 30 min (MAP 60 +/- 5 mmHg), then halothane 0.75% for 30 min. Halothane 0.75% produced no significant change in CA.OC or MAP (A), while halothane 2.5-3.0% produced a significant decrease in MAP and a symmetrical significant increase in CA.OC (ANOVA, P less than 0.5). This increase peaked at 30 min (180 +/- 28%) and reached 110 +/- 9% baseline at 60 min. The halothane and phenylephrine combination produced no significant change in CA.OC or MAP during the 30 min exposure (B). SNP (D) produced a significant increase in CA.OC (peak 48 min, 224 +/- 35%) which remained elevated at 60 min (198 +/- 32%). Thus, the induced hypotension produced activation of RVLM catecholaminergic neurons. SNP induced a prolonged significant increase in RVLM catecholamine metabolism which may relate to rebound hypertension following use of this drug.
目的是使用体内伏安法观察氟烷或硝普钠（SNP）诱导低血压后延髓头端腹外侧区（RVLM）儿茶酚胺代谢的变化。将麻醉（氟烷、美托咪定）并通气的大鼠立体定向植入RVLM的碳微电极。儿茶酚氧化电流（CA.OC，%基线）用作RVLM儿茶酚胺能代谢的指标。将大鼠分组（n = 5），给予：（A）0.75%氟烷60分钟；（B）2.75%氟烷加去氧肾上腺素输注以维持平均动脉压（MAP）30分钟，然后0.75%氟烷30分钟；（C）2.5 - 3.0%氟烷30分钟（MAP 60±5 mmHg），然后0.75%氟烷30分钟；（D）0.75%氟烷和硝普钠（SNP）30分钟（MAP 60±5 mmHg），然后0.75%氟烷30分钟。0.75%氟烷对CA.OC或MAP无显著影响（A组），而2.5 - 3.0%氟烷使MAP显著降低，CA.OC对称地显著增加（方差分析，P＜0.5）。这种增加在30分钟时达到峰值（180±28%），在60分钟时达到基线的110±9%。在30分钟暴露期间，氟烷和去氧肾上腺素联合使用对CA.OC或MAP无显著影响（B组）。SNP（D组）使CA.OC显著增加（峰值在48分钟，224±35%），在60分钟时仍保持升高（198±32%）。因此，诱导的低血压导致RVLM儿茶酚胺能神经元激活。SNP诱导RVLM儿茶酚胺代谢长时间显著增加，这可能与使用该药物后的反弹性高血压有关。
