Ketamine對腎血流和腎交感神經的作用有不一致的表現

Differentiation of Ketamine Effects on Renal Nerve Activity and Renal Blood Flow in Rats

背景：Ketamine隨著劑量增加，對血壓及交感神經活性已知具雙向效果。在此動物實驗中，我們假設腎血流和腎動脈阻力為腎交感神經所主控，檢驗不同劑量ketamine對腎血流的影響是否和交感神經作用一致。方法：使用十六隻以urethane麻醉並置入動脈導管之大白鼠，其中八隻用以神經紀錄來直接測量腎交感神經活性、另外八隻用electromagnetic flowmeter來測量腎血流，並算出腎血管阻力。Ketamine的劑量均為每隔30分鐘靜脈注射每公斤0.5，1，2毫克。結果：隨著ketamine劑量的增加，血壓及交感神經活性呈現雙向反應；腎血流隨著ketamine劑量的增加而逐漸減少，腎動脈阻力隨著ketamine劑量的增加而逐漸增加，並未呈現雙向變化。結論：隨著ketamine劑量的增加，對腎血流和腎動脈阻力的影響逐漸加大，表示ketamine對腎血流和腎動脈阻力的作用不只受到交感神經的控制。

Background: A biphasic pattern in the effects of increasing dose of ketamine on mean arterial blood pressure (MBP) and renal sympathetic nerve activities (RSNA) was shown in previous study. We hypothesized that if renal vascular resistance (RVR) and renal blood flow (RBF) are mainly controlled by RSNA, they will show a similar biphasic pattern under increasing doses of ketamine. Methods: 16 female Wistar rats anesthetized with urethane were studied for ketamine at 0.5,1, 2 mg/kg, i.v. at 30 min intervals. Multifiber RSNA recording was studied in 8 rats and RBF (by electromagnetic flowmeter) and RVR were studied in the other 8 rats with intact renal nerves. Results: Our results showed that although incremental doses of ketamine brought about a biphasic pattern in MBP and RSNA, the decrease in RBF and the increase in RVR went a dose-related way. Conclusions: We concluded that there was a differentiation of ketamine effects on renal nerve activity and renal blood flow in rats. The changes of RBF and RVR can not only be attributed to the effects of sympathetic nerve activities.