Comparison of Dexmedetomidine and Remifentanil on Adropin Expression in Unilateral Lumbar Microdiscectomy: A Prospective Active Controlled Randomized Trial Study

<b>Background/Objectives:</b> Remifentanil and dexmedetomidine are widely used agents for pain management during general anesthesia. Adropin acts as a regulator of endothelial function by affecting nitric oxide bioavailability and various hemodynamic factors, including blood flow, vascular dilatation, and mean arterial pressure. We aimed to evaluate the effects of remifentanil and dexmedetomidine on adropin and eNOS levels and hemodynamic parameters in patients undergoing unilateral single-level lumbar microdiscectomy under controlled hypotension. <b>Methods:</b> This study included 40 patients who underwent lumbar microdiscectomy and were randomly assigned to two groups: 20 patients received remifentanil, and 20 received dexmedetomidine. Hemodynamic parameters, preoperative and postoperative VAS scores, and intraoperative blood loss were recorded. Adropin and eNOS mRNA levels were measured with RT-qPCR at three time points: preoperative (T1), intraoperative (T2), and postoperative (T3). Adropin protein levels were evaluated using ELISA. <b>Results:</b> The remifentanil and dexmedetomidine groups had similar heart rate, arterial pressure, intraoperative blood loss, surgery time, and VAS scores. The extubation time was longer with remifentanil. Adropin mRNA level was higher in remifentanil at all time points. At T2, the eNOS mRNA level was higher in the remifentanil group. In the dexmedetomidine group, adropin mRNA levels decreased at T2 compared to T1. Adropin protein levels were higher in the remifentanil group at T2 and T3. In the dexmedetomidine group, serum adropin levels decreased at T3 compared to those at T1. Preoperative VAS scores in patients receiving both remifentanil and dexmedetomidine were higher than postoperative VAS scores. No significant correlation was observed between VAS scores and adropin levels or between intraoperative blood loss and adropin protein levels. <b>Conclusions:</b> Both drugs demonstrated similar effects on the hemodynamics of the patients, and adropin levels were not associated with the VAS score and intraoperative blood loss. These findings suggest that dexmedetomidine mediates vasodilation through adropin-independent mechanisms, while remifentanil may provide more favorable surgical conditions through adropin in patients undergoing unilateral single-level lumbar microdiscectomy.