Abstract P341: Renal Denervation Prevents Cholinergic Mediated Hypertension and Renal Macrophage Infiltration

Abstract

In vivo cholinergic activation with nicotine induces renal infiltration of M1 inflammatory CD161a+/CD68+ macrophages and the development of hypertension. Renal denervation has been proposed as a treatment for essential hypertension. Based on this we hypothesized that the renal sympathetic nerves play a role in these processes. Bilateral renal denervation was performed surgically in 3-4 week old Spontaneously Hypertensive Rats (SHR), a genetic model of essential hypertension. Following one week recovery, animals received subcutaneous infusion of nicotine (15mg/kg/day) via osmotic pumps for 2 weeks. Blood pressure was measured by tail-cuff and kidneys harvested on completion of infusion. Prior to nicotine infusion, at baseline, there was no difference between the systolic blood pressures of the sham treated (n=7) and renal denervation (n=10) groups, 132 ± 4 vs 128 ± 3 mmHg, respectively (p>0.05). In contrast, nicotine infusion significantly raised the systolic blood pressure in the sham treated group (159 ± 3mmHg), but not in the renal denervation group (135 ± 5 mmHg) (p<0.001). Moreover, nicotine infusion induced a significantly greater infiltration of inflammatory CD161a+ immune cells and CD161a+/CD68+ inflammatory macrophages into the renal medulla of the sham treated group (n=4) (13 ± 2 cells/hpf and 5 ±1 cells/hpf, respectively), compared to renal denervation(n=4) (2 ± 1 cells/hpf and 2 ± 1 cells/hpf) (p<0.001). We conclude that renal sympathetic innervation is required for the nicotine-induced migration of inflammatory CD161a+ immune cells and CD161a+/CD68+ inflammatory macrophages into the renal medulla and that renal denervation prevents the cholinergic-induced renal inflammation and hypertension in this model.