Chemical sympathectomy with 6-OHDA increased lumen diameters, reduced vascular wall expansion and renal vascular resistance, and increased renal blood flow and GFR in Dahl rats on a HS-LK diet.
Does chemical sympathectomy with 6-OHDA improve renal vascular structure and haemodynamics in Dahl rats on a high salt-low potassium diet?
Sympathetic nervous system activity contributes to the adverse renal vascular remodelling and haemodynamic changes induced by a high salt-low potassium diet in Dahl rats.
OBJECTIVE: A dietary combination of high salt and low potassium (HS-LK) exacerbates hypertension in Dahl salt-sensitive (DS) rats and renders Dahl salt-resistant (DR) rats hypertensive. In both strains, the hypertension is accompanied by remodelling of the renal resistance vasculature, and is attenuated by peripheral chemical sympathectomy. In the current study, we sought to determine whether the sympathetic nervous system is causally involved in mediating the renal vascular and haemodynamic alterations associated with HS-LK feeding in Dahl rats. DESIGN: Two groups each of DS and DR rats were maintained on HS-LK diet (8% NaCl, 0.2% KCl) for 8 weeks. One group of DS (n = 9) and DR (n = 8) were treated with 6-hydroxydopamine (6-OHDA) in 0.001 N HCl vehicle to chemically ablate peripheral sympathetic nerve terminals. The two remaining groups (n = 8 each) received equivalent injections of vehicle. METHODS: At the end of the dietary regimen, arterial blood pressure (ABP), glomerular filtration rate (GFR) and renal blood flow (RBF) were measured, and the structure of intra-renal resistance vessels was examined by planar morphometric analysis of coronal sections prepared from perfusion-fixed kidneys. RESULTS: Both 6-OHDA-treated and untreated DS rats presented a greater degree of intra-renal vessel remodelling characterized by reduced lumen diameter in the absence (eutrophic) or presence (hypertrophic) of cross-sectional area expansion, higher renal vascular resistance (RVR) and lower GFR and RBF than DR rats. Chemical sympathectomy increased lumen diameters and reduced vascular wall expansion, resulting in a decrease in RVR and a concomitant increase in RBF and GFR in both strains; however, the effect was more prominent in the DS rats. CONCLUSIONS: We conclude that HS-LK-induced changes in intra-renal vessel structure and renal haemodynamic function in Dahl rats are, at least in part, dependent on the activity of the sympathetic nervous system.
Wu et al. (Thu,) conducted a other in Hypertension and renal vascular remodelling (n=33). Chemical sympathectomy with 6-hydroxydopamine (6-OHDA) vs. Vehicle injection was evaluated on Arterial blood pressure, glomerular filtration rate, renal blood flow, and intra-renal resistance vessel structure. Chemical sympathectomy with 6-OHDA increased lumen diameters, reduced vascular wall expansion and renal vascular resistance, and increased renal blood flow and GFR in Dahl rats on a HS-LK diet.