Lipids enhance alpha1-adrenoceptor pressor sensitivity in patients with chronic kidney disease.

Background: Dyslipidemia in patients with chronic kidney disease (CKD) may contribute to hypertension (HT) by altering neurocirculatory control. To test this notion, we quantified the effects of acutely increasing levels of nonesterified fatty acids (NEFAs) and triglycerides on alpha1-adrenergic pressor sensitivity and baroreflex sensitivity (BRS) in subjects without diabetes with CKD.

Methods: Alpha1 pressor sensitivity was determined before and after increasing NEFA and triglyceride levels with a fat emulsion and heparin infusion in 8 subjects with stage 2 to 3 CKD (glomerular filtration rate, 56 +/- 6 mL/min by 125 I-iothalamate clearance). Seven subjects with HT and 8 normotensive control (CO) subjects with normal renal function and matched to patients with CKD also were studied.

Results: Fasting NEFA levels were greater in patients with CKD than in CO subjects (585 +/- 98 versus 321 +/- 32 micromol/L; P < 0.01), but not different from those in subjects with HT (501 +/- 68 micromol/L). Alpha1 pressor sensitivity, defined as the phenylephrine dose that increased mean blood pressure (BP) by 20 mm Hg, was greatest (lowest dose) in subjects with CKD (0.83 +/- 0.11 microg x kg(-1) x min(-1)), followed by those with HT (1.08 +/- 0.19 microg x kg(-1) x min(-1)) and CO subjects (1.34 +/- 0.19 microg x kg(-1) x min(-1); P < 0.05 versus CKD group). BRS, measured as the ratio of change in R-R interval to change in systolic BP during the phenylephrine infusion, was lowest, intermediate, and highest in the CKD, HT, and CO groups, respectively. Increasing NEFA and triglyceride levels significantly enhanced alpha1 pressor sensitivity in all 3 groups and reduced BRS in the CKD and CO groups.

Conclusion: These observations suggest that the dyslipidemia prevalent in patients with stage 2 to 3 CKD may contribute to HT by enhancing alpha1 pressor sensitivity and impairing baroreflex function.