Acute hyperlipidemia but not hyperhomocysteinemia impairs reflex regulation of the cardiovascular system.
BACKGROUND
Elevated circulating lipids and homocysteine may affect autonomic cardiovascular function by decreasing baroreflex sensitivity (BRS) and cardiovagal outflow and by increasing sympathetic drive.


METHODS
To test this hypothesis 25 clinically healthy men (mean age 24 ± 2 years) received 500 ml whipping cream (30% fat) and 0.1 g/kg l-methionine, respectively, at intervals of one week apart to induce hyperlipidemia and hyperhomocysteinemia, respectively. Cardiovascular parameters and endothelial function were assessed before and 2 h after the fat load and before and 4 h after the methionine load, respectively. Cardiovascular responses to sublingual application of a nitrovasodilator and a beta-agonist were also determined.


RESULTS
Hyperlipidemia elicited a significant decline in BRS and an increase in heart rate and sympathetic drive. Reductions in BRS were associated with changes in total cholesterol but not with triglycerides or endothelial function. Autonomic and hemodynamic variables remained unaltered during transient hyperhomocysteinemia although there was a trend to lower BRS. Autonomic and hemodynamic responses to pharmacological vasodilation and beta-adrenoceptor stimulation were preserved under both conditions.


CONCLUSIONS
These data provide experimental support for the concept that acute hyperlipidemia but not hyperhomocysteinemia impairs reflex regulation of the circulatory system.
Autonomic and Neuroendocrinological Laboratory Dresden, Department of Neurology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, 01307 Dresden, Germany. Electronic address: manja.reimann@uniklinikum-dresden.de.
Manja
M
Reimann
Autonomic and Neuroendocrinological Laboratory Dresden, Department of Neurology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, 01307 Dresden, Germany. Electronic address: heinz.ruediger@gmail.com.
Heinz
H
Rüdiger
Division of Angiology, Center for Vascular Medicine and Department of Internal Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, 01307 Dresden, Germany. Electronic address: norbert.weiss@uniklinikum-dresden.de.
Norbert
N
Weiss
Autonomic and Neuroendocrinological Laboratory Dresden, Department of Neurology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, 01307 Dresden, Germany. Electronic address: Tjalf.ziemssen@uniklinikum-dresden.de.
Tjalf
T
Ziemssen
D000318:Adrenergic beta-Agonists / Q000008:administration & dosage; D000328:Adult; D017704:Baroreflex / Q000187:drug effects; D001794:Blood Pressure; D002319:Cardiovascular System / Q000294:innervation*; D004041:Dietary Fats / Q000097:blood; D005858:Germany; D006339:Heart Rate; D006439:Hemodynamics / Q000187:drug effects; D006710:Homocysteine / Q000097:blood; D006801:Humans; D020138:Hyperhomocysteinemia / Q000097:blood / Q000139:chemically induced / Q000503:physiopathology*; D006949:Hyperlipidemias / Q000097:blood / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D008715:Methionine; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D013997:Time Factors; D014630:Vagus Nerve / Q000187:drug effects / Q000503:physiopathology*; D014665:Vasodilator Agents / Q000008:administration & dosage; D055815:Young Adult
D000318:Adrenergic beta-Agonists; D004041:Dietary Fats; D014665:Vasodilator Agents; D006710:Homocysteine; D008715:Methionine
Baroreflex sensitivity; Hyperhomocysteinemia; Hyperlipidemia; Sympathetic nervous system