Different responses of the retinal and cutaneous microcirculation to transient dysmetabolic conditions.
OBJECTIVE
This study evaluated the responses of the retinal and cutaneous microcirculation to acute hyperlipidemia and hyperhomocysteinemia.


METHODS
Twenty-five clinically healthy men (mean age 24 ± 2 years) were studied four times in a randomized order, with intervals of at least one week between the two dietary interventions always preceded by a day for baseline assessment. The two interventions consisted of either 0.1 g/kg l-methionine to induce hyperhomocysteinemia or of 500 ml whipping cream (30% fat) to induce hyperlipidemia. Microvascular vasodilator responses to flickering-light and to cutaneous acetylcholine iontophoresis were assessed by retinal vessel analysis and laser Doppler flowmetry respectively.


RESULTS
The fat load produced significant increases in triglycerides and total cholesterol which was accompanied by a reduction of the retinal arterial flicker response. Methionine administration induced a threefold increase in homocysteine levels and a concomitant decrease in retinal venous flicker response. Acute hyperlipidemia and hyperhomocysteinemia had no effect on cutaneous microvascular vasodilator responses to acetylcholine. The inter- and intra-subject reproducibility was higher for retinal vessel analysis as compared to laser Doppler flowmetry.


CONCLUSIONS
The retinal microcirculation is more sensitive to metabolic changes than the cutaneous microcirculation and can be reliably assessed by retinal vessel analysis. Reproducibility of retinal vessel analysis may be enhanced by multi-vessel assessment.
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
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
D000109:Acetylcholine / Q000008:administration & dosage; D000279:Administration, Cutaneous; D000328:Adult; D004041:Dietary Fats / Q000097:blood; D005858:Germany; D006710:Homocysteine / Q000097:blood; D006801:Humans; D020138:Hyperhomocysteinemia / Q000097:blood / Q000139:chemically induced / Q000503:physiopathology*; D006949:Hyperlipidemias / Q000097:blood / Q000139:chemically induced / Q000503:physiopathology*; D007478:Iontophoresis; D017078:Laser-Doppler Flowmetry; D008027:Light; D008297:Male; D008715:Methionine; D008833:Microcirculation / Q000187:drug effects / Q000528:radiation effects; D055806:Microvessels / Q000187:drug effects / Q000503:physiopathology* / Q000528:radiation effects; D010775:Photic Stimulation; D011237:Predictive Value of Tests; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D012171:Retinal Vessels / Q000503:physiopathology* / Q000528:radiation effects; D012867:Skin / Q000098:blood supply*; D014664:Vasodilation / Q000187:drug effects / Q000528:radiation effects; D014665:Vasodilator Agents / Q000008:administration & dosage; D055815:Young Adult
D004041:Dietary Fats; D014665:Vasodilator Agents; D006710:Homocysteine; D008715:Methionine; D000109:Acetylcholine
Iontophoresis; Reproducibility; Retinal vessels; Skin microcirculation