A high-fat meal impairs muscle vasodilatation response to mental stress in humans with Glu27 beta2-adrenoceptor polymorphism.
BACKGROUND
Forearm blood flow responses during mental stress are greater in individuals homozygous for the Glu27 allele. A high-fat meal is associated with impaired endothelium-dependent dilatation. We investigated the impact of high-fat ingestion on the muscle vasodilatory responses during mental stress in individuals with the Glu27 allele and those with the Gln27 allele of the beta2-adrenoceptor gene.


METHODS
A total of 162 preselected individuals were genotyped for the Glu27Gln beta2-adrenoceptor polymorphism. Twenty-four individuals participated in the study. Fourteen were homozygous for the Gln27 allele (Gln27Gln, 40 +/- 2 years; 64 +/- 2 kg), and 10 were homozygous for the Glu27 allele (Glu27Glu, 40 +/- 3 years; 65 +/- 3 kg). Forearm blood flow was evaluated by venous occlusion plethysmography before and after ingestion of 62 g of fat.


RESULTS
The high-fat meal caused no changes in baseline forearm vascular conductance (FVC, 2.2 +/- 0.1 vs. 2.4 +/- 0.2; P = 0.27, respectively), but reduced FVC responses to mental stress (1.5 +/- 0.2 vs. 0.8 +/- 0.2 units; P = 0.04). When volunteers were divided according to their genotypes, baseline FVC was not different between groups (Glu27Glu = 2.4 +/- 0.1 vs. Gln27Gln = 2.1 +/- 0.1 units; P = 0.08), but it was significantly greater in Glu27Glu individuals during mental stress (1.9 +/- 0.4 vs. 1.0 +/- 0.3 units; P = 0.04). High-fat intake eliminated the difference in FVC responses between Glu27Glu and Gln27Gln individuals (FVC, 1.3 +/- 0.4 vs. 1.2 +/- 0.4; P = 0.66, respectively).


CONCLUSIONS
These findings demonstrate that a high-fat meal impairs muscle vasodilatation responses to mental stress in humans. However, this reduction can be attributed to the presence of the homozygous Glu27 allele of the beta2-adrenoceptor gene.
Unit of Cardiovascular Rehabilitation and Exercise Physiology, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil. marcia.gowdak@terra.com.br
Marcia M G
MM
Gowdak
Mateus C
MC
Laterza
Maria Urbana P B
MU
Rondon
Ivani C
IC
Trombetta
Alexandre C
AC
Pereira
José Eduardo
JE
Krieger
Carlos Eduardo
CE
Negrão
D000328:Adult; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology*; D005838:Genotype; D006801:Humans; D018482:Muscle, Skeletal / Q000098:blood supply*; D011110:Polymorphism, Genetic; D018343:Receptors, Adrenergic, beta-2 / Q000235:genetics*; D012039:Regional Blood Flow; D013315:Stress, Psychological / Q000503:physiopathology*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
D004041:Dietary Fats; D018343:Receptors, Adrenergic, beta-2