Stress susceptibility as a determinant of endothelium-dependent vascular reactivity in rat mesenteric arteries

Male-specific association between a gamma-secretase polymorphism and premature coronary atherosclerosis

BACKGROUND

Atherosclerosis is a common multifactorial disease resulting from an interaction between susceptibility genes and environmental factors. The causative genes that contribute to atherosclerosis are elusive. Based on recent findings with a Wistar rat model, we speculated that the gamma-secretase pathway may be associated with atherosclerosis.

METHODOLOGY/PRINCIPAL FINDINGS

We have tested for association of premature coronary atherosclerosis with a non-synonymous single-nucleotide polymorphism (SNP) in the gamma-secretase component APH1B (Phe217Leu; rs1047552), a SNP previously linked to Alzheimer's disease. Analysis of a Dutch Caucasian cohort (780 cases; 1414 controls) showed a higher prevalence of the risk allele in the patients (odds ratio (OR) = 1.35), albeit not statistically different from the control population. Intriguingly, after gender stratification, the difference was significant in males (OR = 1.63; p = 0.033), but not in females (OR = 0.50; p = 0.20). Since Phe217Leu-mutated APH1B showed reduced gamma-secretase activity in mouse embryonic fibroblasts, the genetic variation is likely functional.

CONCLUSION/SIGNIFICANCE

We conclude that, in a male-specific manner, disturbed gamma-secretase signalling may play a role in the susceptibility for premature coronary atherosclerosis.

Phenylephrine-induced vasoconstriction of the rat superior mesenteric artery is decreased after repeated swimming

This study was performed to determine the effect of forced swimming on the vascular responsiveness of the rat superior mesenteric artery to phenylephrine, focusing on the involvement of locally produced substances. Repeated but not single sessions of forced swimming exercise reduced the vasoconstrictor potency of phenylephrine in the studied arteries, regardless of the presence of intact endothelium. No significant changes were observed in the maximal response to phenylephrine. Treatment with indomethacin (1 microM) did not affect the exercise-induced reduction in vascular responsiveness to phenylephrine. However, the reduction of vascular reactivity to phenylephrine due to repeated exercise was no longer observed after treatment with N(G)-monomethyl-L-arginine (L-NMMA, 100 microM). The results suggest that repeated exercise reduces vasomotor responses to phenylephrine in rat superior mesenteric arteries through a non-endothelial nitric oxide (NO)-related mechanism.