Background: Women have poorer in-hospital outcomes following coronary artery bypass grafting compared with men although the reasons are unclear. Gender-mediated differences in the vascular reactivity of the arterial conduit may contribute to these differential outcomes. This study investigated gender-dependent differences in the vasoconstrictor responses of the internal mammary artery used for coronary artery bypass grafting.
Methods: Internal mammary artery segments were obtained from patients undergoing coronary artery bypass grafting and subjected to vascular myography. Following assessment of endothelial function, concentration-response curves were determined to noradrenaline, phenylephrine, seotonin, U46619 (thromboxane analogue) and endothelin. The EC50 values for each vasoconstrictor are summarised in the table below, expressed as mean ± SEM (*significant difference between males and females, p < 0.05).
|Males (n = 13)||Females (n = 7)|
|Noradrenaline||0.73 ± 0.25 μM||0.23 ± 0.40 μM|
|Phenylephrine||3.36 ± 0.29 μM||0.36 ± 0.22 μM*|
|U46619||11.29 ± 0.12 nM||2.32 ± 0.41 nM*|
|Serotonin||4.08 ± 0.27 μM||0.16 μM ± 0.10 μM*|
|Endothelin||9.36 ± 1.05 nM||7.65 ± 1.49 nM|
Conclusion: The internal mammary arteries of women are more sensitive to constriction by thromboxane, phenylephrine and serotonin, compared with men. Ongoing studies are evaluating the molecular mechanisms responsible for these differences.
© 2011 Published by Elsevier Inc.