Shizue Masuki, Ph.D.

Postdoctoral fellow

Department of Anesthesiology , Mayo Clinic and Foundation

 

 

Shizue Masuki received her Ph.D. degree from Shinshu University, March 31 2003.  Her thesis "Enhanced baroreflex sensitivity in free-moving calponin knockout mice" was supervised by Hiroshi Nose, professor of Sports Medicine.  At the International Sports Science Forum 2001 she was impressed by the possibility of combining genetic, animal and human studies to address broad research goals and she met Prof. Michael Joyner.  Dr. Masuki is now working with Dr. Joyner as a post-doctoral fellow at Mayo Clinic in Rochester, Minnesota.  Her interests center on the relationship between peripheral adrenergic responses, cardiovascular reflexes and neural control of muscle blood flow during exercise.

 

Reduced alpha-adrenergic vasoconstriction and enhanced cardiac baroreflex sensitivity

Baroreflex control of heart rate varies with activity and can be reset by signals from the uppper brain.  In mice  -adrenergic responses in peripheral vessels show diurnal variation that is matched by compensatory changes in the cardiovagal baroreflex so that arterial pressure is maintained. Enhanced baroreflex control of heart rate is also seen in mice genetically deficient of a-adrenergic vasoconstrictor responses.  Preliminary observations in humans suggest this inverse relationship between alpha-adrenergic vasoconstriction and barofeflex contol of heart rate may explain individual differences in heart rate variability in a manner consistent with both the animal studies and the general idea that a primary change in alpha responsiveness in peripheral vessels evokes a secondary change in barorefles control of HR.