[Igor (OP)]

Do electronic muscle stimulation devices cause the bloodvessels in the skin to constrict (a.k.a. vasospasm, a.k.a. blanching) ?. If not why not?: they cause the skeletal muscles to contract then why not the smooth muscle in the blood vessels.

http://www.tens-store.com/ems/ems-faq.htm

[RD]

Smooth and skeletal muscles have different response times.
A short pulse of electricity (say 1/100th of a second) could activate the skeletal muscle,
 but be too brief to activate the slower reacting smooth muscle, (speculation).