The consumption of
all forms of alcohol leads to dilation of the blood vessels and a
short-term drop in blood pressure.
However, the
long-term effects of alcohol consumption (irrespective of whether the alcohol is consumed in whisky or in any other form) include raised blood pressure. (There is also some evidence to suggest that there is a short-term rise in blood pressure, to higher than normal levels, as the body 'bounces back' from alcohol consumption).
For dozens of quotes, from learned sources (which don't always agree with each other), see here:
http://www.jrussellshealth.com/alcbpt.html
Chris