It was shown that platelet aggregation in partially (with stellate ganglia containing 25% neurons of normal amount) and completely (0,5% neurons) sympathectomized rats was significantly lower than in intact animals. Concurrently the blood coagulation system of sympathectomized rats was hyperactive. The reasons for sympathectomy-induced changes seems likely to be elevated adrenalin blood concentration in such rats.
http://www.ncbi.nlm.nih.gov/pubmed/7388153