How exactly testosterone contribute in the increase of blood pressure ?

Unknown: Thought to be through hormonal mediators which could cause retention of fluids.

Testosterone & HBP: There is still much controversy on this topic The effects of testosterone on blood pressure are many and complex. Men with high blood pressure may be almost twice as likely to have low testosterone as men with normal blood pressure. On the other hand, too much testosterone can increase blood pressure. Testosterone acts in multiple ways on blood vessels, so this may account for the varying effects.