The people have spoken

If the UK Parliament get to vote on Article 50, I think every MP that sits in a 'Leave' Constituency and votes to block Brexit against the will of the people he represents in his area must resign! How on earth can a democratic institution tolerate its representatives voting against their own people. It is the same with the US Electoral College. If a State voted for Trump, then it is the duty of the Electors of that State to vote with the people's decision. Agreed or not?