In a move to cut long-term borrowing costs, the University last week refinanced $146 million of a $229-million 1982 bond issue that went to pay for laboratory and House renovations and projects at the Medical and Business Schools.

The original $229 million issue--known as Series E--carries a fixed rate. Financial Vice President Thomas O'Brien said the refinanced portion carries a variable rate, which will effectively reduce Harvard's borrowing costs over the 30-year life of the bonds.

With more than $640 million in bond issues outstanding. Harvard currently carries the biggest debt load of any university in the country.

A major portion of that debt came when the University in August 1983 sold $350 million in bonds to pay for the construction and interest costs on the Medical Area Total Energy Plant (MATEP).