Nebraska Book Company announced Wednesday its intention to amend an $85 million revolving line of credit.

The Lincoln-based owner of more than 270 college bookstores said in a news release it plans to seek a 15-month extension of the credit line beyond its March expiration date.

The company said the amendment will reduce the maximum to $65 million, require it to pay a higher interest rate and put additional restrictions on its ability to expand through acquisitions of new bookstores.

Alan Siemek, Nebraska Book’s chief financial officer, said the changes are necessary to ensure the company keeps the revolving credit line, which it uses “all the time.” Nebraska Book obtained an increase in the maximum borrowing limit from $65 million to $85 million in March 2007.

The company also said its majority owner, Weston Presidio, will invest an additional $10 million in the company. Siemek said that infusion is being required by the provider of the credit line, which he did not name.

The national economic woes and the credit crunch have made it difficult for businesses, even successful ones, to get loans.

Mark Oppegard, Nebraska Book’s CEO, said the company recognizes that fact.

“ It’s important to note that we remain optimistic about the college bookstore business — but we also recognize that the historic disruption of the credit markets and the general economic slowdown means that we need to look hard at everything we do,” Oppegard said in a statement.