Nashville-based HCA Inc. has announced that it would pay interest coming due in spring 2009 on $1.5 billion of debt with more bonds to conserve cash as the hospital chain tries to navigate through an uncertain credit market. On May 15, holders of HCA bonds that mature in 2016 are due $72 million in cash. Now, they are slated to get bonds instead at a higher interest rate that will be worth $6 million more. "Given all of the dramatic turmoil in the capital markets over the last couple of months, it is the prudent thing to do right now," Jack O. Bovender Jr., HCA's chief executive said in a conference call with analysts after the company released third-quarter earnings. "We're not in any way signaling or anticipating any significant decrease in our business next year."