A spokesman for HealthSouth, Andrew Brimmer, said the company ''takes all matters related to Medicare seriously and is cooperating with all government inquiries.'' The House committee has issued subpoenas requesting documents from several former aides of Richard M. Scrushy, the founder and ousted chief executive of HealthSouth. James Goodreau, a former security chief at HealthSouth, and Anthony Tanner, a former corporate secretary, were called to testify at a closed hearing on accusations of fraud involving the timing of Mr. Scrushy's sales of stock and public disclosures, which sent the share price tumbling. Mr. Tanner did not respond to a telephone request for comment last night. Ron Wise, a lawyer in Montgomery, Ala., for Mr. Goodreau, said he and his client would not comment.