The University of Minnesota filed a 300-page response late Tuesday to an inquiry from a prominent U.S. senator who is probing financial relationships between medical device companies and doctors, including one at the university's medical school.

Sen. Charles Grassley, R-Iowa, appears particularly interested in the alliance between Fridley-based Medtronic Inc. and Dr. David Polly, a prominent surgeon who heads the medical school's spine surgery unit.

In a letter dated Aug. 25, university General Counsel Mark Rotenberg said Polly disclosed his relationship with Medtronic both in research grants and while participating in clinical studies.

Previous correspondence between Grassley's office and the U indicated that Medtronic paid Polly about $1.2 million from 2003 to 2007 for consulting services, honoraria and expenses. For four consecutive years, Polly received more than $200,000 annually from Medtronic.

Medical device makers such as Medtronic say such consulting relationships help them understand how their products work in the field and how they can be improved. Critics, however, say the arrangements may constitute a conflict of interest that can negatively affect patient care.

Late last month, Grassley sent a 142-page letter to university President Robert Bruininks asking how the school manages potential conflicts of interest in these relationships, as well as specific questions regarding Polly's role in several research studies.

The U has already launched its own investigation into Polly's compliance with its conflict of interest policies. Medtronic also is investigating Polly's billings.

In his response, Rotenberg noted that the U requires faculty and staff to complete a form disclosing professional activities and business and financial interests of a "significant" nature -- defined as $10,000 or a 5 percent equity stake in a company. About 9,000 U employees must complete this form.

Employees involved in research studies must also disclose any financial ties. The U said several committees review and manage potential conflicts.

The reports are not available to the public, but Rotenberg noted that the U supports pending federal legislation co- sponsored by Grassley that would publicly disclose consulting relationships between doctors and drug and medical device companies.

A good portion of the U's letter responds to specific questions about four research grants Polly received since 2004, three of which involved Medtronic products.

In one study using Medtronic imaging equipment, Polly was advised by the U that he could not serve as the principal investigator and was barred from data collection and analysis, according to the letter.

In 2006, the university's Conflict Review and Management Committee determined that a conflict existed because Polly was a paid Medtronic consultant while also the primary investigator in a study using a Medtronic bone-growth product in rats that was sponsored by a $446,000 Department of Defense grant. The committee and Polly agreed to a conflict management plan.

Documents released by the U also revealed that Polly entered into a "Master Research Agreement" with Medtronic in 2005 as a principal investigator. Although it was set up as an umbrella agreement for future research to be funded by the company, the U said no funds were ever disbursed.

Grassley also asked whether Polly violated guidelines governing clinical trials by failing to report his Medtronic ties to an Institutional Review Board, an ethics committee that monitors research. The U responded that Polly served as principal investigator in seven studies since 2004, reporting a potential conflict in five studies, and no conflict in two.

Janet Moore • 612-673-7752