Section 80I. When a law or rule requires a signature, certification, stamp, verification, affidavit or endorsement by a physician, when relating to physical or mental health, that requirement may be fulfilled by a nurse practitioner practicing under section 80B. Nothing in this section shall be construed to expand the scope of practice of nurse practitioners. This section shall not be construed to preclude the development of mutually agreed upon guidelines between the nurse practitioner and supervising physician under section 80E.