261A.49  Bondholders — pledge — agreement of the state.
  The state pledges to and agrees with the holders of any obligations issued under this division, and with those parties who enter into contracts with the authority pursuant to this division, that the state will not limit or alter the rights vested in the authority until the obligations, together with the interest on the obligations, are fully met and discharged and the contracts are fully performed on the part of the authority, except that this section does not preclude the limitation or alteration if and when adequate provision is made by law for the protection of the rights of the holders of the obligations of the authority or those entering into contracts with the authority.
85 Acts, ch 210, §19