(a) An amendment is effective upon the issuance of a certificate of amendment by the commissioner, or on a later date, not more than 30 days after the filing of the certificate with the commissioner, as provided in the articles of amendment.
(b) An amendment may not affect an existing cause of action in favor of or against the corporation, or a pending suit to which the corporation is a party, or the existing rights of persons other than shareholders. If the corporate name is changed by amendment, a suit brought by or against the corporation under its former name does not abate.