A new brokerage has opened its doors in suburban Maryland. Kent Real Estate, Inc., William Kent Edelen, president, is now in business at 9135 Piscataway Road, Clinton . . . Centennial Development Corp. has broken ground for a 130,000-square-foot office complex in Tysons Corner, to be known as Centennial Plaza II. The new complex will consist of an 80,000-square-foot office tower and 50,000 square feet of condominium office space. Just under half the rental space has been preleased to Compucare, Inc., and to a law firm . . . GATCO Realty Co. of Kensington is introducing a new service to put owners and renters of resort property in touch with each other. Resort Rentals will provide a publication in which owners can buy a year-long ad to describe their properties and rents, and with which renters can comparison shop. If a renter likes a property, he contacts Resort Rentals to determine if it is still available. If it is, Resort Rentals brings owner and renter together and they make their own deal . . . Emanuel A. Baker Jr., president of Town & Country Realtors presented a total of more than $36,000 to Children's Hospital to kick off this year's fund drive to aid the hospital. The money was donated on behalf of sales associates, employes, customers and friends of the area real estate company . . . BTR Realty, Inc. of Baltimore has declared a two-for-one stock split for shareholders of record as of Dec. 13 . . . Brannock Associates announces that the General Services Administration has leased 19,900 square feet for the Nuclear Regulatory Commission at 8120 Woodmont Ave., Bethesda, from Bethesda Associates . . . The Downtown Storage Center, a self-storage facility for law firms, trade associations and other professional groups, has completed its first year of operation. Downtown Storage is a joint venture of the Charles C. Wilkes Development Co. and Fitzgerald Moving Co.