In the wikipedia article on the Arkansas Milita in the Civil War, one of the tables attempts to show what became of the companies that were in the orgional state troops. This table is not complete, as I have yet to make my way completely through the "List of Militia Commissions", but it does show that a few of the companies almost immediately reformed and reenlisted. I agree with Doyle that most eventually returned to service, but many probably waite until the summer of 1862 and the on set of conscription. I would point out that as I understand it, the State Troops Regiments were mustered out at Fort Smith, not Little Rock.