How to pass autogenerate gridview column names in view states

Question

How to pass autogenerate gridview column names in view states??? Number of Columns may be vary depending on table Column.... 
I am Loading Dropdownlist with various table names depending on database.... 
On selecting particular table grid view will be generated... And Column names may be vary depending on Table.... 
Now I want to get All Column Names in View State... How to get that??? 
//This Populate Grid View will generate gridview for any Table which is selected

private void PopulateGridView() { 
  try {
  SqlConnection con;
  con = new SqlConnection(@"Data Source=CKQJ8433\SQLEXPRESS;" + "Initial Catalog" + "=" +drddatabase.SelectedValue + ";" + "Integrated Security=True");
  SqlCommand cmd = new SqlCommand();
  cmd.CommandText = "select * from " + drdtablename.SelectedValue;
  cmd.CommandType = CommandType.Text;
  cmd.Connection = con;
  SqlDataAdapter da = new SqlDataAdapter();
  da.SelectCommand = cmd;
  DataSet ds = new DataSet();
  da.Fill(ds, "Disp");
  grdview.DataSource = ds.Tables["disp"];
  Label1.Text = " ";
  //View State to Delete Data From Gridview
  ViewState["arun"] = ds;
  string strColumnsName = ds.Tables[0].Columns[0].ColumnName;
  //ViewState to delete Data From Database
  ViewState["id"] = strColumnsName;
  }
  catch (SqlException ex)
  {
  }
  grdview.DataBind();
  }
  protected void grdview_RowEditing(object sender, GridViewEditEventArgs e)
  {
  //This is Data Set Which I got From PopulateGridView
  DataSet dt = (DataSet)ViewState["arun"];
  //In Employee I am Having 3 Columns... So I write this code
  string colname1= dt.Tables[0].Columns[0].ColumnName;
  ViewState["eid"] = colname1;
  string colname2 = dt.Tables[0].Columns[1].ColumnName;
  ViewState["ename"] = colname2;
  string colname3 = dt.Tables[0].Columns[2].ColumnName;
  ViewState["ecity"] = colname3;
  grdview.EditIndex = e.NewEditIndex;
  PopulateGridView();
  }

This For Particular Employee Table which consist of 3 Columns.... 
For Different Table Columns may be vary....