在C#中实现接口时，如何在同一接口的方法中调用接口的属性

大家好，
我想知道如何在同一接口的方法(在先前接口属性的同一类中)调用接口的属性(在实现该接口的类中定义)
这是代码:

Hi All,
m wondering how I can call an Interface''s Property (that is defined in a class that implements that interface) in the same Interface''s method (in the same class of the previous Interface''s property)
Here is the code:

namespace interfacetest
{
  public interface IocExt
  {
    void LoadProperties();
    void UpdateProperties();
    string Properties
    { get; }
  }
  public class ocExt : IocExt
  {
    public string colNameGUID;
    void IocExt.LoadProperties()
    {
       colNameGUID = "GUID";
       Messagebox.Show("LoadProperties()- colNameGUID = " + colNameGUID);
    }
    string IocExt.Proeprties
    {
       get{ return colNameGUID; }
    }
    void IocExt.UpdateProperties()
    {
      IocExt ext = new ocExt();
      string s = "UpdateProperties()- colNameGUID = " +   ext.Properties; // here is the problem: 'colNameGUID' value
                                           could not be retrieved from LoadProeprties that is = "GUID" and it just has " "
      Messagebox.Show(s);
    }
  }
  public partial class ocExtImplement : Form
  {
    private void button3_click(object sender, EventArgs e)
    {
      IocExt ioc = new ocExt();
      ioc.LoadProperties();
      ioc.UpdateProperties();
    }
  }
}

输出:
LoadProperties()-colNameGUID = GUID
UpdateProperties()-colNameGUID =.
我期望第二行也应该显示UpdateProperties()-colNameGUID = GUID. (而不是空白值)
关于如何在IocExt.UpdateProperties()中调用字符串IocExt.Proeprties的任何想法?
提前谢谢！

[edit]添加了代码块以保留格式-OriginalGriff [/edit]

Output:
LoadProperties()- colNameGUID = GUID
UpdateProperties() - colNameGUID = .
I''m expecting the second line should also display UpdateProperties() - colNameGUID = GUID. (instead of blank value)
Any ideas of how I can call string IocExt.Proeprties at IocExt.UpdateProperties()?
Thanks in advance!

[edit]Code block added to preserve formatting - OriginalGriff[/edit]