VS 2010 - Getting List Item From DataGridview

Basically, I have a gridview table with a dropdownlist column and I need a way to retrieve the selected item from it. Now I'm using an imagebutton in order to get the selected item from the dropdownlist to pop-up as a message box (as a string). I already know how to get text from a boundfield. However, using the same code to get the dropdown list item won't work. This is a snippet from my code:

ASP code:

Select...
8:00
9:00
10:00
11:00
12:00
1:00
2:00
3:00
4:00

Visual Basic code:

<asp:BoundField DataField="Case#" HeaderText="Case#" ReadOnly="True" />
<asp:TemplateField HeaderText="Surgery Time">
<ItemTemplate>
<asp:DropDownList ID="Time_Slot" runat ="server">
<asp:ListItem Selected="True" Value="0">Select...</asp:ListItem>
<asp:ListItem Value="1">8:00</asp:ListItem>

[CODE]....