SharePoint: Make a list field hidden programmatically

SPList myList;
...
SPField titleField = myList.Fields.GetField("Title");
//titleField.PushChangesToLists = true; <-- doesn't seem to make a difference
titleField.ShowInEditForm = false;
titleField.ShowInDisplayForm = false;
titleField.ShowInNewForm = false;
titleField.Update();
//myList.Update(); <-- make no difference

field.Hidden = true;
field.Update();

using (SPSite site = new SPSite(webUrl))
{
    using (SPWeb web = site.OpenWeb())
    {
        try
        {
            //... Get SPList ...
        }
    }
}