According to the Washington Post, HE detergent can be used in a top loader washer. However, it warns that HE detergents, due to their design, do not generate suds. Also, regular detergent cannot be used in an HE washer.
Use the same amount of HE detergent for a regular, top-loader washer as is directed for an HE washer. Some HE laundry washing detergent manufacturers are starting to label their products to inform consumers that they can be used in regular, non-HE washers. Using regular detergents in an HE machine, however, may void the warranty and cause harm to the washer.