RONKONKOMA, N.Y. (AP) ¿ Nutritional-supplement maker and retailer NBTY Inc. said Monday that its April sales rose 13 percent, helped by a solid increase in wholesale U.S. nutrition sales. Total monthly sales grew to $214 million from $189 million, with wholesale U.S. nutrition revenue up 26 percent to $132 million. North American retail sales also climbed, gaining 4 percent to $18 million. The unit's same-store sales, or sales at stores open at least a year, edged up 2 percent. Same-store sales are a key indicator of retailer performance since they measure growth at existing stores rather than newly opened ones. The wholesale U.S. nutrition and North American retail revenue results were able to offset declines in both European retail and direct response, e-commerce sales. European retail revenue dipped 2 percent in April, while direct response, e-commerce sales fell 8 percent. NBTY's stock dropped 62 cents, or 2.4 percent, to $25.07 in morning trading. Over the past year, the shares have traded in a range of $12.22 to $37.26.