Tokyo stocks opened sharply lower Friday as export-related issues were hit after the yen jumped against the U.S. dollar following cooling U.S. inflation data overnight. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 648.83 points, or 1.54 percent, from Thursday to 41,575.19. The broader Topix index was down 25.53 points, or 0.87 percent, at 2,903.64. On the top-tier Prime Market, decliners were led by electric appliance, insurance and bank issues. The dollar briefly plunged by over 4 yen to hit a three-week low of 157.40 yen in New York, as a softer-than-expected J…