Whole Foods Market Inc shares rose 8.1 percent on Wednesday after accelerating sales eased worries that the gains that have driven a 90 percent one-year stock rise were ending.

Sales at the upscale grocer were the latest sign that better-off U.S. shoppers were spending more money, contrasting with discounter Wal-Mart Stores Inc , which still sees signs that customers are running short of cash at the end of the month.

Shares in Whole Foods, which raised its 2011 profit outlook on Wednesday after reporting first-quarter income that topped Wall Street's view, rose to $58.11 in after-hours trading from their Nasdaq close of $53.60.

Closely watched sales at established stores rose 9.1 percent in the fiscal first quarter, which ended January 16, compared with 8.7 percent in the prior quarter.

Whole Foods, the biggest seller of organic and natural food products in the United States, also said same-store sales were up 8.7 percent so far in the second quarter.

They are continuing their sales momentum into the current quarter, said Hapoalim Securities analyst Ajay Jain.

Wall Street had worried that the company's industry-leading same-store sales growth rates would slow because they were coming up against strong results from a year ago.

On Wednesday, Whole Foods, based in Austin, Texas, posted net income available to common shareholders of $88.7 million, or 51 cents per share, for its fiscal first quarter. That compared with $49.7 million, or 32 cents, a year earlier.

Analysts, on average, had expected a profit of 46 cents, according to Thomson Reuters I/B/E/S.

Sales rose 14 percent to $3 billion.

(Reporting by Lisa Baertlein; Editing by Steve Orlofsky)