TSX futures muted as commodities decline offset investor optimism

May 8 (Reuters) - Futures for Canada's main stock index were subdued on Wednesday, as optimism for a sustained rally following the index nearing a record high in the previous session was contained by lower commodity prices. June futures on the S&P/TSX index were up 0.1% at 6:45 a.m. ET (10:45 GMT). The Toronto Stock Exchange's S&P/TSX composite index (.GSPTSE) ended 0.1% higher on Tuesday, extending its gains to a fifth session. The index closed at its highest level in four weeks. The index began its rally after the U.S....