ffiljc toasijutgton {Jolt )
American businesses experienced a sharp pileup of inventories in April in the face of declining sales, but analysts said overall stockbuilding still wasn't excessive and didnÛªt constitute a serious problem.</br></br>Commerce Department figures showed inventories swelled by $5.9 billion, or 1.3 percent, the largest rise in nine months, pushing the closely watched inventories-to-sales ratio to 1.51. from 1.44 in MarchÛÓthe steepest monthly jump since 1967.</br></br>Separately, the Labor Department reported that initial claims for state imemplovment insurance fell by 48,-000 in the week ended May 31, possibly signaling a slowdown in the recent surge in the nationÛªs unemployment rate.</br></br>At the same time, First National Bank of Boston, the nationÛªs 17th largest commercial bank, lowered its prime lending rate to 12 percent, but it still wasnÛªt clear late yesterday how quickly other banks would follow.</br></br>Meanwhile, the Labor Department published an industry-by-industry breakdown of productivity growth during 1979, showing sharp gains in the railroad and aii-line industries and visible declines in the service sector of the economy.