Abstract In Ca 2+- and Na +-deficient, isotonic 126 mM K + medium, addition of 5 mM Mn 2+ caused a tension about 2.5× greater than the tonic response induced by 126 mM K + medium (Ca 2+ 2.5 mM, Na + 0 mM) in ileal muscle. When glycogen was depleted by incubation in a glucose-free, isotonic 126 mM K + medium, addition of 5 mM Mn 2+ induced only a very weak tension in Ca 2+-free, isotonic 126 K + medium. Phlorizin (10 −3 M), a blocker of Na +-coupled glucose cotransporter and ouabain (9×10 −5 M), an inhibitor of Na +, K +-ATPase, failed to inhibit the tension elicited by 5 mM Mn 2+ in a Ca 2+- and Na +-deficient, isotonic 126 mM K + medium. Mn 2+ was accumulated in the intracellular compartment in a Ca 2+- and Na +-deficient, isotonic 126 mM K + medium. The tissue ATP concentration was significantly reduced in a Na +-deficient 126 mM K + medium. However, it recovered almost completely when 5 mM Mn 2+ was added to the isotonic 126 mM K + medium. These results suggest that the Mn 2+-induced contraction in depolarized ileal longitudinal muscle in Na +-deficient medium may be maintained by a glucose transport which is not dependent on Na + and insensitive to phlorizin.