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Background-NO-induced dilations in resistance arteries (RAs) are not associated with decreases in vascular smooth muscle cell Ca 2ϩ . We tested whether a cGMP-dependent activation of the smooth muscle myosin light chain phosphatase (MLCP) resulting in a Ca 2ϩ desensitization of the contractile apparatus was the underlying mechanism and whether it could be antagonized by the RhoA pathway. Methods and Results-The Ca 2ϩ sensitivity of RA was assessed as the relation between changes in diameter and [Ca 2ϩ ] i in depolarized RA (120 mol/L K ϩ ) exposed to stepwise increases in Ca