['Small-conductance, Ca(2+)-activated K(+) channel 3 (SK3) has been shown to be expressed in porcine endometrium. However, the roles of SK3 in human endometrium during the menstrual cycle and early pregnancy are unknown.', 'The objective of the study was to investigate the expression and function of SK3 in human endometrium and the mechanism involved.', 'We determined the expression of SK3 in human endometrium by RT-PCR, Western blotting, and immunofluorescence. Using electrophysiological and fluorescent imaging techniques, we investigated the effects of SK3 on the membrane potential and the concentrations of cytosolic calcium, respectively. The effects of SK3 on endometrial thickness and pregnancy outcome were also investigated. Knockdown of endometrial SK3 was used to examine the effects of SK3 on cell migration, cytoskeleton formation, and calcium concentration in the cytosol.', 'SK3 channels are present in human endometrium. In vivo experimental and clinical data demonstrated that the reduced expression of SK3 was associated with a thin endometrium and unsuccessful pregnancy outcomes. Knockdown of human endometrial SK3 attenuated the rise in cytosolic calcium and membrane hyperpolarization induced by thapsigargin, a Ca(2+)-ATPase inhibitor, cell migration, and F-actin assembly. Knockdown of endometrial SK3 in mice also resulted in a thin endometrium and unsuccessful pregnancy outcome.'] Is small-conductance , calcium-activated potassium channel 3 ( SK3 ) a modulator of endometrial remodeling during endometrial growth?