This study was designed to clarify whether simulated-microgravity-induced differential changes in cerebral and hindlimb arteries could be prevented by daily short-period gravitational loading. We hypothesized that daily short-period restoring the distribution of transmural pressure across arterial vasculature to its normal range by such treatment would be effective in maintaining vessels in their 1 G homeostasis. Tail-suspension (SUS) for 28 d was used to simulate cardiovascular deconditioning due to microgravity. Daily standing (STD) for 1, 2, or 4 h, or +45° head-up tilt (HUT) for 2 or 4 h was used to provide -G_X (dorso-ventral), or +G_Z (footward) gravitational loading as countermeasure. Functional studies showed that SUS alone induced an enhancement and depression in vasoconstrictor responsiveness of basilar and femoral arterial rings, respectively, as previously reported. These differential functional alterations can be prevented by either of the two kinds of daily -G_X and +G_Z gravitational loading treatments. Surprisingly, a daily exposure of as short as 1 h to gravitational loading by STD was sufficient to prevent these differential functional changes in vessels of different regions that might occur due to SUS alone. In morphological studies, the effectiveness of daily 4-h HUT, or 1-h STD in preventing the differential remodeling changes in the structure of basilar and anterior tibial arteries induced by SUS alone was examined by histomorphometry. The results showed that SUS alone induced an increase in the media wall thickness, media cross-sectional area, and number of smooth muscle cell layers in basilar artery, and a decrease in all these parameters in anterior tibial artery. However, both the hypertrophic and atrophic changes that might occur, respectively, in cerebral and anterior tibial arteries due to SUS alone can be prevented not only by daily HUT for 4 h, but also by daily STD even for 1 h. These data indicate that daily gravitational loading by STD for as short as 1 h is sufficient to prevent differential adaptational changes in function and structure of vessels in different regions induced by a medium-term (28-d) simulated microgravity.