Rat brain slices were incubated with substance P (SP), and the SP receptors on the membranes from those slices were characterized by a 3H-SP binding technique. The number of substance P receptors measured in the extensively washed membrane preparations pretreated with 3 x 10(-5) M SP was reduced by 30% compared with that in nontreated membranes. This reduction was dependent on the incubation time and temperature. The metabolic inhibitors sodium azide and 2,4-dinitrophenol protected SP receptors from the reduction. The characteristics of 3H-SP incorporation into rat brain slices were similar to those of SP receptor down-regulation, that is, the 3H-SP incorporation was time, temperature, and energy dependent. Thus these results indicate that the processes of ligand incorporation and receptor down-regulation are closely associated phenomena. These observations may be important in elucidating the phenomenon of SP-induced desensitization.
[Purpose] The general motor strategy for gait initiation is achieved by the difference
between the center of gravity and center of pressure; it be as bigger under speed
optimization. This study aimed to investigate the motor pattern in rapid gait initiation
under conditions of limited backward displacement of center of pressure. [Participants and
Methods] The participants were 30 healthy young males (mean age, 19.7 ± 1.0 years). They
performed a gait initiation task at three center of pressure start positions (anterior,
middle, and posterior) and two speed conditions (normal and rapid). The gait initiation
motion was measured using a video camera and motor pattern in the images was classified.
The center of pressure position was continuously monitored using a pressure distribution
measurement system. [Results] Forward tilt pattern was the most common under no limited
center of pressure control and normal speed. The backward tilt pattern was the most
preferred in the posterior position under limited center of pressure control and rapid
speed. Displacement of the center of pressure showed a significant decline when the center
of pressure start position was displaced backward. [Conclusion] The backward tilt pattern
is the most effective motor strategy to increase the forward speed of the center of
gravity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.