[Substance P and microcirculation during stress]

The experiments have been made on rats with the use of animals' immobilization on the back during 1 or 24 h as a stressor. Intravital study of the microcirculation in the rat mesentery has shown that P substance in a concentration of 7 X 10(-8) M aggravated the disturbances caused by the immobilization, while antiserum to P substance with an activity of 150 ng SP/equiv. normalized the microcirculation. The action of P substance and antiserum was similar as regards disturbances of vascular permeability for colloid carbon particles. It is concluded that P substance participates in the mechanisms of microcirculatory and vascular permeability disturbances during stress.