Activation of lumbar spinoreticular neurons by stimulation of muscle, cutaneous and sympathetic afferents.

Forty-four spinal neurons located mainly in laminae IV-VII of the L7 and S1 segments projected primarily contralaterally and to the lateral reticular nucleus. Muscle and cutaneous input was via group II and III afferents, whereas sympathetic input was via group III or IV afferents. Close-arterial injection of bradykinin and/or capsaicin excited most of the neurons so tested. These responses make these neurons likely candidates for the ascending pathway of the exercise pressor reflex.