1. Blood pressure, heart rate and changes of plasma renin concentration (PRC) have been studied in nineteen patients with traumatic transection of the spinal cord, in relation to change of posture from supine to upright.
2. When supine, subjects with cervical-cord transection had a normal blood pressure, a low heart rate and a high plasma renin concentration. On change of posture to the vertical, orthostatic hypotension developed, heart rate rose and PRC increased. Orthostatic hypotension was not a feature with change of posture in patients with transection of the thoracic spinal cord and PRC rose to a much smaller extent.
3. It is concluded that release of renin on change of posture can occur in patients with spinal-cord transection. Release of renin in man does not depend therefore upon an intact autonomic nervous system, though it is possible that reflex sympathetic pathways in the isolated spinal cord may be involved.