Abstract
The relative influence of circulating noradrenalin and sympathetic tonus on urethral pressure was investigated by intravenous administration of noradrenalin and clonidine. Raising circulating noradrenalin concentrations by noradrenalin infusion had only a relatively minor effect on urethral pressure, indicating that urethral pressure is not controlled by circulating noradrenalin. Besides depression of sympathetic tonus and urethral pressure, clonidine reduced striated anal sphincter activity.