Regulation of Arterial Pressure in the Anephric State

Three anephric patients were studied during sequential periods of normal hydration and overhydration. The increase in arterial pressure caused by the overhydration (+7% of body weight) was associated with an increase in peripheral resistance (+21.1%, P < 0.01). The elevation of peripheral resistance was preceded by an increased cardiac output (+22.3%, P < 0.02) which then fell part way to control levels (+13.2%, P < 0.05). Return to normal hydration resulted in return of all variables to control levels. The fall in peripheral resistance was preceded by a transient fall in cardiac output to below control levels (—5.6%, not significant). With both normal and elevated pressures, plasma renin activity levels were low, and sensitivity to angiotensin infusion was greater than normal. Long-term autoregulation of blood flow is suggested as an important factor in the observed sequence of events.