Effects of Saline Loading on the Renin, Erythropoietin, and Blood Pressure Responses to Canine Renal Allotransplantation

Abstract

Serial determinations of plasma erythropoietin and renin activities and mean arterial blood pressure were done in five dogs before and after renal allotransplantation. Throughout the experiment, the animals were given 154 mEq of NaCl per day, starting 1 week before transplantation. No immunosuppressive therapy was given. Onset of immunological rejection was determined by daily measurement of endogenous creatinine clearance. Arterial pressure and plasma erythropoietin concentration increased markedly at the time of rejection, with the curves for the two variables closely paralleling each odier in all animals. Serial determinations of plasma volume done in two of the dogs did not show any significant change at the time when hypertension appeared. Plasma renin activities remained very low throughout the experiments, indicating that even with the vascular lesions of rejection renin release is still subject to normal control mechanisms. It is concluded that elevated plasma renin activity is not an essential causal factor of the hypertension which occurs with renal allograft rejection. Since it is possible to suppress renin release without substantially inhibiting erythropoietin release, different stimuli appear to cause release of these substances.