Experimental uninephrectomy associates with less parasympathetic modulation of heart rate and facilitates sodium-dependent arterial hypertension

BackgroundBlood pressure is known to be increased in kidney donors following living-donor kidney transplantation. However, the physiological underpinnings of the blood-pressure increase following uninephrectomy remain unclear. We hypothesized that changes in sympathetic tone or in parasympathetic modulation of sinus node function are involved in the blood-pressure increase following experimental kidney-mass reduction. MethodsC57BL6N mice (6 to 11 per group) subjected to sham surgery (controls) or uninephrectomy with or without a one-week course of sodium chloride-enriched, taurine-deficient diet were studied. Uninephrectomized mice treated with a subcutaneous infusion of angiotensin-II over a period of one week were positive controls. A transfemoral aortic catheter with telemetry unit was implanted, readings of heart-rate and blood-pressure were recorded. Powerspectral analysis of heart rate and systolic blood pressure was performed to gain surrogate parameters of sympathetictone and parasympathetic modulation of sinus node function. Baroreflex sensitivity of heart rate was determined from awake, unrestrained mice using spontaneous baroreflex gain technique. ResultsSystolic arterial blood pressure, heart rate and baroreflex sensitivity were not different in uninephrectomized mice when compared to controls. Parasympathetic modulation of sinus node function was less in uninephrectomized mice in comparison to controls. Uninephrectomized mice of the high-angiotensin-II model or of the high-salt and taurine-deficiency model had an increased systolic arterial blood pressure. ConclusionsUninephrectomy associated with less parasympathetic modulation of sinus node function. The combination of uninephrectomy, taurine-deficiency and high-salt intake led to arterial hypertension.

Automated summary

In this study, the physiological mechanisms underlying the increase in blood pressure following partial kidney removal were investigated. The results showed that partial kidney removal was associated with reduced parasympathetic modulation of sinus node function, and the combination of taurine deficiency and high salt intake further led to arterial hypertension.