This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This protocol will examine whether increased potassium intake will normalize dipping status and renal function reserve in high risk, non-dipper subjects. Systemic arterial hypertension (high blood pressure) and end-stage renal disease (ESRD) negatively impact public health in the United States, producing staggering financial costs and enhanced morbidity and mortality in the population. The use of 24-hour blood pressure monitoring to document blood pressure loads and circadian (night) patterns in blood pressure are being widely studied. The use of a 24-hour blood pressure monitoring system has allowed for classification of subjects by daytime, nighttime, and change from day to nighttime status for systolic, diastolic, and mean arterial pressure. Although there is some variability in the definition of dipping status - the ability to decrease blood pressure during nighttime compared to daytime- the most common definition is a decrease of 10%. Non-dipper status- the failure of blood pressure to decrease at night- has been shown to be more common in patients with chronic renal (kidney) failure, urinary protein excretion, greater left ventricular wall thickness, greater forearm vascular resistance, and increased serum cholesterol. In hypertensive patients (patients with high blood pressure) the progression to renal failure is usually slow. Therefore, identifying an early marker of impending renal function decline is necessary to select a group of patients at risk for renal failure. Current evidence suggests that potassium plays an active role in cardiovascular protection. In animal studies, augmenting potassium plasma concentration diminishes the formation of other cardiovascular factors that are incriminated in vascular wall injury. Thus, potassium supplementation can be proposed to improve cell function, which will improve dipping status and consequently renal function. This is a randomized blinded placebo controlled study to evaluate the response to oral potassium supplementation on dipping status and renal function reserve. All subject visits will take place in the GCRC. Following informed consent, a screening history and physical and laboratory work will be performed. Subjects who qualify for the study will return to the GCRC for baseline measurements. Subjects who are non-dipper/non-dipper or dipper/dipper on the first two blood pressure monitorings will be randomly assigned to start either placebo or postassium supplementation for an 8-week period. After 4 weeks, the subjects will return to the GCRC for an admission which includes a 24-hr urine and potassium level. After the 8 week study period, the subjects will return for a GCRC admission which includes other laboratory and clinical measurements to determine renal function status and dipping status. All data will be recorded and analyzed to determine if potassium supplementation improves dipping status
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