The Effect of High and Low Sodium Intake on Urinary Aquaporin-2 in Autosomal Dominant Polycystic Kidney Disease

Polycystic Kidney, Autosomal Dominant Clinical Trial

Official title:

The Effect of High and Low Sodium Intake on Urinary Aquaporin-2 in Autosomal Dominant Polycystic Kidney Disease, During Basal Conditions and After Hypertonic Saline Infusion.

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00410007
• Other study ID #: med.res.hos.2006.cc.03
• Status: Completed
• Phase: N/A
• First received: December 10, 2006
• Last updated: March 16, 2018
• Start date: October 2006
• Est. completion date: November 2011

Study information

• Verified date: March 2018
• Source: Regional Hospital Holstebro
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

The aim of the study is to test the following hypotheses:

1. that the function and/or regulation of AQP2 and /or ENaC in the principal cells is abnormal in autosomal dominant polycystic kidney disease.

2. if an abnormal function of the principal cells is present in autosomal dominant polycystic kidney disease, this will become more pronounced at high and low sodium intake.

Description:

Recruitment:

The patients with ADPKD are recruited from the Outpatient Nephrology Clinic of the Department of Medicine, Holstebro Hospital (Holstebro, Denmark). The control subjects are recruited by advertising in public institutions and private companies.

Number of Subjects:

A difference in u-AQP2CR of 40 ng/mmol is considered the minimal relevant difference. A sample size of 10 subjects, who can be evaluated, has 80% power to detect this difference assuming a level of significance of 5% and an SD of 30 ng/mmol. Because a few subjects are expected to drop out, 14-15 subjects will be included in each group.

Experimental Procedure Before the Study Day:

Five days before the study day, the subjects collect a standardized, HS (300 mmol sodium/day/17.5 g salt/day) or LS (30 mmol sodium/day/1.8 g salt/day), 4-day diet from the hospital kitchen. Depending on the individually estimated energy requirement, the participants are given either a diet of 8,000 or 11,000 kJ/day. The energy distribution is 55% carbohydrates, 15% proteins, and 30% lipids. The 4-day diet is started the following morning. The fluid intake is also standardized during the 4 days. The subjects are asked to drink exactly 250 ml/1,000 kJ/day and to abstain from coffee, tea, and alcoholic beverages. The subjects are instructed to keep their physical activity unchanged during the two experiments and to abstain from hard training. The subjects have to collect their urine for 24 h the day before the study day.

Experimental Procedure on the Study Day:

On the study day, the subjects are asked to drink 175 ml of water every 30 min from 7:00 AM. The subjects arrive at the department at 8:00 AM. Peripheral iv lines are inserted into the antecubital veins of both forearms, one for infusion of 51Cr-EDTA and hypertonic saline, and one for withdrawal of blood samples. The subjects will be kept in the supine position from 8:00 AM to 1:30 PM except during voiding, which will take place in the sitting or standing position. At 8:30 AM, a priming dose of 51Cr-EDTA is administered, followed by sustained infusion. After 60 min of equilibration, the study will continue with five clearance periods, the first two of 30-min duration (P1-P2), the last three of 60-min duration (P3-P5). The first two clearance periods are baseline periods. At 10:30 AM, 7 ml/kg of 3% saline is given over 30 min. Blood pressure and heart rate are measured every 30 min from 9:30 AM to 1:30 PM. Urine is collected in each clearance period and analyzed for sodium, osmolality, u-AQP2, u-ENaC-betaCR, u-cAMP, u-PGE2, and 51CrEDTA. Blood samples will be drawn every 30 min from 9:30 AM to 10:30 AM and every hour from 11:30 AM to 1:30 PM, and will be analyzed for sodium, osmolality, and 51Cr-EDTA. In addition, analysis of p-AVP, p-Renin, p-ANG II, p-Aldo, p-ANP, and p-BNP will be performed from blood samples drawn at 10:30 AM, 11:30 AM, 12:30 PM, and 1:30 PM.

Statistics:

Statistical analyses will be performed using SPSS version 15 (SPSS, Chicago, IL). Single baseline values are obtained by taking the weighted average of the measurements from the two baseline periods. The baseline values of the two groups will be compared by Student's t-test. The baseline values during HS and LS intake will be compared by paired samples t-tests. The investigators will use the "General Linear Model Repeated Measures" procedure in SPSS with time as the within-subject factor and group as the between-subject factor to compare the effect variables in patients and controls. The changes in response to the hypertonic saline infusion in each group will be analyzed with the General Linear Model Repeated Measures procedure with time as the within-subject factor and paired samples t-tests with Bonferroni correction as post hoc tests. P values Recruitment The patients with ADPKD will be recruited from the Outpatient Nephrology Clinic of the Department of Medicine, Holstebro Hospital (Holstebro, Denmark). The control subjects will be recruited by advertising in public institutions and private companies.

Number of Subjects A difference in u-AQP2CR of 40 ng/mmol is considered the minimal relevant difference. A sample size of 10 subjects, who could be evaluated, has 80% power to detect this difference assuming a level of significance of 5% and an SD of 30 ng/mmol. Because a few subjects are expected to drop out, 14-15 subjects will be included in each group.

Experimental Procedure Before the Study Day Five days before the study day, the subjects will collect a standardized, HS (300 mmol sodium/day/17.5 g salt/day) or LS (30 mmol sodium/day/1.8 g salt/day), 4-day diet from the hospital kitchen. Depending on the individually estimated energy requirement, the participants will be given either a diet of 8,000 or 11,000 kJ/day. The energy distribution will be 55% carbohydrates, 15% proteins, and 30% lipids. The 4-day diet will start the following morning. The fluid intake is also standardized during the 4 days. The subjects are asked to drink exactly 250 ml/1,000 kJ/day and to abstain from coffee, tea, and alcoholic beverages. The subjects will be instructed to keep their physical activity unchanged during the two experiments and to abstain from hard training. The subjects have to collect their urine for 24 h the day before the study day.

Experimental Procedure on the Study Day On the study day, the subjects are asked to drink 175 ml of water every 30 min from 7:00 AM. The subjects arrive at the department at 8:00 AM. Peripheral iv lines will be inserted into the antecubital veins of both forearms, one for infusion of 51Cr-EDTA and hypertonic saline, and one for withdrawal of blood samples. The subjects will be kept in the supine position from 8:00 AM to 1:30 PM except during voiding, which will take place in the sitting or standing position. At 8:30 AM, a priming dose of 51Cr-EDTA is administered, followed by sustained infusion. After 60 min of equilibration, the study will continue with five clearance periods, the first two of 30-min duration (P1-P2), the last three of 60-min duration (P3-P5). The first two clearance periods are baseline periods. At 10:30 AM, 7 ml/kg of 3% saline is given over 30 min. Blood pressure and heart rate will be measured every 30 min from 9:30 AM to 1:30 PM. Urine is collected in each clearance period and analyzed for sodium, osmolality, u-AQP2, u-ENaC-betaCR, u-cAMP, u-PGE2, and 51CrEDTA. Blood samples will be drawn every 30 min from 9:30 AM to 10:30 AM and every hour from 11:30 AM to 1:30 PM, and will be analyzed for sodium, osmolality, and 51Cr-EDTA. In addition, analysis of p-AVP, p-Renin, p-ANG II, p-Aldo, p-ANP, and p-BNP will be performed from blood samples drawn at 10:30 AM, 11:30 AM, 12:30 PM, and 1:30 PM.

Statistics Statistical analyses will be performed using SPSS version 15 (SPSS, Chicago, IL). Single baseline values are obtained by taking the weighted average of the measurements from the two baseline periods. The baseline values of the two groups will be compared by Student's t-test. The baseline values during HS and LS intake will be compared by paired samples t-tests. The investigators will use the "General Linear Model Repeated Measures" procedure in SPSS with time as the within-subject factor and group as the between-subject factor to compare the effect variables in patients and controls. The changes in response to the hypertonic saline infusion in each group will be analyzed with the General Linear Model Repeated Measures procedure with time as the within-subject factor and paired samples t-tests with Bonferroni correction as post hoc tests. P values ≤0.05 will be considered significant.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 29
• Est. completion date: November 2011
• Est. primary completion date: October 2010
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 65 Years

Eligibility

Inclusion Criteria:

• Caucasian men and women

• age 18-65 years

• BMI between 18,5-30,0 kg/m2

• ADPKD, diagnosed by the following findings on ultra scan:

• for patients without ADPKD family history: > 5 bilateral cysts

• for patients with ADPKD family history: < 30 years: 2 cysts (unilateral or bilateral) 30-60 years: 2 or more bilateral cysts > 60 years: 4 or more bilateral cysts

• Kidney function: stadium 1-4.

Exclusion Criteria:

• Other kidney disease

• Anamnestic or clinical signs of acute myocardial infarction, atrial fibrillation, heart valve disease or chronic heart failure

• Anamnestic or clinical signs of disease in lungs, liver,endocrine organs or brain or neoplastic disease

• Family history of rupture of intracerebral aneurisms

• Alcohol or drug abuse

• Smoking

• Medical treatment arat form antihypertensives and oral anticonceptives

• Pregnancy or breastfeeding

Related Conditions & MeSH terms

• Kidney Diseases
• Polycystic Kidney Diseases
• Polycystic Kidney, Autosomal Dominant

Intervention

Behavioral:
• High Sodium Diet
250-350 mmol
• Low Sodium Diet
25-35 mmol
• Hypertonic saline infusion
7 ml/ kg of 3% saline were given over 30 minutes.

Locations

Country	Name	City	State
Denmark	Department of Medical Research, Holstebro Hospital	Holstebro

Sponsors (1)

Lead Sponsor	Collaborator
Carolina Cannillo

Country where clinical trial is conducted

Denmark, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	u-AQP-2CR	Urinary Aquaporin-2 corrected for creatinine	Before and after hypertonic saline infusion after 4 days on high and low sodium diet, respectively.
Secondary	u-ENaC (beta)CR	Urinary ENaC (beta) corrected for creatinine	Before and after hypertonic saline infusion after 4 days on high and low sodium diet, respectively.
Secondary	FENa	fractional sodium excretion	Before and after hypertonic saline infusion after 4 days on high and low sodium diet, respectively.
Secondary	CH2O	Free water excretion	Before and after hypertonic saline infusion after 4 days on high and low sodium diet, respectively.
Secondary	u-cAMP	urinary excretion of cAMP	Before and after hypertonic saline infusion after 4 days on high and low sodium diet, respectively.
Secondary	uPGE-2	urinary excretion of PGE-2	Before and after hypertonic saline infusion after 4 days on high and low sodium diet, respectively.
Secondary	GFR	glomerular filtration rate	Before and after hypertonic saline infusion after 4 days on high and low sodium diet, respectively.
Secondary	p-vasopressin	plasma concentration of vasopressin	Before and after hypertonic saline infusion after 4 days on high and low sodium diet, respectively.
Secondary	p-aldosterone.	plasma concentration of aldosterone	Before and after hypertonic saline infusion after 4 days on high and low sodium diet, respectively.