Clinical trial NCT02084797: V2 Receptor Effects on Fluid Regulation and Performance
Official title: Revisiting the Human Sweat Gland - Does Arginine Vasopressin Modulate Sweat Sodium Concentration Via the V2 Receptor?
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Electrolyte Imbalance
Hyponatremia
Hypernatremia
Keywords: arginine vasopressin
sweat sodium
V2 antagonist
running
Lead sponsor: Oakland University
Sponsor class: OTHER
Collaborators: name: Georgetown University
First posted: 2014-03-12
Enrollment: 10
Sex: ALL
Minimum age (years): 18
Maximum age (years): 60
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER

Brief summary: This primary aim of this study was to critically assess whether or not sweat water content and sodium concentration were acutely regulated by dynamic changes in antidiuretic hormone (arginine vasopressin or AVP) acting on the Vasopressin 2 receptor (V2R) during exercise. Secondary aims were to evaluate running performance and core temperature to further characterize the role of AVP in the coordinated balance of fluid and temperature homeostasis during exercise. The primary hypothesis was that activation of the V2R in sweat glands would result in water reabsorption and fluid conservation during endurance exercise.

Detailed description: Ten healthy habitual runners (\> 50km running per week) between 18-60 years of age participated in this double blind randomized control trial. Each subject presented to the exercise lab on four separate occasions. Trial 1 was a familiarization trial to determine each subject's maximal aerobic capacity and peak treadmill running speak (VO2 Peak test). Trials 2, 3 and 4 utilized the same exact protocol, differing only in pharmacological intervention. In a randomized, double-blind order (both participant and investigator blinded to the intervention), either a placebo pill, the V2 receptor antagonist tolvaptan (Samsca™, 30mg tablet), or the V2 receptor agonist desmopressin (DDAVP™, 0.2mg tablet) was ingested along with the CorTemp™ Core Temperature Sensor two hours before commencement of the Exercise Trial with 240mL of bottled water. The exercise protocol consisted of 60 minutes of treadmill running at 60% of peak speed (steady-state) followed by a performance test (the VO2 Peak test). Blood, saliva and urine, were collected before the exercise trial (baseline) and again after both the steady-state run and performance runs. Sweat was obtained from sweat patches after both the steady-state and performance runs. Core temperature, fluid intake, performance time, body weight, thirst and sodium palatability ratings were also assessed. Free access to water was allowed during the trial and all urine produced during the trial was measured and collected. The main outcome measure was sweat sodium concentration.

Eligibility criteria: Inclusion Criteria:

* Healthy (no acute or chronic medical conditions or regular prescription medication use), habitual (\>50km/week)
* Distance runners between the ages of 18-60 years.

Exclusion Criteria:

* Individuals with chronic medical problems which require regular prescription medication
* Runners with pre-existing kidney problems
* Unable to sense thirst
* Difficulty swallowing
* Gastrointestinal disorders
* History of fainting associated with blood draw.

Primary outcomes:
measure: Sweat Sodium Concentration Obtained After the Steady-state Portion of the Trial
timeFrame: 4 study trials (4 weeks)
Secondary outcomes:
measure: Urine Sodium Concentration After the Steady-state Portion of the Trial
timeFrame: 4 study trials (4 weeks)
measure: Blood Sodium Concentration
timeFrame: 4 study trials (4 weeks)
measure: Saliva Sodium Concentration
timeFrame: 4 trials (4 weeks)
Other outcomes:
measure: Body Weight
timeFrame: 4 trials (4 weeks)
measure: Core Temperature
timeFrame: 4 trials (4 weeks)
measure: Thirst Rating
timeFrame: 4 trials (4 weeks)
measure: Sodium Palatability Ratings
timeFrame: 4 weeks (4 trials)
measure: Performance
timeFrame: 4 trials (4 weeks)
measure: Fluid Intake
timeFrame: 4 weeks (4 trials)
Locations:
city: Rochester
country: United States
facility: Oakland University
state: Michigan
Study officials:
affiliation: Oakland University
name: Tamara D Hew-Butler, PhD
role: PRINCIPAL_INVESTIGATOR
affiliation: Georgetown University
name: Joseph G Verbalis, MD
role: STUDY_DIRECTOR
References:
citation: Hew-Butler T, Hummel J, Rider BC, Verbalis JG. Characterization of the effects of the vasopressin V2 receptor on sweating, fluid balance, and performance during exercise. Am J Physiol Regul Integr Comp Physiol. 2014 Aug 15;307(4):R366-75. doi: 10.1152/ajpregu.00120.2014. Epub 2014 Jun 18.