V2 Receptor Effects on Fluid Regulation and Performance

Oakland University

Status: Completed

Conditions: Hypernatremia; Hyponatremia; Electrolyte Imbalance

Treatments: Drug: V2R (Vasopressin 2 receptor)

Study type: Interventional

Funder types: Other

Identifiers

NCT02084797

RAM#4713

Details and patient eligibility

About

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.

Full 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.

Enrollment: 10 patients

Sex: All

Ages: 18 to 60 years old

Volunteers: Accepts Healthy Volunteers

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.

Trial design

10 participants in 1 patient group

all study participants

Experimental group

Description:

All study participants received all interventions. V2R Antagonist: 30mg Tolvaptan tablet ingested 2 hours before exercise. V2R agonist: 0.2mg DDAVP tablet ingested 2 hours before exercise Placebo

Treatment:

Drug: V2R (Vasopressin 2 receptor)