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Completed

NCT Number: NCT02084797

V2 Receptor Effects on Fluid Regulation and Performance

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.

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Key information

Conditions

Electrolyte Imbalance Diabetes Insipidus Endocrine System Diseases Female Urogenital Diseases Female Urogenital Diseases and Pregnancy Complications Hypernatremia Hyponatremia Kidney Diseases Male Urogenital Diseases Metabolic Diseases Nutritional and Metabolic Diseases Pituitary Diseases Urogenital Diseases Urologic Diseases Water-Electrolyte Imbalance

Age range

18 year–60 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Oakland University

Rochester, Michigan, 48309, United States

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

V2R (Vasopressin 2 receptor)

Drug

All ten subjects were used as their own controls in this double-blind, randomized controlled trial assessing the effect of the V2R on sweat sodium concentration via use of a V2R blocker (antagonist), stimulator (agonist), against a placebo (drug naive state).

Other names: V2R antagonist: tolvaptan (30mg tablet), V2R agonist: desmopressin (0.2mg tablet)

Primary outcomes

  1. Sweat Sodium Concentration Obtained After the Steady-state Portion of the Trial

    Time frame: 4 study trials (4 weeks)

    Changes in sweat sodium concentration will parallel changes in urine sodium concentration with use of the V2R antagonist, agonist and placebo if the primary hypothesis is true (sweat sodium is regulated by the V2R, similar to how urine sodium is regulated by principle cells located within in the kidney collecting duct)

Secondary outcomes

  1. Urine Sodium Concentration After the Steady-state Portion of the Trial

    Time frame: 4 study trials (4 weeks)

    Changes in urine sodium concentration after use of the V2R antagonist, agonist and placebo interventions will verify whether or not pharmacologic activation or inhibition was successfully induced.

  2. Blood Sodium Concentration

    Time frame: 4 study trials (4 weeks)

    Measurement of blood sodium concentration will determine if normonatremia (blood sodium concentrations within the normal physiological range of 135-145mmol/L) were maintained throughout the trial with appropriate fluid intake during the V2R antagonist, agonist and placebo intervention trials.

  3. Saliva Sodium Concentration

    Time frame: 4 trials (4 weeks)

    Measurement of salivary sodium concentration will allow us to determine if the V2R antagonist, agonist and placebo interventions activate aquaporin-5 (AQP5) water channels that are also located in sweat glands. If the V2R acts on the sweat glands through AQP5, there should be parallel changes in sweat, urine and saliva sodium concentrations with each pharmaceutical intervention.

Other outcomes

  1. Body Weight

    Time frame: 4 trials (4 weeks)

    Changes in body weight during the V2R antagonist, agonist and placebo conditions will provide researchers with an additional measure of overall fluid balance (fluid in versus fluid out) as well as an estimate of overall sweat water losses.

  2. Core Temperature

    Time frame: 4 trials (4 weeks)

    Measurement of core temperature using an ingestible CorTemp sensor during the V2R antagonist, agonist and placebo trials will allow researchers to assess if fluid homeostasis and thermoregulation were intertwined in response to each pharmacological intervention.

  3. Thirst Rating

    Time frame: 4 trials (4 weeks)

    To determine if fluid intake behaviors were appropriately regulated in response to the V2R antagonist, agonist and placebo conditions during exercise.

  4. Sodium Palatability Ratings

    Time frame: 4 weeks (4 trials)

    To determine if sodium preference ratings were appropriately regulated in response to the V2R antagonist, agonist and placebo conditions during exercise.

  5. Performance

    Time frame: 4 trials (4 weeks)

    To determine if exercise performance, as determined by overall exercise time, was affected in response to the V2R antagonist, agonist and placebo conditions.

  6. Fluid Intake

    Time frame: 4 weeks (4 trials)

    To determine if fluid intake behaviors were appropriately regulated in response to the V2R antagonist, agonist and placebo conditions during exercise.

Sponsors and collaborators

Lead sponsor

Oakland University

Other

Collaborators

  • Georgetown University

Registry information

Official study title

Revisiting the Human Sweat Gland - Does Arginine Vasopressin Modulate Sweat Sodium Concentration Via the V2 Receptor?

Important dates

Study start
2011
Primary completion
2011
Study completion
2012
First posted
Mar 12, 2014
Registry last updated
May 12, 2016

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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