Changes in kidney response to ADH under hypogravity: rat models and possible mechanisms

Area of Science:

• Physiology
• Space Medicine
• Endocrinology

Background:

• Astronauts and individuals on prolonged bed rest exhibit inadequate responses to antidiuretic hormone (ADH).
• Understanding the physiological mechanisms behind this impaired response is crucial for mitigating health risks associated with spaceflight and immobility.

Purpose of the Study:

• To investigate the potential causes of diminished ADH responsiveness in conditions mimicking spaceflight and prolonged bed rest.
• To elucidate the role of intrarenal osmotic gradients and ADH receptor function in altered ADH response.

Main Methods:

• Utilized Brattleboro rats (diabetes insipidus, DI; heterozygous, HZ) with varying ADH deficiencies.
• Included young Wistar rats unresponsive to ADH.
• Simulated conditions of hypogravitation and antiorthostasis (-60 degrees).

Main Results:

• Experimental models demonstrated impaired ADH response.
• Findings suggest alterations in intrarenal osmotic gradients are involved.
• Changes in the aggregate state of ADH receptors, linked to decreased blood ADH levels under hypogravitation, are implicated.

Conclusions:

• Reduced ADH blood levels during hypogravitation may lead to altered ADH receptor function.
• Changes in intrarenal osmotic gradients contribute to inadequate ADH response.
• These factors likely explain the impaired ADH response observed in cosmonauts during readaptation to Earth's gravity.