Familial nephrogenic syndrome of inappropriate antidiuresis: dissociation between aquaporin-2 and vasopressin excretion.

Context: Nephrogenic syndrome of inappropriate antidiuresis (NSIAD), the X-linked disease resulting from activating mutation of the vasopressin V2 receptor gene (AVPR2), is a recently described condition causative of episodes of hyponatremia in boys and male and female adults.

Objective: The objective of the study was the pathophysiological characterization of NSIAD.

Design: A family with NSIAD was identified and investigated for hyponatremic episodes and degrees of urine dilution defects.

Skin aquaporins: function in hydration, wound healing, and skin epidermis homeostasis.

Several aquaporins (AQPs) are expressed in mammalian skin. Some are directly involved in water transport, such as AQP5, which is involved in sweat secretion. In contrast, the physiological role of skin aquaglyceroporins, which permeate both water and glycerol, appears more and more complex.

Hydrating skin by stimulating biosynthesis of aquaporins.

Aquaporins (AQPs) are proteins that facilitate the transport of water across cell membranes. AQP3 expression is related to the expressions of other epidermal proteins involved in water maintenance (ie, CD44, claudin-1, and filaggrin). The expressions of AQP3 water channels are strongly affected by age and chronic sun exposure, and a defective osmotic equilibrium could occur in the epidermis, which would account for the skin dryness observed in older people and skin areas most exposed to sunlight.