Sodium

Neuroscience

Plasma osmolality

Endocrinology

Stimulation

Vasopressin

Organic chemistry

Psychology

Thirst

Hypertonic saline

Internal medicine

Medicine

Chemistry

Saline

Current Developments in Nutrition

Examine potential sex differences in osmotically stimulated thirst. 60 healthy adults (30 female - measured in early follicular phase, age: 39 ± 8 y, weight: 78.2 ± 15.2 kg, body mass index: 26.9 ± 4.0 kg·m−2) were infused intravenously with 3% (HYPER) or 0.9% (ISO) NaCl for 120 min (0.1 ml·kg−1·min−1) in a counterbalanced, cross-over design. The same volume of saline was infused in both trials. Blood samples and thirst responses were collected prior to infusion and every 30 minutes. Plasma osmolality (POsm) and sodium (PNa) were measured. Thirst was assessed via a 180-mm visual analog scale consisting of a line with an anchor on the left side (0 mm, “not at all”) and a second anchor on the 125-mm mark with the label “extremely”. From 0 min to 120 min in the HYPER trial, PNa increased from 136 ± 2 mmol ·L−1 to 146.5 ± 3 mmol ·l−1 (P < 0.001). Similarly, POsm and thirst increased significantly from 286 ± 3 mmol·kg−1 to 305 ± 4 mmol·kg−1 (P < 0.001) and from 38 ± 29 mm to 88 ± 35 mm (P < 0.001), respectively. During the ISO trial, PNa (0 min: 135.9 ± 1.9; 120 min: 137.6 ± 1.6 mmol·L−1), POsm (0 min: 285 ± 4 mmol·kg−1; 120 min: 287 ± 3 mmol·kg−1), and thirst (0 min: 30 ± 27 mm; 120 min: 44 ± 32 mm) remained unchanged (P > 0.05). POsm at the end of the infusion did not differ between men and women for the HYPER (men: 306 ± 5 mmol·kg−1; women: 305 ± 3 mmol·kg−1) or ISO (men: 288 ± 3 mmol·kg−1; women: 288 ± 3 mmol·kg−1) trials. When thirst responses were split by sex women exhibited greater thirst (98 ± 27 mm) than men (77 ± 38 mm) at the end of the HYPER trial (P < 0.0001), but not at the end of the ISO trial (women: 43 ± 32 mm, men 44 ± 31 mm; P > 0.05). These data suggest that similar hypertonic stimulus may lead to greater thirst stimulation in women. This study was funded by Danone Research.

Osmotic Stimulation of Thirst in Men and Women (P15-017-19)