Adrenomedullin and galanin responses to orthostasis in older persons

Neuroendocrine responses to orthostasis may be critical in the maintenance of mean arterial pressure in healthy individuals. A greater reduction in orthostatic tolerance with age may relate to modulation of hormonal responses such as adrenomedullin and galanin. Thus, we investigated (i) whether adrenomedullin and galanin concentrations increase during orthostatic challenge in older subjects, (ii) whether adrenomedullin and galanin concentrations are higher in older females compared with older males when seated and during orthostatic challenge, and (iii) whether postural changes in plasma concentrations of galanin are correlated with levels of adrenomedullin in either older females or males.

Subjects (n = 18; 12 ♀; 55-80 years old) performed a sit-to-stand test in a 25°C sensory-minimised environment, with blood samples collected after 4 min of being seated and then when standing. Plasma adrenomedullin and galanin concentrations were determined.

Baseline plasma concentration of adrenomedullin (5·35 ± 0·74 (n = 12, females) vs. 7·40 ± 1·06 pg/mL (n = 5, males)) and galanin (64·07 ± 9·05 vs. 98·99 ± 16·90 pg/mL, respectively) did not significantly differ between genders. Furthermore, plasma adrenomedullin and galanin concentrations were not significantly affected by adoption of the upright posture in either gender and were not correlated in females or males.

Adrenomedullin and galanin concentrations were similar between genders and did not change following adoption of the standing posture. To further clarify the roles, these hormones play in orthostatic intolerance, adrenomedullin and galanin concentrations should be assessed in participants who show presyncopal symptoms during an orthostatic challenge.