The Influence of Sex on the Osmoreceptor Modulation of Heat Loss Responses

Abstract

Females exhibit lower sudomotor response than males, which has been attributed to physiological differences between sexes. It is well accepted that non-thermal factors (i.e. baroreceptors and osmoreceptors) can influence thermoeffector responses. Even though there are sex-related differences in baroreceptor modulation of thermoeffector responses, it remains unknown if differences in osmoreceptor modulation could explain the lower sudomotor response in females. Therefore, we examined if there are sex-related differences in osmoreceptor modulation of sweating and cutaneous vascular conductance (CVC). A group of nine males and nine females were passively heated while in an isosmotic and hyperosmotic state. The onset and thermosensitivity of sweating and CVC were calculated and compared between groups and conditions. We show that the delay in onset of sweating and CVC is similar between sexes. However, thermosensitivity of sweating was lower in females than males. We conclude that hyperosmolality does not modulate the decreased sudomotor activity in females.