Influence of season on plasma antidiuretic hormone, angiotensin II, aldosterone and plasma renin activity in young volunteers

Abstract

We investigated seasonal changes in hormonal and thermoregulatory responses. Eight volunteers were subjected to the experiment at four times of the year: around the vernal and autumnal equinoxes, and at the summer and winter solstices at latitude 35 degrees N. Plasma antidiuretic hormone (ADH), angiotensin II (ANG II), aldosterone (ALD) and plasma renin activity (PRA) were analyzed before and after water immersion. Seasonal changes in thermoregulatory responses were assessed by measuring core temperature and sweat rate during immersion of the leg in hot water (at 42 degrees C) for 30 min in a room maintained at 26 degrees C. The concentration of plasma ADH and ALD before water immersion was significantly higher in summer than in other seasons. The concentrations of ANG II and PRA did not show seasonal variations. Changes in tympanic temperature during water immersion showed significant differences between seasons, and were higher in winter than in other seasons. The sweat rate was significantly higher in summer than in other seasons. In summary, ADH and ALD concentrations displayed a seasonal rhythm with marked elevation in summer; this may be a compensative mechanism to prevent dehydration from increased sweat loss during summer due to heat acclimatization.

Effects of aging on thermoregulatory responses and hormonal changes in humans during the four seasons in Japan

“…However, in our study, ADH secretion in the elderly was not significantly different among seasons, and, the ADH level was higher in summer than in winter in the young. In summer, the environmental temperature is higher than in winter, which might induce heat acclimatization, with elevation of concentrations of ADH due to a compensatory mechanism to prevent dehydration from increased sweat loss during summer (Kanikowska et al 2010).…”

“…Each subject, wearing a Tshirt and shorts, immersed his lower legs in warm water at 40°C for 30 min in a sitting position in a climatic chamber set at 26°C and 50% relative humidity. Immersion of the legs in hot water has been established as a standard method to enhance sweating and body temperature (Kanikowska et al 2010). Core (tympanic) temperature and sweat rate at chest were recorded continuously.…”

The association of remotely-sensed outdoor temperature with blood pressure levels in REGARDS: a cross-sectional study of a large, national cohort of African-American and white participants

“…We also examined temperature fluctuation and variability to determine whether the body's physiological adjustment and acclimatization, or possible behavioral changes (such as clothing choices, time spent outdoors) could have been involved in a participant's response to temperature [15,16]. Temperature fluctuations were calculated as the range of temperatures on the day of the in-home visit (same-day maximum minus same-day minimum), 2-day change (the difference between the same and previous days' maximum or minimum), or as the weekly variance of the daily maximum or minimum temperatures (week previous to the in-home visit, inclusive).…”

Role of Mast Cells in the Control of Aldosterone Secretion

“…Globally, all these data indicate that adrenal mast cells promote mineralocorticoid secretion in concert with circulating RAS. The observation that human plasma aldosterone reaches maximum levels in summer while plasma Ang II show no seasonal variations [39] (▶Fig. 2b), suggests that, in humans as in amphibians, mast cells might play a role in control of mineralocorticoid production to optimally adapt the hydromineral homeostasis to sweating due to warm environment temperatures.…”

“…b Circannual variation of plasma aldosterone levels in the toad Bufo japonicas formosus (data from[98]). c Seasonal variations of plasma aldosterone and angiotensin II (Ang II) concentrations in human (data from[39]).…”