Blood Pressure Adaptability and the Menstrual Cycle
To this point, the“hidden adaptability”of blood pressure has been seen from the
perspective of its dynamic variation in response to instantaneously changing
circumstances.
However, it is important to note that these changes in blood pressure are mostly
facilitated by the actions of several hormonal systems which regulate arterial lumen
and plasmafluid volume and which are more directly affected by environmental
changes and cognitive processes (see Laragh and Brenner 1995 ). There is a“hidden
adaptation” regarding one of these systems, the renin–angiotensin–aldosterone
system (RAAS) that occurs over the menstrual cycle in women.
Continuous circadian allostatic variation in the hormones of the RAAS, plasma
renin activity (PRA), angiotensin II, and aldosterone help regulatefluid volume and
electrolyte balance through their influence on renal bloodflow and glomerular
filtration in the kidney (see for example, Sealey and Laragh 1995 ; Stachenfeld et al.
1999 ; Chidambaram et al. 2002 ; Pechere-Bertschi and Burnier 2004 ). Specifically,
Fig. 8.6 Exemplar effects of posture (sitting, standing), location (work, home, elsewhere), and
emotional state (happy, angry, anxious) on daily blood pressure (data from James et al. 1988 ).
Defined as mmHg from the 24-h mean and is based on the assumption that the measure of
dispersion around the 24-h mean (standard deviation) is 10 (modified from James 2013 )
8 Continuous Blood Pressure Variation: Hidden Adaptability 157