The variations in small vascular wall function during the menstrual cycle in young healthy women.

It is known from the literature that there is a cycle dependent variation of
insulin sensitivity in healthy women with an ovulatoiry menstrual cycle.
Moreover, insulin sensitivity is assiocated with microvascular function. This
suggest that the microvasculair function is also cycle dependent. Williams et
al. showed indeed that the microvascular function is different in several
stages of the cycle. However, an other study didn't find a cycle dependent
variation in the microcirculation. In conclusion there are conflicting data and
therefore we designed the current study. Moreover, we use an unique technique
developed in the VU medical centre for the assesment of the microcirculatory
function. This technique is never done to determine cycle dependent function of
the microcirculation. The measurements obtained in the current study are very
important for the intrepretation of cardiovascular data.

Motivation of the used thechniques:
The microscoop is until now only used in the VU medical centre. The big
advantage is that it is non-invasief. The iontoforeses is done before by
Williams et al and Clifton et al but they had conflicting results. In the
current study we will use both techniques to determine if there is a cycle
dependent variation in the function of the microcirculation.

Discussion:
Despite of the conflicting results found by Williams et al and Clifton et al
(see above), we think that there is a cycle dependent variation in the
microcirculatory function. It is known that te insulin sensitivity has a cycle
dependent variation in healthy women. Moreover, menopausal women have a lower
risk of cardiovascular diseases compared to pre-menopausal women. The
explenation for this migth be that pre-menopausal women have an ovulatory
cycle, where hormones as estrogen and progestagen are produced. These hormones
can influence the vascular function.

Is there a cycle-dependent variation of the microvascular function in healthy
women.

Each subject was studied at three points during the menstrual
cycle,corresponding to early follicular (EF; day 3 ± 2), late follicular (LF;
day 12± 2) and luteal phase (L; day 20 ±
3).
The following measurements are performed
- Microvascular function, i.e. capillary function and iontophoresis (Ach, SNP
and insulin)
- Vasomotion
- Blood pressure and heart rate.
- hormones in serum
All subjects will come to the clinic after a 10-h overnight fast. All
experiments will be conducted in a quiet, temperature-controlled (23,4 ± 0,4
ºC) room. The first measurement will start after 30 minutes of acclimatization
with the subjects in supine position and the investigated hand at heart level.

All subjects will come to the clinic after a 10-h overnight fast, sit on a
chair 3-4 hours and a venapuntion, which is invasive, have to be performed at
each visit ( in total three times). The vascular measurement have no risks or
benefits.