CHAPTER
ONE
INTRODUCTION
Preeclampsia is the most common medical
complication of pregnancy. It is also known as pregnancy-induced hypertension
(PIH) or toxemia and is one of the leading causes of maternal and perinatal
mortality throughout the world (Chesley, 1978). 790 maternal deaths per 100,000
live births have been reported due to preeclampsia (Wagner, 2004). Preeclampsia is characterized by development
of high blood pressure (hypertension) and proteinuria after 20 weeks of
gestation and affects about 5-8% of all pregnancies (Ray, 2006). Numerous
studies have described the complex dependence of electrolyte concentrations in
normotensive and preeclamptic pregnant women. Results of some of the important
studies are contradictory. The electrolytes like sodium and potassium contribute
significantly in the functioning of the vascular smooth muscles and may play an
important role in the aetiopathogenesis of hypertension which is evident from
the use of dietary sodium restriction as one of the prime treatments of high
blood pressure.
Hypertension results primarily from the
interplay of internal derangements (primarily in the kidney) and the external
environment. Sodium, the main extracellular cation, has long been considered
the pivotal environmental factor in the disorder. Numerous studies show an
adverse effect of a surfeit of sodium on arterial pressure (O’Shaughnessy KM,
Karet, 2004; Iwamoto and Kita, 2006). By contrast, potassium, the main
intracellular cation, has usually been viewed as a minor factor in the
pathogenesis of hypertension. However, abundant evidences indicates that
potassium deficit has a critical role in hypertension and its cardiovascular
sequelae (Whelton, 2003; National Academies Press, 2005). In a clinical study,
a diet low in potassium (10 to 16 mmol per day) coupled with the participants’
usual sodium intake (120 to 200 mmol per day) caused sodium retention and an
elevation of blood pressure; on average, systolic pressure increased by 6 mm Hg
and diastolic pressure by 4 mm Hg in normotensive subjects, and systolic
pressure increased by 7 mm Hg and diastolic pressure by 6 mm Hg in hypertensive
subjects (Krishna and Kapoor, 1991). Studies have shown that increasing the
potassium intake of hypertensive rats that were fed on high sodium diets
lowered blood pressure, reduced the incidence of stroke and stroke-related
death and prevented cardiac hypertrophy, mesenteric vascular damage, and renal
injury.
1.2 Purpose of the study
The main purpose of the study is to understand
the role of electrolytes (Na+, K+ and Cl) in the
pathogenesis of preeclampsia.