Transporte eritrocitário da L-arginina pelos sistemas y+ e y+L na hipertensão arterial sistêmica, gestação normal e com distúrbios hipertensivos gestacionais

摘要

L-arginine is the precursor of nitric oxide - a potent endogenous vasodilator. This amino acid is transported via two membrane transport systems: y+ and y+L. Total L-arginine erythrocyte maximal capacity is increased in preeclampsia syndrome, especially in hypertensive patients with superimposed preeclampsia. The hypothesis of the present study is that erythrocyte L-arginine transport is associated with hypertension. The aim was to evaluate the activity of y+ and y+L erythrocyte membrane transport systems of L-arginine, in normotensive and hypertensive women, and women with and without the hypertensive disorders of pregnancy. Sample was composed by 137 women divided into followed groups: 39 with preeclampsia (PE), 8 with superimposed preeclampsia (SPE), 14 with gestational hypertension (GH), 10 with chronic hypertension (CH), 28 pregnant controls (CP), 20 non-pregnant hypertensive (HAS) and 18 non-pregnant normotensive women (N). L-arginine erythrocyte uptake was measured using 14C as a marker, and N-ethylmaleimide as y+ transport system inhibitor to obtain the function of two transport systems separately. The results were submitted to Michaelis-Menten equation to determine the maximal capacity of transport (Vmax) and half saturation constant (km). Results showed no alteration in total and y+L Vmax. The maximal capacity of transport via y+ system was lower in PE, GH and CP in comparision with normotensive non-pregnant. Half saturation constant (km) had no difference between groups.