Arginine production & nitric oxide synthesis in pregnancy, a study in Jamaican, American and Indian women

Abstract

Arginine (arg) supply is critical for a successful pregnancy because of its roles in protein, nitric oxide (NO) and creatine syntheses and in cell growth and differentiation. NO is especially important for vascular expansion in pregnancy and a deficiency of arg supply could underlie the high prevalence of low birth weight (LBW) neonates in Indian women and in adolescent girls. Stable isotope tracers were used to measure arg flux and NO synthesis in pregnant American, Indian and Jamaican women and teenagers. Gestation Jamaica India United States Weeks Adult N=8 Teen N=8 Norm. BMI N=10 Low BMI N=10 Adult N=6 Arg Flux (μmol/kg/h) 13 108±6a 107±6a 50±2b 63±3b 20 108±5a 28 114±12a 82±7a 45±2b 50±2b 36–39 82±3 Post‐partum 73±6 Values are Mean±SEM; versus postpartum value, P<0.01 lower than Jamaican and American values, P<0.01 Except for normal BMI Indian women, NO synthesis was not different among groups at trimesters 1 and 3. Pregnant Indian women produced arg at a slower rate compared to all others. This slower arg flux was associated with slower NO synthesis in normal BMI, but not in low BMI Indian women. There were significant correlations between birth weight and arg flux at trimester 1 (r=0.54, P<0.01) and trimester 3 (r= 0.53, P<0.01), indicating a strong association between decreased arg flux and LBW. Not surprisingly, the Indian women delivered 45% LBW babies compared to 19% for Jamaicans.Grant Funding Source: USDA/ARS