Plasma total homocysteine in Mexican rural and urban women fed typical model diets.

OBJECTIVE: The purpose of the present work was to determine the fasting plasma total homocysteine (tHcy) levels and the time-course response of tHcy concentrations after the consumption of urban and rural Mexican model diets in two groups of Mexican women from urban and rural areas. METHODS: Thirty-three adult women (age range = 18-49 y) were studied. Fifteen women were from a rural community in the state of Mexico. The other 18 were from cities and consumed diets that regularly included an important amount of animal foods. The study was designed as a two-period crossover study in which subjects consumed the model urban or rural diet in a 2-wk interval. Seven milliliters of venous blood was drawn before ingestion of experimental diets (basal) to measure total cholesterol, high-density lipoprotein cholesterol, triacylglycerol, tHcy, folate, vitamin B12, and methionine. Blood samples were then obtained 30, 60, 90, 180, and 240 min after the beginning of meal consumption. RESULTS: The rural and urban groups showed similar concentrations of tHcy 4 h after meal consumption and after fasting. However, the urban and rural groups had higher methionine plasma concentrations after the urban diet than after the rural diet. In contrast, there was no significant difference in methionine plasma levels between the rural and urban groups with each diet. Those women with low tHcy concentrations maintained those values over the study period, and those with high tHcy concentrations maintained those values. There was no significant difference in tHcy concentrations due to consumption of the two diets (P = 0.31) or the interaction between population and diet (P = 0.84). However, there was a significant difference in the concentration of tHcy between the rural (8.73 +/- 0.17 microM/L) and the urban (9.27 +/- 0.13 microM/L) populations (P = 0.01). In both groups, average tHcy concentration was in the normal range. In both populations, the nutrition status for folate and vitamin B12 was adequate, although plasma folate concentration was significantly lower in the rural population than in the urban population (P < 0.01). Plasma vitamin B12 concentrations were similar in both groups. No subject had low plasma vitamin B12. CONCLUSIONS: Plasma tHcy concentrations in rural and urban Mexican women were within the range considered adequate; however, urban women showed significant higher concentrations than did rural women independently of the consumed diet and the plasma methionine concentration. These results indicated that there is no short-term variation in plasma tHcy due to the consumption of rural or urban diets.

Reduction of Na(+),K(+)-ATPase activity in hippocampus of rats subjected to chemically induced hyperhomocysteinemia.

Hyperhomocysteinemia occurs in homocystinuria, an inherited metabolic disease clinically characterized by thromboembolic episodes and a variable degree of neurological dysfunction whose pathophysiology is poorly known. In this study, we induced elevated levels of homocysteine (Hcy) in blood (500 microM), comparable to those of human homocystinuria, and in brain (60 nmol/g wet tissue) of young rats by injecting subcutaneously homocysteine (0.3-0.6 micromol/g of body weight) twice a day at 8-hr intervals from the 6th to the 28th postpartum day. Controls received saline in the same volumes. Na(+),K(+)-ATPase and Mg(2+)-ATPase activities were determined in the hippocampus of treated Hcy- and saline-treated rats. Chronic administration of Hcy significantly decreased (40%) Na(+),K(+)-ATPase activity but did not alter Mg(2+)-ATPase activity. Considering that Na(+),K(+)-ATPase plays a crucial role in the central nervous system, our results suggest that the brain dysfunction found in homocystinuria may be related to the reduction of brain Na(+),K(+)-ATPase activity.