Aspartic acid administered neonatally affects ventilation of male and female rats differently

In this study ventilation was evaluated in 12-mo-old male and female rats who had received large doses of aspartic acid neonatally. Rats of both sexes treated with aspartic acid were obese, stunted, and exhibited hypogonadism. Although metabolic rates of the aspartic acid-treated rats were not different compared with sex-matched controls, ventilatory patterns were different. Aspartic acid-treated females breathed with a smaller tidal volume (VT), higher frequency (f), and similar minute ventilation (VE) compared with control females. This pattern is commonly observed in many patients who are obese. The aspartic acid-treated females responded to hypercapnic and hypoxic challenges by increasing f more than VT. Tissue pocket gases (PCO2 and PO2) of aspartic acid-treated females were normal. In contrast, aspartic acid-treated males hypoventilated compared with control males. Tissue pocket gas values suggested that aspartic acid-treated males were hypoxemic and hypercapnic. Moreover, the response of aspartic acid-treated males to hypercapnia was parallel to but was less than that of control male rats. The ventilatory response of aspartic acid-treated male rats to hypoxia was blunted. This study has shown that neonatal administration of aspartic acid causes a decreased ventilation and blunted response to hypoxia in adult male but not female rats.