You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

High salt diets during pregnancy affected fetal and offspring renal renin-angiotensin system. Intrauterine environments are linked to fetal renal development and postnatal health. Influence of salt diets during pregnancy on renal functions and renin-angiotensin system (RAS) were determined in the ovine fetus and offspring. Pregnant ewes were fed high-salt diet (HSD) or normal-salt diet (NSD) for two months during middle-later gestation. Fetal renal functions, plasma hormones, mRNA and protein expressions of the key elements of renal RAS were measured in the fetus and offspring. Fetal renal excretion of sodium was increased while urine volume decreased in HSD group. Fetal blood urea nitrogen was increased, while kidney/body weight ratio decreased in HSD group. The altered ratio also was observed in the offspring at 15-day-old and 90-day-old. Maternal and fetal plasma antidiuretic hormone was elevated without change in plasma renin activity and Ang I levels, while plasma Ang II was decreased. The key elements of local renal RAS, including angiotensinogen, ACE, ACE2, AT1 and AT2 receptor expression in both mRNA and protein, except renin, were altered following maternal high salt intake. The results suggest that High intake of salt during pregnancy affected fetal renal development associated with an altered expression of the renal key elements of RAS, some alterations of fetal origins remained after birth as possible risks in developing renal or cardiovascular diseases.
{"Chemical": ["nitrogen", "sodium", "urea"]}