Angiotensin converting enzyme activity and nitric oxide level in serum patients with dehydration.

Angiotensin converting enzyme (ACE) and nitric oxide (NO) have been suggested to be involved in the regulation of fluid homeostasis. In the present investigation, ACE activity and NO levels were determined in serum of 20 patients (10 men and 10 women) with dehydration caused by gastroenterocolitis and 20 healthy individuals (10 men and 10 women). Serum and tissue ACE activity was determined by spectrophotometric method using hippuryl-l-histidyl-l-leucine (Hip-His-Leu) as a substrate. NO synthesis was determined by measuring the products of NO, nitrite and nitrate. The concentration of nitrites was determined by classic colorimetric method using Griess reagent. Nitrate concentration was determined indirectly by their reduction with elementary zinc into nitrite. Results have shown that serum ACE activity in patients with dehydration (36,46+/-2,74 U/L) is statistically higher then in healthy individuals (28,71+/-1,77 U/L, p<0,05). The average level of nitrites/nitrates in serum of patients with dehydration (30,57+/-1,05 microM; mean +/- SEM) is also statistically higher then in healthy individuals (12,44+/-0,60 microM, p<0,0001). There was no correlation between ACE activity and NO production. The results indicate that ACE and NO may participate in the regulation of the alteration in blood flow and in the regulation of the water balance in patients with dehydration.