The effects of nonglycated
bovine serum albumin (BSA) and advanced glycosylation end products of
BSA (AGE-BSA) on vascular responses of control and
metabolic syndrome (MS) rats characterized by
hypertriglyceridemia,
hypertension,
hyperinsulinemia, and
insulin resistance were studied.
Albumin and in vitro prepared
AGE-BSA have vascular effects; however, recent studies indicate that some effects of in vitro prepared AGEs are due to the conditions in which they were generated. We produced AGEs by incubating
glucose with BSA for 60 days under sterile conditions in darkness and at 37 degrees C. To develop MS rats, male Wistar animals were given 30%
sucrose in
drinking water since weanling. Six month old animals were used. Blood pressure,
insulin,
triglycerides, and
serum albumin were increased in MS rats. Contraction of aortic rings elicited with
norepinephrine was stronger. There were no effects of nonglycated BSA or
AGE-BSA on contractions in control or MS rats; however, both groups responded to
L-NAME, an inhibitor of
nitric oxide synthesis. Arterial relaxation induced using
acetylcholine was smaller in MS rats. Nonglycated BSA and
AGE-BSA significantly diminished relaxation in a 35% in the control group but the decrease was similar when using nonglycated BSA and
AGE-BSA. This decrease was not present in the MS rats and was not due to increased RAGEs or altered biochemical characteristics of BSA. In conclusion, both BSA and
AGE-BSA inhibit vascular relaxation in control artic rings. In MS rats the effect is lost possibly due to alterations in endothelial cells that are a consequence of the illness.