Glucose concentration was assayed using an enzymatic SERA-PAK® Plus from Bayer Corporation (Sées, France). Serum insulin was determined using a commercial radioimmunoassay (RIA) specific for rats (Linco Research Inc., Missouri, USA); its sensitivity was 0.1 ng/mL, and intra- and interassay coefficients of variation were 5 and 10%, respectively. The HOMA-IR was calculated from the fasting glucose and insulin concentrations as previously reported [9 (link)].
Triglycerides were determined by commercially available procedures (Randox Laboratories Ltd., Antrim, United Kingdom). Endothelin 1 was quantified in serum by high-pressure liquid chromatography (UPLC), as previously reported [20 (link)]. Systolic arterial blood pressure was measured in conscious adult animals using the tail-cuff method; the cuff was connected to a pneumatic pulse transducer (Narco Bio-Systems Inc., Healthdyne Co.) and a programmed electrosphygmomanometer. The mean of five independent determinations was calculated.
Triglycerides were determined by commercially available procedures (Randox Laboratories Ltd., Antrim, United Kingdom). Endothelin 1 was quantified in serum by high-pressure liquid chromatography (UPLC), as previously reported [20 (link)]. Systolic arterial blood pressure was measured in conscious adult animals using the tail-cuff method; the cuff was connected to a pneumatic pulse transducer (Narco Bio-Systems Inc., Healthdyne Co.) and a programmed electrosphygmomanometer. The mean of five independent determinations was calculated.