(Hypertension. 2000;35:451.)
© 2000 American Heart Association, Inc.
Scientific Contributions |
Inhibition of Nitric Oxide Synthesis Potentiates Hypertension During Chronic Glucose Infusion in Rats
From the University of Mississippi Medical Center (M.W.B., S.M.F.) and Jackson State University (C.R.C., J.A.C.), Jackson, Miss.
Correspondence to Michael W. Brands, PhD, Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216. E-mail brands{at}physiology.umsmed.edu
Abstract—Endothelial dysfunction has been proposed to contribute to impaired blood flow control or hypertension in many conditions characterized by hyperinsulinemia or hyperglycemia. However, most studies have focused on whether endothelial dysfunction is present in the established phases of these various hypertensive states, and there is little known concerning the role of the endothelium in the initial stages. This study tested whether nitric oxide production, before endothelial dysfunction develops, plays an important role in counteracting the hypertensive response to chronic glucose infusion. Glucose was infused (18.6 mg/kg per minute IV) for 7 days in 8 normal rats (G) and in 9 rats with a long-term background intravenous infusion of NG-nitro-L-arginine methyl ester (L-NAME) at 10 µg/kg per minute (G+L). Mean arterial pressure (MAP), measured 24 hours per day, increased an average of 
11 mm Hg in the G rats. L-NAME treatment increased MAP an average of 28±2 mm Hg in the G+L rats, and glucose infusion raised MAP >30 mm Hg above that, averaging 155±8 mm Hg by day 6. In addition, heart rate increased from an average of 389±8 bpm to 441±16 bpm by day 6, whereas there was no significant change in the G rats. Glomerular filtration rate decreased significantly with L-NAME treatment and decreased in both groups by day 3 of glucose infusion, reaching lower levels in the G+L rats. These results show that NO is required to minimize the increase in MAP during glucose infusion and suggest that renal and neural mechanisms may be important in mediating that effect.
Key Words: insulin • blood pressure • glomerular filtration rate • endothelium
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