Hypertensive response to chronic NO synthase inhibition is different in Sprague-Dawley rats from two suppliers.
Experiments were conducted to determine whether Sprague-Dawley rats from different suppliers have the same hypertensive response to chronic inhibition of nitric oxide synthase. Rats (240-260 g) obtained from either Harlan or Charles River Laboratories were maintained in metabolic cages for baseline (week 0) measurements before receiving Nomega-nitro-L-arginine methyl ester (L-NAME) in the drinking water for 2 wk at 5 or 65 mg . kg-1 . day-1. Baseline values for tail cuff pressure (TCP) were significantly higher in Harlan rats (131 +/- 2 mmHg) compared with Charles River rats (108 +/- 3 mmHg, P < 0.001). At 65 mg . kg-1 . day-1, L-NAME produced a significantly larger increase in TCP in Harlan versus Charles River rats (41 +/- 4 vs. 29 +/- 4%, respectively, P < 0.01). Food and water intake and sodium and water excretion were not different between groups. Urinary excretion of nitrate and nitrite (UNOxV) was significantly reduced in all rats given L-NAME. UNOxV was decreased by 69 +/- 12 and 62 +/- 7% in Harlan and Charles River rats, respectively. The lower dose of L-NAME increased TCP and decreased UNOxV in both Harlan and Charles River rats; these effects were more pronounced in the Harlan rats. These results suggest that NO plays a more significant role in the maintenance of arterial pressure in Sprague-Dawley rats from Harlan compared with Charles River Laboratories. Such findings may also provide insight as to why some of the mechanisms associated with chronic L-NAME treatment are not consistent between laboratories.
Pollock
D M
DM
Vascular Biology Center, Department of Surgery and Department of Physiology and Endocrinology, Medical College of Georgia, Augusta, Georgia 30912-2500, USA.
Rekito
A
A
D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D014644:Genetic Variation; D006973:Hypertension / Q000209:etiology*; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity
D004791:Enzyme Inhibitors; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester