Abstract
We recently reported that nitric oxide synthase in the brain can be inhibited not only by nitro-l-arginine (l-NA) but also by its D-enantiomer nitro-d-arginine (d-NA). In the present study, we found that d-NA, when tested in vitro, was 400 times less potent than l-NA. However, when d-NA was injected in vivo, its l-enantiomer, l-NA, was found to rapidly appear in plasma samples (∼1 min), rose to a maximum concentration at 30 min (∼40% conversion), and remained at this plateau for about 5 h. This was consistent with the changes in blood pressure. There was no conversion of l- tod-NA. The results suggested that d-NA has very weak biological actions by itself, but when administered in vivo,d-NA can be converted to l-NA.
Footnotes
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Send reprint requests to: Qiong Wang, M.D., Doctor of Philosophy, Department of Anesthesiology, University of Illinois at Chicago, 1740 W. Taylor Street., Chicago, Illinois.
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1 This work was supported by the National Institutes of Health (HL 52595) and a grant-in-aid from the American Heart Association (National).
- Abbreviations:
- NO
- nitric oxide
- NOS
- NO synthase
- d-NA
- nitro-d-arginine
- l-NA
- nitro-l-arginine
- Received November 26, 1997.
- Accepted August 13, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
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