Role of nitric oxide towards vasodilator effects of substance P and ATP in human forearm vessels

Masanari Shiramoto, Tsutomu Imaizumi, Yoshitaka Hirooka, Toyonari Endo, Takashi Namba, Jun Ichi Oyama, Kiyoshi Hironaga, Akira Takeshita

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Abstract

1. It has been shown in animals that substance P as well as acetylcholine releases endothelium-derived nitric oxide and evokes vasodilatation and that ATP-induced vasodilatation is partially mediated by nitric oxide. The aim of this study was to examine whether vasodilator effects of substance P and ATP are mediated by nitric oxide in humans. 2. In healthy volunteers (n = 35), we measured forearm blood flow by a strain-gauge plethysmograph while infusing graded doses of acetylcholine, substance P, ATP or sodium nitroprusside into the brachial artery before and after infusion of N(G)-monomethyl-L-arginine (4 or 8 μmol/min for 5 min). In addition, we measured forearm blood flow while infusing substance P before and during infusion of L-arginine (10 mg/min, simultaneously), or before and 1 h after oral administration of indomethacin (75 mg). 3. Acetylcholine, substance P, ATP or sodium nitroprusside increased forearm blood flow in a dose-dependent manner, N(G)-Monomethyl-L-arginine decreased basal forearm blood flow and inhibited acetylcholine-induced vasodilatation but did not affect substance P-, ATP-, or sodium nitroprusside-induced vasodilatation. Neither supplementation of L-arginine nor pretreatment with indomethacin affected substance P-induced vasodilatation. 4. Our results suggest that, in the human forearm vessels, substance P-induced vasodilatation may not be mediated by either nitric oxide or prostaglandins and that ATP-induced vasodilatation may also not be mediated by nitric oxide.

Original languageEnglish
Pages (from-to)123-131
Number of pages9
JournalClinical Science
Volume92
Issue number2
DOIs
Publication statusPublished - Jan 1 1997

All Science Journal Classification (ASJC) codes

  • Medicine(all)

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    Shiramoto, M., Imaizumi, T., Hirooka, Y., Endo, T., Namba, T., Oyama, J. I., Hironaga, K., & Takeshita, A. (1997). Role of nitric oxide towards vasodilator effects of substance P and ATP in human forearm vessels. Clinical Science, 92(2), 123-131. https://doi.org/10.1042/cs0920123