Ling Wang1,2, Courtney E Sparacino-Watkins1,2, Jun Wang3, Nadeem Wajih4, Paul Varano1, Qinzi Xu1, Eric Cecco1, Jesús Tejero1,2, Manoocher Soleimani5, Daniel B Kim-Shapiro4,6, Mark T Gladwin1,2. 1. Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania. 2. Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania. 3. Hubei University of Technology, Wuhan, P. R. China. 4. Department of Physics, Wake Forest University, Winston-Salem, North Carolina. 5. Department of Medicine, University of Cincinnati, Cincinnati, Ohio. 6. Translational Science Center, Wake Forest University, Winston-Salem, North Carolina.
Abstract
BACKGROUND AND PURPOSE: Although it has been reported that bovine carbonic anhydrase CAII is capable of generating NO from nitrite, the function and mechanism of CAII in nitrite-dependent NO formation and vascular responses remain controversial. We tested the hypothesis that CAII catalyses NO formation from nitrite and contributes to nitrite-dependent inhibition of platelet activation and vasodilation. EXPERIMENT APPROACH: The role of CAII in enzymatic NO generation was investigated by measuring NO formation from the reaction of isolated human and bovine CAII with nitrite using NO photolysis-chemiluminescence. A CAII-deficient mouse model was used to determine the role of CAII in red blood cell mediated nitrite reduction and vasodilation. KEY RESULTS: We found that the commercially available purified bovine CAII exhibited limited and non-enzymatic NO-generating reactivity in the presence of nitrite with or without addition of the CA inhibitor dorzolamide; the NO formation was eliminated with purification of the enzyme. There was no significant detectable NO production from the reaction of nitrite with recombinant human CAII. Using a CAII-deficient mouse model, there were no measurable changes in nitrite-dependent vasodilation in isolated aorta rings and in vivo in CAII-/- , CAII+/- , and wild-type mice. Moreover, deletion of the CAII gene in mice did not block nitrite reduction by red blood cells and the nitrite-NO-dependent inhibition of platelet activation. CONCLUSION AND IMPLICATIONS: These studies suggest that human, bovine and mouse CAII are not responsible for nitrite-dependent NO formation in red blood cells, aorta, or the systemic circulation.
BACKGROUND AND PURPOSE: Although it has been reported that bovine carbonic anhydrase CAII is capable of generating NO from nitrite, the function and mechanism of CAII in nitrite-dependent NO formation and vascular responses remain controversial. We tested the hypothesis that CAII catalyses NO formation from nitrite and contributes to nitrite-dependent inhibition of platelet activation and vasodilation. EXPERIMENT APPROACH: The role of CAII in enzymatic NO generation was investigated by measuring NO formation from the reaction of isolated human and bovineCAII with nitrite using NO photolysis-chemiluminescence. A CAII-deficient mouse model was used to determine the role of CAII in red blood cell mediated nitrite reduction and vasodilation. KEY RESULTS: We found that the commercially available purified bovineCAII exhibited limited and non-enzymatic NO-generating reactivity in the presence of nitrite with or without addition of the CA inhibitor dorzolamide; the NO formation was eliminated with purification of the enzyme. There was no significant detectable NO production from the reaction of nitrite with recombinant humanCAII. Using a CAII-deficient mouse model, there were no measurable changes in nitrite-dependent vasodilation in isolated aorta rings and in vivo in CAII-/- , CAII+/- , and wild-type mice. Moreover, deletion of the CAII gene in mice did not block nitrite reduction by red blood cells and the nitrite-NO-dependent inhibition of platelet activation. CONCLUSION AND IMPLICATIONS: These studies suggest that human, bovine and mouseCAII are not responsible for nitrite-dependent NO formation in red blood cells, aorta, or the systemic circulation.
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Authors: Ling Wang; Courtney E Sparacino-Watkins; Jun Wang; Nadeem Wajih; Paul Varano; Qinzi Xu; Eric Cecco; Jesús Tejero; Manoocher Soleimani; Daniel B Kim-Shapiro; Mark T Gladwin Journal: Br J Pharmacol Date: 2019-12-23 Impact factor: 8.739