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This Article Full Text Full Text (PDF) All Versions of this Article: 292/6/L1515    most recent 00252.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Aschner, J. L. Articles by Fike, C. D. Search for Related Content PubMed PubMed Citation Articles by Aschner, J. L. Articles by Fike, C. D.

Heat shock protein 90 modulates endothelial nitric oxide synthase activity and vascular reactivity in the newborn piglet pulmonary circulation

¹Department of Pediatrics and ²The Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee; and ³Department of Pediatrics, Wake Forest University School of Medicine, Winston-Salem, North Carolina

Submitted 5 July 2006 ; accepted in final form 26 February 2007

Heat shock protein 90 (Hsp90) binding to endothelial nitric oxide synthase (eNOS) is an important step in eNOS activation. The conformational state of bound Hsp90 determines whether eNOS produces nitric oxide (NO) or superoxide (O₂^–). We determined the effects of the Hsp90 antagonists geldanamycin (GA) and radicicol (RA) on basal and ACh-stimulated changes in vessel diameter, cGMP production, and Hsp90:eNOS coimmunoprecipitation in piglet resistance level pulmonary arteries (PRA). In perfused piglet lungs, we evaluated the effects of GA and RA on ACh-stimulated changes in pulmonary arterial pressure (Ppa) and perfusate accumulation of stable NO metabolites (NOx^–). The effects of GA and RA on ACh-stimulated O₂^– generation was investigated in cultured pulmonary microvascular endothelial cells (PMVEC) by dihydroethidine (DHE) oxidation and confocal microscopy. Hsp90 inhibition with GA or RA reduced ACh-mediated dilation, abolished the ACh-stimulated increase in cGMP, and reduced eNOS:Hsp90 coprecipitation. GA and RA also inhibited the ACh-mediated changes in Ppa and NOx^– accumulation rates in perfused lungs. ACh increased the rate of DHE oxidation in PMVEC pretreated with GA and RA but not in untreated cells. The cell-permeable superoxide dismutase mimetic M40401 reversed GA-mediated inhibition of ACh-induced dilation in PRA. We conclude that Hsp90 is a modulator of eNOS activity and vascular reactivity in the newborn piglet pulmonary circulation. Uncoupling of eNOS with GA or RA inhibits ACh-mediated dilation by a mechanism that involves O₂^– generation.

pulmonary resistance arteries; isolated perfused lungs; superoxide; geldanamycin; radicicol