Regulation ofPulmonary Endothelial CellShape byTRP- Mediated CalciumEntry*

dent on thelevel ofshear andtheduration. Todetermine therelative roles ofhemodynamics and chronic hypoxia inregulating eNOS andpreproET-1 expression inthepulmonary circulation, we studied adult maleratsafter leftpulmonary arteiy (LPA) banding followed by4weeksofnormoxia or 1weekofnormoxia and3weeks ofhypoxia (FIo2=0.12). Methods Hemodynamic measurements were madeon catheterized animals. Western blotanalysis ofeNOSprotein was performed on crudelung homogenates. We also carried outNorthern blotanalysis forpreproET-1 messenger RNA(mRNA) on total RNA extracted fromthelungs of therats. Results Innormoxic rats, LPAstenosis reduced blood flow tothe left lung from9.8±0.9 (sham surgeiy controls) to0.8±0.4 mL/100mg/min (p<0.05); there was nota significant in¬ creaseinright lung blood flow. eNOSprotein content inthe left lung ofnormoxic ratswith LPAstenosis wasdecreased by 32±7%(p<0.05) incomparison with the content intheright lung, andright lung eNOS content was unchanged in comparison withthecontent inshamcontrols. PreproET-1 mRNA content decreased by9.6-fold intheleft lung ofLPA stenosis ratsincomparison with shamcontrols (p<0.05), and there was nochange inpreproET-1 mRNA intheright lung. After 3weeks ofhypoxia, LPAstenosis reduced blood flow to theleftlung from5.8±0.6 to1.5±0.4 mL/100mg/min (p<0.05) andincreased blood flow totheright lung from 5.8±0.5 to10.0±1.4 mL/100mg/min (p<0.05). Despite reduced blood flowandpressure totheleftlung and increased flow andpressure totheright lung, left andright lung eNOSprotein contents were notdifferent fromeNOS