- 作者: Kun-Lun Huang, Chin-Pvng Wu, Bor-Hwang Kang, Yu-Chong Lin
- 作者服務機構: Department of Critical Care Medicine, Tri-Service General Hospital, Institute of Undersea and Hyperbaric Medicine, National Defense Medicine Center, Taipei, Taiwan, ROC, Department of Physiology, University of Hawaii at Manoa, Hawaii, USA
- 中文摘要: --
- 英文摘要: right ventricular hypertrophy, as evidenced by a greaterweight ratio of the right ventricle to the left ventricle andthe interventricular septum compared to the normoxicgroup (46±4 vs. 28±3%). In rats which were previous-1y exposed to chronic hypoxia (half room air for 15 days),acute hypoxia reduced SVR by 14±6% and increasedPVR by 17±4%. Pretreatment with L-NAME furtherinhibited the systemic vasodilatation effect of acute hyp-oxia, but did not enhance pulmonary vasoconstriction.Our results suggest that the release of NO counteractspulmonary vasoconstriction but lowers systemic vasodi-latation on exposure to acute hypoxia, and these re-sponses are attenuated following adaptation to chronichypoxia. Alterations in the nitric oxide (NO) pathway have beenimplicated in the pathogenesis of chronic hypoxia-induced pulmonary hypertension. Chronic hypoxia caneither suppress the NO pathway, causing pulmonaryhypertension, or increase NO release in order to coun-teract elevated pulmonary arterial pressure. We deter-mined the effect of NO synthase inhibitor on hemody-namic responses to acute hypoxia (10% O ) in anesthe-tized rats following chronic exposure to hypobaric hyp-oxia (0.5 atm, air). In rats raised under normoxic condi-tions, acute hypoxia caused profound systemic hypoten-sion and slight pulmonary hypertension without alteringcardiac output. The total systemic vascular resistance(SVR) decreased by 41±5%, whereas the pulmonaryvascular resistance (PVR) increased by 25±6% duringacute hypoxia. Pretreatment with N -nitro-L-argininemethyl ester (L-NAME; 25 mg/kg) attenuated systemicvasodilatation and enhanced pulmonary vasoconstric-tion. In rats with prior exposure to chronic hypobarichypoxia, the baseline values of mean pulmonary andsystemic arterial pressure were significantly higher thanthose in the normoxic grou. Chronic hypoxia caused
- 中文關鍵字: --
- 英文關鍵字: Systemic vasodilation, Pulmonary vasoconstriction, Hemodynamics, Nitric oxide