Response of intra-acinar pulmonary microvessels to hypoxia, hypercapnic acidosis, and isocapnic acidosis
Autor: | Koichi Suzuki, Harukuni Tsumura, Kazumi Nishio, Hiroyasu Kudo, Takuya Aoki, Yukio Suzuki, Katsuhiko Naoki, Kei Takeshita, Nagato Sato, Atsushi Miyata, Kazuhiro Yamaguchi |
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Rok vydání: | 1998 |
Předmět: |
Male
medicine.medical_specialty Pulmonary Circulation Physiology Indomethacin Vasodilation 6-Ketoprostaglandin F1 alpha In Vitro Techniques Nitric Oxide Sensitivity and Specificity Microcirculation Hypercapnia Rats Sprague-Dawley Venules Internal medicine medicine Animals Respiratory system Hypoxia Acidosis Microscopy Confocal Chemistry Hemodynamics Hypoxia (medical) Carbon Dioxide Hydrogen-Ion Concentration Epoprostenol Capillaries Rats Arterioles Endocrinology medicine.anatomical_structure NG-Nitroarginine Methyl Ester Biochemistry Prostaglandin-Endoperoxide Synthases Circulatory system medicine.symptom Nitric Oxide Synthase Cardiology and Cardiovascular Medicine Blood vessel |
Zdroj: | Circulation research. 82(6) |
ISSN: | 0009-7330 |
Popis: | Abstract —To elucidate the differential reactivity of pulmonary microvessels in the acini to hypoxia, excessive CO 2 , and increased H + , we investigated changes in the diameter of precapillary arterioles, postcapillary venules, and capillaries in isolated rat lungs on exposure to normocapnic hypoxia (2% O 2 ), normoxic hypercapnia (15% CO 2 ), and isocapnic acidosis (0.01 mol/L HCl). Microvascular diameters were precisely examined using a real-time confocal laser scanning luminescence microscope coupled to a high-sensitivity camera with an image intensifier. Measurements were made under conditions with and without indomethacin or N ω -nitro- l -arginine methyl ester to assess the importance of vasoactive substances produced by cyclooxygenase (COX) or NO synthase (NOS) as it relates to the reactivity of pulmonary microvessels to physiological stimuli. We found that acute hypoxia contracted precapillary arterioles that had diameters of 20 to 30 μm but did not constrict postcapillary venules of similar size. COX- and NOS-related vasoactive substances did not modulate hypoxia-elicited arteriolar constriction. Hypercapnia induced a distinct venular dilatation closely associated with vasodilators produced by COX but not by NOS. Arterioles were appreciably constricted in isocapnic acidosis when NOS, but not COX, was suppressed, whereas venules showed no constrictive response even when both enzymes were inhibited. Capillaries were neither constricted nor dilated under any experimental conditions. These findings suggest that reactivity to hypoxia, CO 2 , and H + is not qualitatively similar among intra-acinar microvessels, in which COX- and NOS-associated vasoactive substances function differently. |
Databáze: | OpenAIRE |
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