title: Membrane physiological reactions of human arteriosclerotic coronary arteries to hypoxia.
abstract: Human coronary arteries were taken from heart transplant patients. Arteriosclerotic arteries were more depolarized and constricted over the whole PO2 range between 535 and 0 mm Hg. During oxygen deficiency, control preparations showed a maximal hyperpolarization of delta V = 10.9 mV and a maximal relaxation of delta T = 0.466 g. Arteriosclerotic arteries, however, became hyperpolarized by merely delta V = 7.1 mV and relaxed by delta T = 0.258 g. In normal coronary arteries, indomethacin reduced the hypoxic hyperpolarization and dilation at 30 mm Hg PO2 by about 51%. The reduction was 26% in arteriosclerotic vessels. The complete removal of the endothelium caused a 49% (74%) restriction of dilatory vascular reactivity. The relationship was quite similar for a carbogen Krebs solution. The hyperpolarizing and dilatory contribution by prostacyclin was 32% in normal and 12% in arteriosclerotic coronary arteries. The remainder could be attributed to the basal release of the endothelial dilator endothelium-derived hyperpolarizing factor (EDHF). Thus, it may be concluded that in arteriosclerotic blood vessels, prostacyclin (PGI2) synthesis and release are predominantly diminished. Finally, we found that the ratio PGI2/EDHF in the voltage and tension changes strongly shifted to the PGI2 side with a declining oxygen concentration. This is true for normal and arteriosclerotic vessels. In accordance with the activation curve for vascular smooth muscle, the hyperpolarization leads to relaxation via a closure of Ca2+ channels. Hyperpolarization of 2.5 mV reduces the tension developed by one-half.
mesh_terms: D015220:Calcium Channels / Q000502:physiology; D003324:Coronary Artery Disease / Q000503:physiopathology*; D003331:Coronary Vessels / Q000503:physiopathology*; D011464:Epoprostenol / Q000378:metabolism; D006801:Humans; D000860:Hypoxia; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008564:Membrane Potentials; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology*; D010100:Oxygen / Q000502:physiology*
chemical_list: D015220:Calcium Channels; D011464:Epoprostenol; D010100:Oxygen; D007213:Indomethacin