title: Mechanical and biochemical events during hypoxia-induced relaxations of rabbit aorta.
abstract: Hypoxic relaxation of norepinephrine contractions of isolated rabbit aorta is rapid, whereas relaxation of KCl contractions is slower and blunted. The data given here suggest that with receptor-evoked contractions of rabbit aorta, the energy-limitation of ATP-dependent K+ channels and other sarcolemmal channels, myosin light chain kinase, and actin-activated myosin ATPase are probably not involved in oxidative energy-contraction coupling. The data strongly support the hypothesis that the rate limiting, energy-dependent step is upstream to myosin light chain kinase, which is 50% inhibited at an ATP concentration of about 0.5 mM. This energy-dependent step may be in the inositol phospholipid transduction system, as we have previously postulated (Coburn et al., 1988). In contrast the energy-limited reaction during KCl contractions appears to be the actin-activated myosin ATPase which is 50% inhibited at a mean ATP concentration of about 0.1 mM.
authors.affiliation: Department of Pharmacology, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, NJ 08543.
authors.forename: S
authors.initials: S
authors.lastname: Moreland
authors.forename: R F
authors.initials: RF
authors.lastname: Coburn
authors.forename: C B
authors.initials: CB
authors.lastname: Baron
authors.forename: R S
authors.initials: RS
authors.lastname: Moreland
mesh_terms: D000199:Actins / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000502:physiology; D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism / Q000502:physiology; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004734:Energy Metabolism / Q000502:physiology; D004789:Enzyme Activation / Q000502:physiology; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology*; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism; D008297:Male; D009126:Muscle Relaxation / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000503:physiopathology*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D009218:Myosins / Q000378:metabolism; D010084:Oxidation-Reduction; D010725:Phosphocreatine / Q000378:metabolism; D011817:Rabbits
chemical_list: D000199:Actins; D007295:Inositol Phosphates; D010725:Phosphocreatine; D000255:Adenosine Triphosphate; D009219:Myosin-Light-Chain Kinase; D000251:Adenosine Triphosphatases; D009218:Myosins