| 1. |
- Dahm, Peter L., et al.
(författare)
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Binding of [3H]-5-hydroxytryptamine to human coronary artery and bypass graft vessels
- 1996
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Ingår i: Cardiovascular Research. - 1755-3245. ; 31:5, s. 800-806
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: 5-Hydroxytryptamine (5-HT) has a wide range of vascular effects mediated via specific receptors and it has been suggested to be a mediator in ischemic heart disease. The aim of the present study was to localise the 5-HT receptors within the vessel wall. METHODS: Epicardial coronary arteries obtained from patients undergoing cardiac transplantation, internal mammary arteries from heart donors and saphenous veins from patients undergoing coronary bypass surgery, were sectioned and incubated with [3H]-5-HT for in vitro receptor autoradiography. RESULTS: Microscopic analysis of high resolution autoradiographic images revealed a similar pattern of [3H]-5-HT binding in epicardial coronary and internal mammary artery, where it predominated in the lamina muscularis. In the saphenous vein, binding increased towards the adventitia which showed dense, displaceable binding to the vasa vasorum as well as to nerve-like structures, from which binding was only partially displaced. Computer-assisted densitometric analysis of low resolution autoradiographs revealed a high degree of specific binding to all vessels examined. CONCLUSIONS: The distribution of the [3H]-5-HT binding is different in the saphenous vein compared to epicardial coronary and internal mammary artery. The dense binding to vasa vasorum in the saphenous vein suggests a role for 5-HT in closure of these nutrient vessels, which could contribute to the formation of atherosclerotic changes in saphenous vein grafts.
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| 2. |
- Dahm, Peter
(författare)
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Nitric oxide in experimental sepsis
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nitric oxide (NO) is important in the control of blood pressure and organ perfusion. In septic shock, NO produced by inducible NO-synthase (NOS) has been claimed to mediate pathological vasodilation and cell injury, while NO produced by constitutive NOS may be protective in counteracting hypoperfusion and organ injury. This thesis comprises studies on the effects of inhaled NO on pulmonary function in a porcine model of unresuscitated Gram-negative septic shock and acute lung injury (ALI). In this model and in normal pigs, we also investigated the effects of non-selective NOS inhibition on global and regional haemodynamics and oxygen extraction. NO inhalation: Inhaled NO (57 and 60 ppm) selectively attenuated pulmonary vasoconstriction without direct effects on the systemic circulation. Early NO inhalation preserved gas exchange by reducing venous admixture and alveolar dead space, but had no effects on respiratory mechanics. The effects on pulmonary haemodynamics and gas exchange were repeatable. Inhaled NO may mitigate endotoxic lung injury by reducing leukocyte sequestration in the pulmonary microvasculature. NOS inhibition: In both normal and endotoxic pigs, the pulmonary vasculature was more sensitive to the vasoconstricting effects of NOS inhibition than the systemic. In normal pigs, this pulmonary vasoconstriction was enhanced by prior stimulation with acetylcholine. The enhancement may be related to an associated release of a vasoconstricting prostanoid. In endotoxic shock, NOS inhibition caused several animals, with extreme pulmonary hypertension, to die before the end of the observation time. In spite of the fatal overall effects, hepatic perfusion was unharmed by NOS inhibition. The capacity to increase oxygen extraction, in response to the decrease in oxygen delivery, was preserved. In hypodynamic shock, compensatory mechanisms other than NO may be more important in the regulation of hepatic blood flow.
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| 3. |
- Dahm, S L, et al.
(författare)
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Charcoal as an airway isoflurane reflection filter
- 1998
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Ingår i: European Journal of Anaesthesiology. - : Ovid Technologies (Wolters Kluwer Health). - 1365-2346 .- 0265-0215. ; 15:2, s. 230-233
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Tidskriftsartikel (refereegranskat)abstract
- The isoflurane-saving and CO2-retaining effects of a charcoal filter were compared with a Siemens standard heat and moisture (HME) exchanger and an emptied specimen (dummy). Isoflurane was delivered during the inspiratory phase and consumption investigated at 10, 15 and 25 cycles min-1. The investigation was performed by ventilation with humidified air with a constant end-tidal CO2 and temperature. For a comparison, isoflurane was delivered in a conventional manner via the ventilator. The arrangement with a charcoal filter reduced the isoflurane consumption by a factor of 2.0-2.6, depending on ventilatory rate. Most of the saving was a result of the method of isoflurane delivery (factor 1.4-2.0), while adding the reflector gave a further reduction (factor 1.3-1.5). One circumstance that reduced the net efficiency of the charcoal filter was that it also reflected CO2; consequently, total minute ventilation had to be increased to maintain constant end-tidal CO2.
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