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- Ekelund, Ulf, et al.
(författare)
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In-vivo effects of endothelin-1 and ETA receptor blockade on arterial, venous and capillary functions in skeletal muscle
- 1993
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 148:3, s. 273-283
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Tidskriftsartikel (refereegranskat)abstract
- Results from in vitro studies have indicated that endothelin-1 is a main candidate for endothelium-derived contracting factors. The aim of this in vivo study was to describe in quantitative terms the effects of endothelin-1 (ET-1), and of ETA receptor blockade, on vascular tone (resistance) in large-bore arterial resistance vessels (> 25 microns), small arterioles (< 25 microns) and the veins, as well as on capillary pressure and fluid exchange in cat gastrocnemius muscle. Endothelin-1 (100-1600 ng kg-1 min-1, i.a.) elicited, after an initial transient dilation, a strong dose-dependent constrictor response in all three consecutive vascular sections, yet with a preferential action on the small arterioles and the veins. The vasoconstriction developed very slowly over about 1 h and was also long-lasting after cessation of the infusion. Our main quantitative analysis refers to effects elicited by 20 min long i.a. infusions of ET-1 at a dose of 400 ng kg-1 min-1. At the end of this period, the peptide caused, on average, a three-fold increase in total regional vascular resistance, in turn explained by a 70% increase in large-bore arterial resistance, a 280% increase in arteriolar resistance and a 220% increase in venous resistance. The latter effect was also manifested as a pronounced capacitance response, and as a decrease in the pre- to post-capillary resistance ratio leading regularly to a rise in capillary pressure, net transcapillary fluid filtration and oedema formation which is unusual for a vasoconstrictor. The new specific competitive ETA receptor antagonist FR 139317 was found to be fully effective in vivo, insofar as it abolished the constrictor response to endothelin-1. ETA receptor blockade, or administration of phosphoramidon, an inhibitor of ET-1 production, did not influence the level of basal vascular tone, indicating no significant endogenous release of ET-1 under resting conditions. This contrasts to the established pronounced endogenous release of endothelium-derived nitric oxide. Finally, vascular myogenic regulation was found not to be mediated by ET-1. The results, taken together, suggest a possible role of ET-1 in long-term, rather than short-term, regulation of vascular tone in vivo, perhaps especially during pathophysiological conditions.
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| 2. |
- Ekelund, Ulf, et al.
(författare)
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Myogenic vascular regulation in skeletal muscle in vivo is not dependent of endothelium-derived nitric oxide
- 1992
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 144:2, s. 199-207
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Tidskriftsartikel (refereegranskat)abstract
- The hypothesis, based on in vitro experiments on large conduit arteries, that endothelium-derived nitric oxide is a mediator of vascular myogenic reactivity was tested in cat gastrocnemius muscle in vivo. This was done by comparing, in the absence and presence of effective endothelium-derived nitric oxide blockade by the specific inhibitors NG-monomethyl-L-arginine or NG-nitro-L-arginine methyl ester, myogenic responses in defined consecutive vascular sections to dynamic vascular transmural pressure stimuli, to arterial occlusion (reactive hyperaemia), and to arterial pressure changes (autoregulation of blood flow and capillary pressure). The results demonstrated that the myogenic vascular reactivity to quick ramp transmural pressure stimuli was not attenuated by endothelium-derived nitric oxide blockade, but rather reinforced. The amplitude of the reactive hyperaemia response was unaffected by endothelium-derived nitric oxide blockade, but its duration was shortened because of faster myogenic constriction, especially of large-bore arterial resistance vessels greater than 25 microns, in the recovery phase. Both the improved myogenic responsiveness to transmural pressure stimuli and the shortening of the reactive hyperaemia by endothelium-derived nitric oxide blockade suggested that endothelium-derived nitric oxide released in vivo acts as a 'metabolic' factor which certainly does not improve, but rather depresses myogenic vascular reactivity. Autoregulation of blood flow and capillary pressure were well preserved in the presence of endothelium-derived nitric oxide blockade. It was concluded from the results of these multifaceted tests that myogenic vascular regulation in skeletal muscle in vivo seems independent of endothelium-derived nitric oxide.(ABSTRACT TRUNCATED AT 250 WORDS)
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| 3. |
- Riklund, Katrine, et al.
(författare)
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Radioimmunoscintigraphy of gynecologic tumors with 131I-labeled anti-PLAP monoclonal antibodies.
- 1991
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Ingår i: Acta Radiologica. - 0284-1851 .- 1600-0455. ; 32:5, s. 375-380
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Tidskriftsartikel (refereegranskat)abstract
- Radioimmunoscintigraphy (RIS) was performed in 20 patients with gynecologic tumors, 14 ovarian, 5 cervical, and one endometrial carcinoma. One murine monoclonal antibody (mab) against placental alkaline phosphatase (H7) was used after radiolabeling with 131I. The labeling procedure yielded antibodies with specific activity varying between 60 and 73 MBq/mg mab. Each patient received 57 to 100 MBq of the preparation. RIS was performed 7 to 35 days later. Patients with ovarian adenocarcinoma had an accumulation of activity on RIS at tumor sites (79%, 11/14) verified by ultrasonography, CT, and clinical examination. A low or absent accumulation of activity was seen in patients with cervical tumors. The patient with an endometrial adenocarcinoma was seen to have an activity accumulation at RIS corresponding to tumor sites determined by ultrasound and/or CT. It is concluded that RIS using monoclonal antibodies against placental alkaline phosphatase can provide information which will supplement that gained from other investigations of patients with ovarian adenocarcinomas.
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