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- Sjöberg, Trygve, et al.
(författare)
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Contractile properties of lymphatics from the human lower leg
- 1991
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Ingår i: Lymphology. - 0024-7766. ; 24:1, s. 16-21
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Tidskriftsartikel (refereegranskat)abstract
- Lower leg lymphatics, taken from seven volunteers, were investigated in vitro. Isometric contractions were induced by noradrenaline, 5-hydroxytryptamine (5-HT), prostaglandin F2 alpha (PGF2 alpha), and the thromboxane A2 (TXA2)-mimetic U-44069. Noradrenaline induced phasic contractions in 6 of 7 segments. The amplitude of the contractions were up to 100% of a previous K+ (124mM)-induced contraction and the frequency at 10(-6)M of noradrenaline was 5-13 min-1. These contractions were unaffected by propranolol (10(-6)M), but they were abolished by phentolamine (10(-6)M). Noradrenaline had an Emax (tonic contraction) of 7% of the K+ (124mM) contraction (n = 7) and the pEC50-value was 6.9 (n = 3). The corresponding values for 5-HT were 21% (n = 5) and 6.4 (n = 3). PGF2 alpha elicited contractions in all segments investigated (Emax = 87%, pEC50 = 5.8, n = 5). U-44069 had high contractile capacity and potency in all investigated segments (Emax = 137%, pEC50 = 8.9, n = 7). Phasic contractions were elicited also by 5-HT, PGF2 alpha and U-44069. Compared to earlier studies of human peripheral lymphatics, these results show that there are regional differences in susceptibility to these vasoactive agents.
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| 2. |
- Sjöberg, Trygve, et al.
(författare)
-
In vitro effects of a thromboxane A2-analogue U-46619 and noradrenaline on contractions of the human thoracic duct
- 1991
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Ingår i: Lymphology. - 0024-7766. ; 24:3, s. 113-115
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Tidskriftsartikel (refereegranskat)abstract
- A piece of a human thoracic duct removed at operation was investigated in organ baths. The duct was cut in 8 ring segments each about 1mm long and isometric tension recorded. The segments were exposed to a potassium rich (124mM) Krebs buffer solution. In only two of the segments were contractions induced (7.2 and 1.0mN, respectively). Noradrenaline and the thromboxane mimetic U-46619 induced tonic and phasic contractions. At a noradrenaline concentration of 10(-5)M the phasic contractions had a frequency of 5 min-1. The highest frequency, 9 min-1, was recorded with 3 x 10(-10)M of U-46619 present in the bath. Noradrenaline had a mean Emax of 50% of the previous K+ (124mM)-induced contraction, and the mean pEC50-value was 6.7. The Emax and pEC50-values of U-46619 were 142% and 9.5, respectively. Postjunctional alpha-adrenoceptors and thromboxane A2-receptors may play a role in the contractility of the human thoracic duct.
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