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  • 1
    Electronic Resource
    Electronic Resource
    Age-related decrease in the ef fect of parathyroid hormone-related protein on cytosolic free calcium level and tension in rat aortic smooth muscle (1995)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1995), S. 517-522 
    Details
    ISSN: 1432-1912
    Keywords: Key words Parathyroid hormone-related protein ; Cyclic AMP ; Rat aortic smooth muscle ; Aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Age-related changes in the effect of parathyroid hormone-related protein (PTHrP) on the cytosolic free calcium level ([Ca2+]i) and on the tension in rat aortic smooth muscle were investigated. The possible involvement of cAMP, a second messenger of PTHrP, in such changes was also investigated. Spiral aortic strip preparations without endothelium from 8-weeks, 6-months, and 24-months old rats were treated with fura 2/AM, and the fluorescence ratio R340/380, an index of [Ca2+]i was measured. Simultaneously, the tension of the preparations was measured. PTHrP-(1–34) and dibutyryl cAMP produced concentration-dependent decreases in the tension and in R340/380 in aortas precontracted with phenylephrine (10-7 M). These effects were significantly lower in the aortas of 24-months old rats than in the vessels of 8-weeks and 6-months old rats. The effects were similar in the aortas of 8-weeks and 6-months old rats. PTHrP-(1–34) concentration-dependently increased cAMP production in vascular smooth muscle cells (VSMCs) from 8-weeks old rats. However, the increase in cAMP production was significantly lower in cultured VSMCs from 6-months and 24-months old rats than in cells from 8-weeks old rats. These results suggest that the reduced cAMP production stimulated by PTHrP and the reduced effects of cAMP with aging might contribute to the age-related changes in the decreases in tension and [Ca2+]i in response to PTHrP in the rat aorta.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00171043
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  • 2
    Electronic Resource
    Electronic Resource
    Age-related decrease in the effect of parathyroid hormone-related protein on cytosolic free calcium level and tension in rat aortic smooth muscle (1995)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1995), S. 517-522 
    Details
    ISSN: 1432-1912
    Keywords: Parathyroid hormone-related protein ; Cyclic AMP ; Rat aortic smooth muscle ; Aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Age-related changes in the effect of parathyroid hormone-related protein (PTHrP) on the cytosolic free calcium level ([Ca+]i) and on the tension in rat aortic smooth muscle were investigated. The possible involvement of cAMP, a second messenger of PTHrP, in such changes was also investigated. Spiral aortic strip preparations without endothelium from 8-weeks, 6-months, and 24-months old rats were treated with fura 2/AM, and the fluorescence ratio R340/380, an index of [Ca+]i was measured. Simultaneously, the tension of the preparations was measured. PTHrP-(1–34) and dibutyryl cAMP produced concentration-dependent decreases in the tension and in R340/380 in aortas precontracted with phenylephrine (10−7 M). These effects were significantly lower in the aortas of 24-months old rats than in the vessels of 8-weeks and 6-months old rats. The effects were similar in the aortas of 8-weeks and 6-months old rats. PTHrP-(1–34) concentration-dependently increased cAMP production in vascular smooth muscle cells (VSMCs) from 8-weeks old rats. However, the increase in cAMP production was significantly lower in cultured VSMCs from 6-months and 24-months old rats than in cells from 8-weeks old rats. These results suggest that the reduced cAMP production stimulated by PTHrP and the reduced effects of cAMP with aging might contribute to the age-related changes in the decreases in tension and [Ca+]i in response to PTHrP in the rat aorta.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00171043
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Vascular relaxing mechanism of denopamine in isolated canine coronary, femoral, mesenteric, and renal arteries (1993)
    Springer
    Heart and vessels 8 (1993), S. 176-180 
    Details
    ISSN: 1615-2573
    Keywords: Denopamine ; Vascular smooth muscle relaxation ; Isolated canine arteries ; α-Adrenoceptor blocking action ; β1-Adrenergic action
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We investigated the mechanism of vascular relaxation produced by denopamine (deno), an oral positive inotropic agent that has selective β1-adrenergic action. Deno concentration-dependently (0.1 µM–30 µM) relaxed ring segments of canine femoral, mesenteric, and renal arteries which were partially precontracted with 1 µm phenylephrine or norepinephrine, but did not relax those precontracted with 5 µM prostaglandin F2α or 40 mM K+. The relaxation was not significantly inhibited by pretreatment with 10 µM propranolol or metoprolol. Deno produced a parallel rightward shift in concentration-response curves to phenylephrine in femoral and renal arteries. The Schild plot yielded linear regressions of slopes of 1.301 ± 0.106 and 0.823 ± 0.122, respectively, which were not significantly different from unity. The pA2 values of Deno against phenylephrine in femoral and renal arteries were 5.41 ± 0.03 and 5.76 ± 0.06, respectively. On the other hand, Deno concentration-dependently (10 nM–10 µM) relaxed ring segments of canine coronary arteries which were partially precontracted with 5 µM prostaglandin F2α. The relaxation was significantly inhibited by pretreatment with 10 µM metoprolol. In conclusion, vascular smooth muscle relaxation by Deno was mediated through β1-adrenergic action in canine coronary arteries and through the blocking effect of α-adrenoceptors in canine femoral, mesenteric, and renal arteries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01744739
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  • 4
    Electronic Resource
    Electronic Resource
    Acetylcholine-induced endothelium-dependent vascular smooth muscle relaxation in nitroglycerin-tolerant isolated rat aorta (1991)
    Springer
    Heart and vessels 6 (1991), S. 175-180 
    Details
    ISSN: 1615-2573
    Keywords: Nitroglycerin ; Nitroglycerin tolerance ; Acetylcholine ; Endothelium-derived relaxing factor (EDRF) ; Cyclic GMP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Nitroglycerin (NTG) tolerance is recognized clinically, and its pharmacological mechanism has been thought to be due to a decrease in the accumulation of cyclic GMP (cGMP) which is a second messenger of NTG. Endothelium-derived relaxing factor (EDRF) also relaxes vascular smooth muscle through the activation of soluble guanylate cyclase and the production of cGMP. The purpose of this study was to investigate acetylcholine (ACh)-induced endothelium-dependent relaxation and cGMP response in NTG-tolerant isolated rat aorta. Ring strips prepared from the thoracic aorta of male Wistar rats were mounted in tissue baths and contracted with 10−6 M norepinephrine. NTG and ACh relaxation responses were compared before and after 1 h treatment with 5×10−4 M NTG. The chronological changes in tissue cGMP levels by 10−6 M NTG and ACh were compared between a control group (untreated) and NTG-tolerant group (treated with 5×10−4 M NTG for 1 h). The NTG dose-response curve shifted markedly to the right, but the ACh dose-response curve shifted to the left after the induction of NTG tolerance. In the control group, both NTG and ACh elevated the tissue cGMP levels, but in the NTG-tolerant group only ACh elevated cGMP significantly. However, in the NTG-tolerant group, the cGMP increase induced by ACh was smaller than that in the control group. These results suggest that NTG tolerance does not decrease, but rather augments ACh-induced endothelium-dependent vascular smooth muscle relaxation in isolated rat aorta.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02058283
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  • 5
    Electronic Resource
    Electronic Resource
    The contractile mechanism of beraprost sodium, a stable prostacyclin analog, in the isolated canine femoral vein (1994)
    Springer
    Heart and vessels 9 (1994), S. 14-18 
    Details
    ISSN: 1615-2573
    Keywords: Prostacyclin ; Beraprost sodium ; Canine femoral vein ; Thromboxane A2/endoperoxide receptor ; Partial agonist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The vascular contractile mechanism of prostacyclin (PGI2) was investigated using beraprost sodium (BPS), a stable PGI2 analog. Ring strips without endothelium isolated from canine femoral veins and arteries were used. BPS induced a dose-dependent contraction without precontraction and after precontraction with norepinephrine (NE) or 60 mM K+ in the veins. In contrast, BPS induced a dose-dependent relaxation after precontraction with U46619, a thromboxane A2 (TXA2) analog, or prostaglandin F2α (PGF2α) in the veins. In the arteries, BPS induced contraction at higher concentrations after precontraction with NE. However, BPS relaxed arteries dose-dependently after precontraction with PGF2α. By pretreatment with 13-azaprostanoic acid (13-APA), a TXA2/endoperoxide receptor antagonist, the dose-response curve of BPS in the veins was shifted to the right. Schild plot analysis resulted in a linear regression with a slope of 0.86 ± 0.13, which was not significantly different from unity, and the pA2 value for 13-APA against BPS was 7.10 ± 0.06. By pretreatment with BPS, the dose-response curve of U46619 in the veins was shifted to the right. Kaumann plot analysis resulted in a linear regression with a slope of 0.89 ± 0.09, which was not significantly different from unity, and the pA2 value for BPS against U46619 was 5.68 ± 0.04. These findings indicate that BPS is a partial agonist for the TXA2/endoperoxide receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01744491
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of periodic change in pressure and dissolved-oxygen concentration on the incubation characteristics of Pseudomonas aeruginosa (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 663-667 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experiments were carried out to identify an efficient procedure for decreasing the amount of excess sludge in deep aeration columns. Incubation characteristics, especially cellular yield, are closely related to excess sludge, maximum specific growth rate, and chemical oxygen demand. They were measured here for the bacterium Pseudomonas aeruginosa, which tends to be predominant in sewage treatment, at a pressure remaining constant or periodically changing in the range of 1-6 atm (abs.). Cellular yields tended to decrease over 1-2 min pressure cycles; in steady operation they decreased considerably with increasing pressure or dissolved oxygen concentration. Maximum specific growth rates were moderately affected by periodic changes in pressure or dissolved oxygen concentration but markedly affected in the higher concentration range under steady operation. Substrate consumption rates on the other hand, were little affected in either case. The values of chemical oxygen demand ranged from 220 to 250 mg/L, and were thus nearly constant.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260280505
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    Paper (German National Licenses)
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