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  • 1
    Electronic Resource
    Electronic Resource
    CIRCULATING Na+/K+-ATPase INHIBITORS: EFFECTS OF NEUROPEPTIDES, VOLUME EXPANSION AND SALT LOADING IN CONSCIOUS RATS (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 24 (1997), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. In mammalian plasma, many different inhibitors of Na+/K+-ATPase are present, but it is not clear whether their net effect on Na+/K+-ATPase activity changes during the regulation of electrolyte and fluid balance. We studied Na+/K+-ATPase inhibition by plasma extracts in conscious rats during short-and long-term body fluid regulation.2. Male, adult, conscious, freely moving Wistar rats were subjected to one of the following protocols: (i) intracerebroventricular (i.c.v.) injections of angiotensin II (Angll; 1, 10 and 100 ng), the Angll receptor antagonist losartan (1μg), atrial natriuretic peptide (ANP-III; 1μg) or isotonic saline (IS); (ii) intra-arterial (i.a.) injections of IS (6 or 10 mL), hypertonic saline (HS; 1.2% NaCl, 5 mL) or hypertonic plasma expander (HPS; 3.5% hetastarch in HS, 5mL); or (iii) a low salt-high salt-low salt diet sequence (0.18/1.8/0.18% NaCl chow for S days each with controls receiving 0.18% NaCl on all days). Bodyweight, the intake of food and water, urine volume and Na+ concentration and weight of faeces were determined daily. Plasma samples were withdrawn repeatedly throughout the respective protocols, extracted on C18-reversed phase columns and assayed for their effect on the activity of different Na+/K+-ATPase preparations.3. The inhibition of rat brain Na+/K+-ATPase by plasma extracts was not significantly changed by i.c.v. injection of Angll, losartan, ANP-III and IS within the observation period (30 min from respective stimuli). Similarly, no significant changes occurred after acute volume expansion by i.a. injection of IS or HS within 120 min; upon HPS, however, Na+/K+-ATPase inhibition was decreased by approximately 20% (P〈0.05), probably due to passive dilution. During the high-salt diet, fluid retention was effectively counteracted by an adaptive increase of urinary sodium excretion. Throughout the protocol, inhibition of pig brain Na+/K+-ATPase by plasma extracts did not differ significantly between groups.4. It is concluded from these results that the short- or long-term control of body fluids in conscious rats is not associated with systematic changes in Na+/K+-ATPase inhibition by plasma factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1997.tb01795.x
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  • 2
    Electronic Resource
    Electronic Resource
    Role of the native kidney in experimental post-transplantation hypertension (1996)
    Springer
    Pflügers Archiv 431 (1996), S. 971-976 
    Details
    ISSN: 1432-2013
    Keywords: Blood pressure ; Hypertension ; Kidney Renal ; transplantation ; Spontaneously hypertensive ; rat99mTechnetium-mercaptoacetyltriglycine scintigraphy ; Wistar-Kyoto rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In experimental renal transplantation studies using several animal models of primary hypertension, including stroke-prone spontaneously hypertensive rats (SHRSP) and their normotensive Wistar-Kyoto controls (WKY), single transplanted kidneys from genetically hypertensive but not normotensive donors elicited post-transplantation hypertension in bilaterally nephrectomized genetically normotensive recipients. The underlying mechanisms are presently unclear. The present study was designed to investigate the effects of a remaining native kidney on post-transplantation blood pressure, plasma renin activity and plasma angiotensin II concentration in (WKY×SHRSP) F1 hybrid recipients of a WKY or SHRSP kidney. The presence of a native kidney markedly reduced, but did not prevent, post-transplantation hypertension in recipients of an SHRSP kidney. WKY kidney grafts did not significantly alter blood pressure in bilaterally or unilaterally nephrectomized recipients. Plasma renin activity was lower in bilaterally than in unilaterally nephrectomized recipients, regardless of the source of the graft. The plasma angiotensin II concentration was similar in all groups. Renal graft function as assessed by99mtechnetium-mercaptoacetyltriglycine scintigraphy was well preserved. These data suggest that post-transplantation hypertension in recipients of an SHRSP kidney may be partly due to the failure of the graft to eliminate a hypertensinogenic substance or to produce a blood pressure lowering agent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02332185
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  • 3
    Electronic Resource
    Electronic Resource
    The insertion/deletion polymorphism of the angiotensin-converting enzyme gene and the risk for restenosis after PTCA (2000)
    Springer
    The international journal of angiology 9 (2000), S. 82-86 
    Details
    ISSN: 1615-5939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The therapeutic benefit of percutaneous transluminal coronary angioplasty (PTCA) is limited by restenosis in about 30% of patients. The underlying mechanisms are currently not well understood. Besides clinical and angiographic variables, genetic factors may be involved. We determined the angiotensin I-converting enzyme (ACE) I/D genotype as a possible risk factor for restenosis in 511 consecutive patients who had undergone successful PTCA and follow-up angiography. Clinical and angiographic variables were also considered as possible predictors of restenosis. One hundred sixty patients had restenosis as defined by a greater than 50% progression of residual stenosis of the dilated segment at follow-up angiography. There were significantly more patients with the ACE DD genotype in the restenosis than in the no-restenosis group. This difference did not remain statistically significant in an analysis of covariance that included genetic and clinical variables. Patients who subsequently developed restenosis had a higher degree of stenosis and more severe lesions before PTCA as well as less residual stenosis immediately after PTCA. We conclude that the ACE DD genotype is not an independent risk factor for restenosis after PTCA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01617046
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  • 4
    Electronic Resource
    Electronic Resource
    Immobilisierbare stabilisatoren für EPDM-kautschuk (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 211 (1993), S. 165-194 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: For the application as immobilized antioxidants in ethylene-propylene-diene terpolymers (EPDM), 2-mercapto-N-[4-phenylamino)phenyl]-acetamide (MADA) and 2,2′-dithiobis[N-(4-phenylamino)phenyl]-acetamide (DAPA) were synthesized and characterized. The reactions of these antioxidants with EPDM rubbers were simulated with the model compounds trans-4-decene, 2-ethylidene norbornane, and tricyclo-[5.2.1.02,6]-3-decene. The reaction products were separated by chromatography and characterized by infrared spectroscopy. The effect of azo initiators on the immobilization reaction was studied.The reaction of EPDM with the above-mentioned stabilizers was studied in a Brabender Plastograph in the mass temperature range 140 to 180°C. The content of immobilized stabilizer was determined by thermoanalysis and UV spectroscopy. The highest degrees of immobilization (73%) were achieved with MADA at 180°C. DAPA could be immobilized up to maximum 69%. The applicability of immobilization of the stabilizers on EPDM rubber was confirmed with cable sheathing compounds crosslinked by electron irradiation.
    Notes: Als immobilisierbare Antioxidantien für Ethylen-Propylen-Dien-Terpolymere (EPDM) wuren 4-(Mercaptoacetamido)-diphenylaminSystematischer Name: 2-Mercapto-N-[4-phenylamino phenyl]-acetamid. (MADA) und Dithiodiglycolsäure-bis-[N-(4-anilinophenyl-amid]Systematischer Name: 2,2′-Dithiobis[N-(4-phenylamino)phenyl]-acetamid. (DAPA) hergestellt und charakterisert. Zur Simulation der Reaktionen bei der Umsetzung dieser Antioxidantien mit EPDM-Kautschuken wurden Modellreaktionen mit trans-4-Decen, 2-Ethylidennorbornan und 2,3-DihydrodicyclopentadienSystematischer Name: Tricyclo[5.2.1.02,6]-3-decen. durchgeführt. Die Reaktionsprodukte wurden chromatorgraphisch aufgetrennt und durch IR-Spektroskopie charakterisiert. Dabei wurde auch der Einfluß von Azoinitiatoren auf die Additionsreaktion untersucht.Die Umsetzung von EPDM mit den genannten Stabilisatoren wurde im BrabenderPlastographen bei 140 bis 180°C Massetemperatur untesucht. Der Gehalt an immobilisiertem Stabilisator wurde mit Hilfe der Thermoanalyse und UV-spektroskopisch bestimmt. Die höchsten Gehalte an immobilisiertem Stabilisator (73%) wurden mit MADA bei 180°C Massetemperatur erzielt. DAPA ist ebenfalls bis maximal 69%immobilisierbar. Die praktische Baruchbarkeit der Immobilisierung von Mercaptostabilisatoren an EPDM-Kautschuk wurde am Beispiel von strahlenvernetzten Kabelisoliermassen bestätigt.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052110115
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  • 5
    Electronic Resource
    Electronic Resource
    Central angiotensin II stimulates arteriolar vasomotion in conscious hamsters (1989)
    Springer
    Journal of comparative physiology 159 (1989), S. 577-582 
    Details
    ISSN: 1432-136X
    Keywords: Arterioles ; Vasomotion ; Angiotensin II ; Vasopressin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of intracerebroventricular (icv) injections of 10 ng angiotensin II (ANG II) on mean arteriolar diameter and spontaneous arteriolar vasomotion were studied in subcutaneous tissue of conscious, restrained hamsters, using the skin fold window chamber preparation. Angiotensin II caused a significant decrease in mean arteriolar diameter which was associated with a significant elevation in the amplitude of vasomotion. The frequency of vasomotion did not change significantly. The central ANG II-induced effects on arteriolar vasomotion were not significantly altered by continuous intravenous (iv) infusion of hexamethonium (1 mg · kg−1 · min−1). In contrast, iv bolus injection of the vascular vasopressin receptor antagonist d(CH2)5Tyr(Me)AVP (10 μg · kg−1) 5 min prior to icv injection of ANG II significantly attenuated the effects of the neuropeptide on mean arteriolar diameter and the amplitude of vasomotion. These data indicate that central ANG II stimulation enhances arteriolar vasomotion in peripheral subcutaneous tissue of conscious hamsters and that this effect may be mediated by release of vasopressin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694382
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  • 6
    Electronic Resource
    Electronic Resource
    Central effects of angiotensin II in conscious hamsters: drinking, pressor response, and release of vasopressin (1989)
    Springer
    Journal of comparative physiology 158 (1989), S. 703-709 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of intracerebroventricular (icv) injections of angiotensin II (ANG II) on water intake, blood pressure, heart rate, and plasma arginine-vasopressin (AVP) concentration were studied in chronically instrumented adult male Syrian golden hamsters (Mesocricetus auratus). Furthermore, the effects of pharmacological ganglionic blockade, and of vascular AVP receptor blockade, on central ANG II-induced cardiovascular responses were investigated. ANG II (1, 10, and 100 ng, icv) elicited dose-dependent increases in water intake and arterial blood pressure. Heart rate showed a biphasic response with a short initial non dose-dependent tachycardic and a subsequent longer lasting bradycardic phase. Plasma AVP concentration was increased two and a half fold with 100 ng ANG II icv. Both ganglionic blockade and vascular AVP receptor blockade significantly attenuated the central ANG II-induced pressor response. The tachycardic phase of the heart rate response was abolished by ganglionic blockade and the bradycardic phase was significantly diminished by AVP receptor blockade. The results support the hypothesis that brain ANG II may participate in the central control of body fluid volume and in central cardiovascular regulation in conscious hamsters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00693008
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