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  • 1
    ISSN: 0942-0940
    Keywords: Endothelin ; neuropeptide Y ; angiotensin II ; cerebral arteries ; cerebral circulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have studied the effect of endothelin, an endothelium-derived peptide, on isolated canine and bovine cerebral arteries in vitro and on canine vertebral blood flow (VBF) in vivo. Endothelin produced a dose-dependent contraction of canine and bovine arterial smooth muscle with ED50 values ranging from 4 to 8 nM. The response to endothelin developed slowly and persisted as a sustained contraction. Maximal contraction by endothelin required the presence of extracellular calcium and was independent of the presence of endothelium. The maximal contraction produced by endothelin was approximately 2–3 times greater than that produced by neuropeptide Y or angiotensin II. The injection of endothelin into the vertebral artery decreased vertebral blood flow (VBF) dose-dependently without affecting systemic blood pressure or heart rate. The decrease in VBF produced by endothelin was long-lasting, like that produced by neuropeptide Y, but more potent. The present data, together with our previous study demonstrating that the intracisternal injection of endothelin induces an unusually long-lasting decrease in the basilar artery diameter angiographically, suggests that endothelin may act as a long-acting vasoconstrictor in cerebral vascular disease.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Microsystem technologies 1 (1995), S. 143-148 
    ISSN: 1432-1858
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Technology
    Notes: Abstract A new type absolute-humidity sensor with very quick response, very small power consumption and high sensitivity, which is based on the detection of the thermal conductivity change in humid air at heated temperature above 400°C, has been developed and demonstrated. Since this new type absolute-humidity sensor is able to be easily heated up above 400°C within 30–40 msec because of a micro-air-bridge heater structure, the surface of its sensing area is refreshed by burning out adsorbed dusts, oil, etc. Thermal conductivity λmix of mixed gas expressed by Sutherland-Wassiljewa equation is applied to the humid air to study this absolute humidity sensor. Only a single micro-air-bridge heater operation driven by double pulse-currents for this humidity sensor is also proposed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1106
    Keywords: Axonal branching ; Vestibulo-ocular ; Vestibulo-collic ; Neck motoneurons ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Unit activities of 148 secondary vestibular neurons related to the posterior semicircular canal were recorded extracellularly in anesthetized cats. Axonal projections of these neurons were examined by their antidromic responses to stimulation of the excitatory target motoneurons of the contralateral (c-) inferior rectus muscle (IR) and bilateral (bi-) motoneuron pools of longus capitis muscles, neck flexors, in the C1 segment (C1LC). The neurons were classified into 4 groups according to their axonal projections. The first group of neurons, termed vestibulo-oculo-collic (VOC) neurons, sent axon collaterals both to the c-IR motoneuron pool and to the c-C1LC motoneuron pool. The majority of them (72%) were located in the descending nucleus. The second group of neurons were termed vestibuloocular (VO) neurons and sent their axons to the c-IR motoneuron pool but not to the cervical cord. Most of them (86%) were located in the medial nucleus. The third group of neurons, termed vestibulo-collic (contralateral) (VCc) neurons, sent axons to the cC 1LC motoneuron pool via the contralateral ventral funiculus but not to the oculomotor nuclei. They were mostly (75%) found in the descending nucleus. The last group of neurons were vestibulo-collic (ipsilateral) (VCi) neurons, which gave off axons to the ipsilateral (i-) C1LC motoneuron pool via the ipsilateral ventral funiculus but not to the oculomotor nuclei. One of them also sent an axon collateral to the c-C1LC motoneuron pool. The majority of them (74%) were located in the ventral part of the lateral nucleus. It was also observed in some of the VOC and VCi neurons that they produced unitary EPSPs in the c-C1LC and i-C1LC motoneurons, respectively. Their synaptic sites were estimated to be on the cell somata and/or proximal dendrites of the motoneurons.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1041
    Keywords: nilvadipine ; calcium antagonist ; essential hypertension ; antihypertensive drug ; stress ; cold pressor test ; haemodynamics ; plasma renin ; plasma noradrenaline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The immediate haemodynamic effects of the calcium antagonist nilvadipine have been studied in ten patients with established mild essential hypertension. Nilvadipine 4 mg p.o. reduced both the systolic and diastolic blood pressures within 60 min, associated with a fall in total peripheral resistance and an increase in heart rate and cardiac index. The peak of blood pressure and total peripheral resistance reached during a cold pressor test were reduced by nilvadipine, but it did not affect the haemodynamic responsiveness to cold stimulation. Plasma renin activity was unaltered and the plasma noradrenaline concentration was increased only slightly. Thus, nilvadipine lowered blood pressure at rest and during cold stimulation as a result of arteriolar dilatation. The hypotensive effect at rest was associated with a reflex increase in heart rate and cardiac index.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 42 (1992), S. 265-269 
    ISSN: 1432-1041
    Keywords: Nicardipine ; Hypertension ; calcium antagonist ; mental arithmetic ; cold pressor test ; exercise test ; haemodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of the calcium antagonist nicardipine on the pressor response to mental arithmetic, cold pressor and exercise tests have been studied in fifteen patients with established mild to moderate essential hypertension. Nicardipine 20 mg p.o. showed a hypotensive effect within 60 min, associated with a fall in total peripheral resistance and an increase in heart rate. As the pressor response to each stress was not affected by nicardipine, the peak blood pressure reached during each stress was lower. Nicardipine lowers blood pressure at rest as a result of arteriolar dilatation, associated with reflex tachycardia. The pressor responsiveness to various stresses was not affected by nicardipine.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1041
    Keywords: TZU-0460 ; renal failure ; H2-receptor antagonist ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We have studied pharmacokinetics of a new H2-receptor antagonist, TZU-0460, in patients with varying degrees of renal impairment. The apparent volume of distribution at steady-state was 1.70 l/kg, and the plasma protein binding of TZU-0460 or its active metabolite, desacetyl TZU-0460 was less than 10% in normal subjects. These variables were not altered with renal impairment. Sixty percent of TZU-0460 given orally was excreted via the kidney, mainly by tubular secretion. The half-time of elimination was 3.94 h in normal subjects, and was prolonged to 12.13 h in severe renal failure (creatinine clearance below 30 ml/min/1.48 m2). Dosage adjustment of TZU-0460 is necessary in renal failure.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1041
    Keywords: SUN 1165 ; renal failure ; antiarrhythmic agent ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of a new Class I antiarrhythmic agent, SUN 1165, has been studied in 32 patients with varying degrees of renal impairment following a single oral dose of 50 mg. The apparent volume of distribution at steady state was 1.48 1 · kg−1, the absorption rate constant was 2.2 h−1, and plasma protein binding was 26.8% in subjects with normal renal function. These variables were not altered with renal impairment. More than 60% of SUN 1165 given orally was excreted unchanged via the kidney, both by tubular secretion and glomerular filtration. The elimination rate constant, the apparent total body clearance and the apparent renal clearance were linearly correlated with the endogenous creatinine clearance. The half-time of elimination was 3.4 h in normal subjects and it was prolonged to 23.7 h in severe renal failure (creatinine clearance below 20 ml · min−1 · 1.48 m−2). Dosage adjustment of SUN 1165 is necessary in renal failure.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 45 (1993), S. 321-325 
    ISSN: 1432-1041
    Keywords: Manidipine ; Essential hypertension ; renal function ; glomerular hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The renal effects of manidipine hydrochloride were investigated in ten hospitalised patients with mild-to-moderate essential hypertension. After a one-week placebo period, manidipine was given for 1 week in a dose rising from 5 mg to 10 mg or 20 mg daily to normalise the mean blood pressure measured after 2 h. Blood pressure had decreased from 171/101 to 147/86 mm Hg at the end of manidipine treatment. The pulse rate was unaltered. Renal vascular resistance decreased from 1.90 to 1.33 dyn · s · cm−5/1.48 m2 × 104, and renal blood flow and glomerular filtration rate increased from 522 to 662 ml · min−1 · 1.48 m−2 and from 81 to 93 ml · min−1 · 1.48 m−2, respectively, in spite of a fall in renal perfusion pressure. Manidipine reduced the filtration fraction from 0.260 to 0.243, suggesting a preferential reduction in efferent arteriolar resistance. The fractional excretion of sodium and potassium did not change. Manidipine did not produce any significant alteration in plasma renin activity or in the plasma aldosterone concentration. The results indicate that manidipine has favourable renal effects and a concomitant hypotensive action in patients with mild-to-moderate essential hypertension.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0942-0940
    Keywords: Calcium antagonist ; chronic cerebral vasospasm ; HA 1077 ; subarachnoid haemorrhage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effectiveness of calcium antagonists on a chronic cerebral vasospasm after an SAH is still under debate. Calcium channel blockers such as nimodipine, nefedipine etc. can dilate spastic arteries by intrathecal administration, but not by systemic (iv or po) use. HA 1077 is a novel and potent calcium antagonist vasodilator which is considered to act by employing different mechanisms from the usual calcium channel blockers since it inhibits 1. calcium ionophore A 23187 induced contraction in arterial strips and 2. phenylephrine induced contraction in calcium free media, suggesting that its site of action is in the intracellular space. HA 1077 is water soluble and relatively stable in light. In the present study, the efficacy of HA 1077 was evaluated on dogs by using the spiral arterial strips in vitro and by angiography in vivo. In the arterial strips from the control dogs, a 50% relaxation of KCl (15 mM) induced contraction was obtained by a 10−6 M HA 1077 for the “intracranial” basilar and middle cerebral arteries, while a 10−5 M was needed to obtain the same effect for the “extracranial” common carotid and vertebral arteries, indicating that HA 1077 is more effective for the intracranial arteries. A vasospasm was produced by the “two haemorrhage” model of Varsoset al. The average angiographic diameter of the basilar artery was reduced to 60% of the control on SAH day 7. Intravenous infusion of HA 1077 (0.5–3 mg/kg/30 min) significantly dilated the spastic basilar artery (up to 20–30%), for over 2 hours. A fall in the systemic BP remained less than 20% during this time. Such spasmolytic effects by intravenous administration could not have been obtained with the usual calcium channel blockers. HA 1077 may be suitable for the treatment of a vasospasm in humans as well.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Archives of Biochemistry and Biophysics 271 (1989), S. 107-112 
    ISSN: 0003-9861
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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