Lun Hsing Tung

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Celiprolol given intravenously (i.v.) to pithed rats in the dose range of 0.1-10,000 micrograms/g produced a dose-dependent increase in heart rate (HR) which was greatest (123 beats/min) at 1,000-3,000 micrograms/kg. This partial agonist effect was blocked by the selective beta 1-adrenoceptor antagonist CGP 20712A. Celiprolol also produced a vasodepressor(More)
Rats implanted with osmotic minipumps containing adrenaline (0.2 ml, 2.9 mM) developed increased systolic and diastolic blood pressures, whereas blood pressures in rats implanted with osmotic minipumps containing the same amount of noradrenaline did not differ from those of sham-operated control rats. Heart rates did not differ from control in either(More)
1. Rats implanted with osmotic minipumps delivering adrenaline intraperitoneally at the rate of 2.9 nmol/h had significantly higher systolic and diastolic pressures from days 2 to 6 after implantation than sham-operated controls rats. 2. Concomitant treatment with metoprolol tartrate (2.5 mg/kg, intraperitoneally, twice daily) prevented the elevation in(More)
1 Adrenaline (10 nM) significantly enhanced the stimulation-induced efflux of radioactivity from rat atria previously incubated with [3H]-noradrenaline ([3H]-NA). This effect was abolished by metoprolol (.01 muM). 2 Adrenaline in a higher concentration (1 muM) and NA (1 muM) significantly reduced the stimulation-induced efflux of radioactivity. However, in(More)
Phenylephrine, adrenaline, and noradrenaline have been shown to act on both alpha- and beta-adrenoceptors to produce an increase in heart rate in the pithed rat and rat isolated atria. Abolition of these responses requires blockade of both types of adrenoceptors. The rank order of alpha-adrenoceptor agonists to produce positive chronotropic responses was(More)
It is not surprising that there has been a search for compounds that combine two useful antihypertensive properties. The expectation is that one such product will offer a simple once-a-day control of blood pressure in a large portion of the population who require drug therapy for their disease. The major disadvantages of the first drug in this class,(More)
Positive chronotropic responses of rat isolated atria to phenylephrine were reduced by propranolol (0.3 microM) and the residual response was further depressed by the selective alpha 1-adrenoceptor antagonist prazosin (1 nM) but not yohimbine (10 nM), confirming that a component of the response to phenylephrine was due to activation of alpha(More)