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Biomedical subjects

B Szabo

Publications and source records attributed to B Szabo.

60 records · Page 4Linked to original sources
PubMed1986

Dopamine1 receptor agonist and alpha-2 adrenoceptor antagonist effects of fenoldopam in rabbits.

Neurochemical and circulatory effects of fenoldopam were studied in pithed rabbits with electrically stimulated sympathetic outflow and in strips of the rabbit pulmonary artery. In pithed rabbits, fenoldopam (1-30 micrograms/kg/min) decreased the arterial blood pressure. Fenoldopam (3-30 microgram/kg/min) also increased the norepinephrine spillover rate (the rate at which endogenous norepinephrine enters into the plasma after having been released from postganglionic sympathetic nerves) and decreased the [3H]norepinephrine plasma clearance. The selective dopamine (DA)1 antagonist SCH 23390 (bolus injection of 10 micrograms/kg followed by infusion of 2 micrograms/kg/hr) antagonized markedly and the DA2-selective antagonist domperidone (bolus injection of 200 micrograms/kg followed by infusion of 50 micrograms/kg/hr) antagonized slightly the hypotensive effect. The increase in the norepinephrine spillover rate was enhanced after treatment with desipramine. Clonidine (0.3 microgram/kg/min) reduced the spillover of norepinephrine, and this effect was abolished by fenoldopam (30 micrograms/kg/min). In pulmonary artery strips preincubated with [3H]norepinephrine, fenoldopam (10(-7) and 10(-6) M) increased the electrically evoked overflow of tritium. The effect of fenoldopam (10(-6) M) was prevented in the presence of a supramaximal concentration of clonidine (10(-5) M). The results suggest that fenoldopam lowers blood pressure mainly by activation of vascular smooth muscle DA1 receptors. In addition, however, it blocks prejunctional alpha-2 autoreceptors at postganglionic sympathetic axons.

Adrenergic alpha-Antagonists↗
PubMed1984

Thermoluminescent dose measurements on-board Salyut type orbital stations.

A small, vibration- and shock-resistant thermoluminescent dosemeter /TLD/ system--named PILLE--was developed at the Health Physics Department of the Central Research Institute for Physics, Budapest, to measure the cosmic radiation dose on board orbital stations. The first on-board measurements with this system were performed /by B. Farkas, the Hungarian astronaut/, on the Salyut-6 space station in 1980. The same instrument was used by other crews in the following years. Doses measured at different sites in Salyut-6 are presented. The dose rates varied from 0.07 to 0.11 mGy.day-1. After the first cosmic measurements, the system was further developed. The minimum detectable dose of the new TLD system is 1 microGy, i.e. less by on order of magnitude than that of the former system. The self-irradiation dose rate of the TLD bulbs is also reduced--by more than one order of magnitude--to 10 nGy.h-1, by the use of potassium-free glass for the bulb envelope. This new type of PILLE TLD system is currently on-board Salyut-7. The dose rates /0.12-0.23 mGy.day-1/ measured in 1983 are presented in detail.

Evaluation Studies as Topic↗
PubMed1981

A new thermoluminescent dosimeter system for space research.

A small, portable, vibration and shock resistant thermoluminescent dosimeter system was developed to measure cosmic radiation dose on board a spacecraft. The system consists of a small battery-operated reader and a special bulb dosimeter. Doses from 10 microGy up to 100 mGy can be measured. The electrical power consumption of the reader is about 5 W, its volume is about 1 dm3 and its mass is about 1 kg. Details are given for the construction and technical parameters of the dosimeter and reader.

Calcium Sulfate↗
PubMedDate not supplied

Bremazocine causes sympatho-inhibition and hypotension in rabbits by activating peripheral kappa-receptors.

We have studied the effects of bremazocine on the peripheral sympathetic nervous system and the arterial blood pressure of pithed rabbits with electrically (2 Hz) stimulated sympathetic outflow, and compared them with the effects of Leu-enkephalin and fentanyl. The 3H-noradrenaline plasma clearance and the plasma concentration of noradrenaline were used to calculate the rate of spillover of endogenous noradrenaline into the plasma; the spillover rate reflects the overall release of noradrenaline from postganglionic sympathetic neurones. Bremazocine (10 and 100 micrograms kg-1, followed by an infusion of 2 and 20 micrograms kg-1 h-1, respectively, i.v.) persistently decreased the noradrenaline spillover rate as well as blood pressure. Both effects were antagonized by naloxone. Leu-enkephalin (70 and 350 micrograms kg-1 min-1 i.v.) caused only transient hypotension. Fentanyl decreased blood pressure only at a very high dose (250 micrograms kg-1, followed by an infusion of 500 micrograms kg-1 h-1 i.v.). The effects of Leu-enkephalin and fentanyl were also antagonized by naloxone. When the blood pressure of pithed rabbits was raised by an intravenous infusion of noradrenaline, rather than by electrical stimulation, bremazocine, Leu-enkephalin, and fentanyl failed to produce hypotension. The results indicate that bremazocine inhibits the release of noradrenaline and, in consequence, lowers arterial pressure by activation of peripheral, probably prejunctional, opioid receptors. The receptors appear to be of the kappa-type.

Analgesics↗