• Journal of Yeungnam Medical Science
• /
• v.26 no.2
• /
• pp.93-101
• /
• 2009

The use of magnesium sulphate has recently increased in anesthesiology and pain medicine. The roles of magnesium sulphate are as an analgesic adjuvant, a vasodilator, a calcium channel blocker and reducing the anesthetic requirement. These effect are primarily based on the regulation of calcium influx into the cell and antagonism of the N-methyl-D-aspartate receptor. We discuss here the clinical effects of magnesium sulphate on anesthesiology and pain medicine.

• Archives of Pharmacal Research
• /
• v.29 no.9
• /
• pp.777-785
• /
• 2006

Nelumbinis Semen (NS), or lotus seed, is one of the most well-known traditional herbal medicines and is frequently used to treat cardiovascular symptoms in Korea. The anti-ischemic effects of NS on ischemia-induced isolated rat heart were investigated through analyses of changes in blood pressure, aortic flow, coronary flow, and cardiac output. The subjects in this study were divided into two groups: a control, untreated ischemia-induced group, and an ischemia-induced group treated with NS. There were no significant differences in perfusion pressure, aortic flow, coronary flow and cardiac output between the groups before ischemia was induced. The supply of oxygen and buffer was stopped for ten minutes to induce ischemia in isolated rat hearts, and NS was administered during ischemia induction. NS treatment significantly prevented decreases in perfusion pressure, aortic flow, coronary flow and cardiac output under ischemic conditions (p<0.01). In addition, the mechanism of the anti-ischemic effects of NS was also examined through quantitation of intracellular calcium content in rat neonatal cardiomyocytes. NS significantly prevented intracellular calcium increases induced by isoproterenol (p<0.01). These results suggest that NS has distinct anti-ischemic effects through calcium antagonism.

• YAKHAK HOEJI
• /
• v.31 no.6
• /
• pp.376-393
• /
• 1987

This study was performed in order to investigate the effect of nifedipine, a vasodilating drug which acts through calcium antagonism, on renal function using mongrel dog. Nifedipine, when given interavenously in doses ranging from 1.5 to 5.0$\mu\textrm{g}$/kg, elicited diuresis along with less changes of glomerular filtration rate and significant increases of renal plasma flow, so that the filtration fraction(FF) decreased significantly, at the same time both osmolar and free water clearances increased, and amount of sodium, potassium and calcium excreted in urine increased significantly. Nifedipine, when infused into a renal artery in doses from 0.05 to 0.15$\mu\textrm{g}$/kg/min, exhibited identical responses to the actions of intraveneous nifedipine except significant increase of glomerular filtration rate and no change of FF, which was confined only to the infused kidney. The renal action of nifedipine into a renal artery were not influenced by renal denervation, decreased significantly by ouabain, Na$^+$-K$^+$-ATPase inhibitor, which was given into a renal artery. Nifedipine infused into a renal artery in dog pretreated with propranolol i.v. produced diuresis associated with the increase of electrolytes excretion by reduction of electrolyte reabsorption and with no changes of glomerular filtration rate and renal plasma flow. Thus, it is concluded that nifedipine infused into a renal aretery produces diuretic action along with both improvement of hemodynamics and inhibition of electrolytes reabsorption, which may be related to sympathetic $\beta$-receptor or Na$^+$-K$^+$-ATPase activity because the action of nifedipine in kidney is blocked by propranolol or ouabain.

• Natural Product Sciences
• /
• v.5 no.1
• /
• pp.25-32
• /
• 1999

The pharmacological actions of ambrein were investigated alone or in combination as a pretreatment with agonists (adrenaline, noradrenaline, acetylcholine, histamine, nicotine), antagonists (atropine, atenolol) and calcium channel blocker (verapamil) in vivo in anaesthetized SWR rats using blood pressure, heart rate and myocardial contractility as parameters. Ambrein in the dose range of 50-200 mg/kg to the normotensive anaesthetized rats demonstrated negative chronotropic effect and increased the myocardial contractility significantly. At the mid dose (100 mg/kg) this increase in contractile force was 36% and 44% above the normal at 30 min and 60 min intervals post-treatment, respectively. Both of the lower and high doses (50 mg/kg and 200 mg/kg) had similar effects. Furthermore, this contractile response was dose related. Also, this compound produced a considerable increase in myocardial contractility when used as a pretreatment with some agonists and antagonists. The results on blood pressure did not show a considerable change when ambrein was used alone. However, ambrein pretreatment at the dose of 100 mg/kg did not block the effects of adrenaline, noradrenaline, isoprenaline and acetylcholine on heart rate and blood pressure. On the other hand, this pretreatment attenuated the sympathoadrenal effects of nicotine significantly. Chronotropic and blood pressure changes produced by histamine were also inhibited by ambrein pretreatment. This pretreatment significantly reversed the effects of atenolol but failed to demonstrate any change in the negative chronotropic, inotropic and hypotensive responses induced by verapamil. It is concluded that ambrein induced nonselective dose dependent antagonism of the effects of some agonists and antagonists require contribution of some neuromediators. However, the positive isotropic effects of ambrein possibly involve the enhancement of slow Ca channels and/or activation of ${\beta}-adrenergic$ receptors in the heart. At this moment it is difficult to explain the exact mode of action of ambrein and the studies dealing with Ca channel blocker and adrenergic blocker followed by ambrein may help to define the factors which contribute to its positive inotropic effects.

• International Journal of Oral Biology
• /
• v.36 no.2
• /
• pp.71-78
• /
• 2011

Using whole cell current- and voltage-clamp recording we investigated the characteristics and pharmacology of group I metabotropic glutamate receptor (mGluR)-mediated responses in rat medial vestibular nucleus (MVN) neurons. In current clamp conditions, activation of mGluR I by application of the group I mGluR agonist (R,S)-3,5-dihydroxyphenylglycine (DHPG) induced a direct excitation of MVN neurons that is characterized by depolarization and increased spontaneous firing frequency. To identify which of mGluR subtypes are responsible for the various actions of DHPG in MVN, we used two subtype-selective antagonists. (S)-(+)- alpha-amino-a-methylbenzeneacetic acid (LY367385) is a potent competitive antagonist that is selective for mGluR1, whereas 2-methyl-6-(phenylethynyl)-pyridine (MPEP) is a potent noncompetitive antagonist that is selective for mGluR5. In voltage clamp conditions, DHPG application increased the frequency of spontaneous and miniature inhibitory postsynaptic currents (IPSCs) but had no effect on amplitude distributions. Antagonism of the DHPG-induced increase of miniature IPSCs required the blockade of both mGluR1 and mGluR5. DHPG application induced an inward current, which can be enhanced under depolarized conditions. DHPG-induced current was blocked by LY367385, but not by MPEP. Both LY367385 and MPEP antagonized the DHPG-induced suppression of the calcium activated potassium current ($I_{AHP}$). These data suggest that mGluR1 and mGluR5 have similar roles in the regulation of the excitability of MVN neurons, and show a little distinct. Furthermore, mGluR I, via pre- and postsynaptic actions, have the potential to modulate the functions of the MVN.

• Korean Journal of Environment and Ecology
• /
• v.17 no.2
• /
• pp.144-152
• /
• 2003

The purpose of this study was to investigate the effects of lime fertilization and light intensity on beech regeneration strategy in a mature beech forest(ca. 150 years old) gaps, which was located in the soiling areas Germany, where the soil is an acid brown earth. For the experiment canopy gaps of 30m diameter were cut, and one canopy gap remained as untreated while the other was limed(3t dolomite h $a^{-1}$). Soil chemistry, soil water potential, light intensity(PAR), ground vegetation, beech seedlings and mycorrhiza were investigated along transect from the stands into gaps to the north. The results of this study are followings: 1) In the limed gap, soil chemistry was greatly improved and a vigorous herb layer developed as compared to the unlimed gap. 2) Development and growth of the beech seedlings in the unlimed gap were generally deficient. Specially, developments of lateral roots were very lack. 3) Through the lime fertilization, the minerals contents of beech leaves such as calcium(Ca) and magnesium(Mg) were increased, while manganese(Mn) was decreased. There was antagonism between potassium(K) and calcium(Ca) or magnesium(Mg). 4) The relative mycorrhiza frequency(RM) in beech seedlings of the southern edge was very higher than that of the middle part, and through the lime fertilization extension of the species Laccaria amethystina appeared clearly. The results of this study showed that lime fertilize in forest, where the soil is acid, will be necessary..

• Horticultural Science & Technology
• /
• v.30 no.1
• /
• pp.27-33
• /
• 2012

This study aimed to investigate the responses of plant growth and blossom-end rot (BER) incidence to calcium (Ca) and its three kinds of antagonistic cations (K, Mg, and $NH_4$-N) with various ratios in nutrient solution for sweet paper (Capsicum annuum L. 'RZ208'). Both Ca to each cation and Ca to a series of cation combinations, such as potassium (K), ammonium nitrate ($NH_4$), or magnesium (Mg) were more influential to the fruit growth and quality than plant growth. Especially, the BER incidence was significantly influenced by the ratio treatments. For examples, when Ca:(K + Mg) or Ca:(K + Mg + $NH_4$) ratio was 1:2 the highest incident rate of BER about 70.3 or 86.3% was observed, lowering the marketable yield to 19 or 13.7% of the total yield, respectively. The correlation coefficiencies (= r) to relationships between the BER and K as well as BER and $NH_4$ were 0.82 (P < 0.05) and 0.65 (P < 0.05), respectively. Combination only with the Mg element was not correlated with the BER incidence. However, when both of the K and Mg concentrations were 0.65 (P < 0.05). The highest correlation coefficiency, 0.92 (P < 0.05), was found to a relationship between the BER and the tree elemental combination.

• Tuberculosis and Respiratory Diseases
• /
• v.40 no.1
• /
• pp.16-22
• /
• 1993

Background: The Microbicidal and cytotoxic activities of neutrophils are to a large extent dependent on a burst of oxidative metabolism which generates superoxide anion, hydrogen peroxide, and other reactive products of oxygen. The respiratory burst of PMN is initiated by intracellular calcium mobilization that follows immune or particular stimulation and is very sensitive to modulation by c-AMP or adenosine. Despite its antagonism against adenosine, earlier study has demonstrated potent theophylline inhibition of the PMN respiratory burst at variable ranges of blood concentrations of theophylline in the healthy normal volunteers and in the septic animals pretreated or early post-treated with aminophylline (AMPH) or pentoxifylline. However it is unclear whether theophylline inhibits the superoxide generation or not in the established human sepsis caused by acute pneumonia, as taking into consideration of the fact that full activation of neutrophils have occurred within minutes after the septic insult in the animal experiments. Methods: We measured the $O_2$ generation of peripheral arterial neutrophils obtained from 11 human septic subjects caused by acute pneumonia before and 1 hour after completion of continuous AMPH infusion. Patients were identified and studied within 48 hour of admission. All subjects were administered an intravenous loading and maintenance dose of AMPH. The generation of $O_2$ was measured at a discrete time point (60 min) by the reduction of ferricytochrome c.PMA (10 ${\mu}g/ml$) was used as a stimulating agent. PMNs were isolated at a concentration of $2{\times}10^6$ cells/ml. The arterial oxygen tension, blood pressure and heart rates were also checked to evaluate the systemic effects of AMPH in the acute pneumonia. Results: The mean serum concentration of AMPH at 60 minutes was $8.8{\pm}0.6{\mu}g/ml$. Sixty minutes after AMPH infusion the generatition of $O_2$ was decreased from $0.076{\pm}0.034$ to $0.013{\pm}0.004$(OD) (p<0.05) and from $0.177{\pm}0.044$ to $0.095{\pm}0.042$(OD) (p<0.01) in the resting and stimulated PMNs respectively. $PaO_2$ was not changed after AMPH infusion. Conclusion: AMPH may compromise host defense by significant inhibition of neutrophil release of superoxide anion and it had no effect on improving $PaO_2$ in the acute pneumonia.