Biomedical subjects

C F Chen

Publications and source records attributed to C F Chen.

At least 217 records · Page 12Linked to original sources

PubMed1995

DL-tetrahydropalmatine-produced hypotension and bradycardia in rats through the inhibition of central nervous dopaminergic mechanisms.

The effects of DL-tetrahydropalmatine (THP; a main active substance of the Chinese herb corydalis), haloperidol (a dopamine D2 receptor antagonist), apomorphine and amphetamine on cardiovascular function and striatal dopamine (DA) release were compared in rats under general anesthesia. Intravenous administration of THP (1-10 mg/kg) or haloperidol (0.5-1.25 mg/kg) produced hypotension, bradycardia and increased DA release in the striatum. On the other hand, amphetamine (0.5-1.25 mg/kg) produced hypertension, tachycardia and increased striatal DA release. However, intravenous injection of apomorphine (0.5-1.25 mg/kg) produced hypotension, bradycardia and decreased striatal DA release. In addition, the THP-induced hypotension was attenuated by pretreatment with spinal transection or amphetamine, while the THP-induced bradycardia was attenuated by pretreatment with bilateral vagotomy or amphetamine. Thus, it appears that THP acts through DA D2 receptor antagonism to induce hypotension and bradycardia in rats.

Amphetamine↗

PubMed1995

Disintegrin modulates rat glomerular mesangial cell behavior.

Disintegrins are a group of molecules containing Arg-Gly-Asp (RGD) sequence which can interfere with cell-matrix interaction. Rat mesangial cells are known to express an RGD-sensitive integrin receptor. We investigate the effect of a potent disintegrin, triflavin, on rat mesangial cell adhesion and proliferation. While synthetic RGD-containing peptide (GRGDS) inhibits mesangial cell adhesion to fibronectin, type I and type III collagen, triflavin has a similar but much more potent effect. Triflavin, when added to the medium, inhibits serum-stimulated rat mesangial cell proliferation in both growing and growth-arrested cells. In serum-free medium, platelet-derived growth factor promoted mesangial cell growth is also inhibited by triflavin. When coated as a substratum, both GRGDS and triflavin inhibit mesangial cell growth. The inhibition of proliferation by exogenously added triflavin and GRGDS is, at least in part, due to their antiadhesive effect. We conclude that triflavin can modulate both adhesion and proliferation of rat mesangial cells.

Amino Acid Sequence↗

PubMed1995

Vasodilator agents modulate rat glomerular mesangial cell growth and collagen synthesis.

Mesangial cell activation and extracellular matrix accumulation are hallmarks of many forms of glomerulonephropathy. We investigated the effect of several agents possessing vasodilating activities on rat mesangial cell growth and collagen synthesis. Using cell counting and a modified MTT assay, it was shown that dipyridamole, pentoxifylline, dicentrine, prazosin and doxazosin all caused a dose-dependent inhibition of serum-stimulated rat mesangial cell proliferation. Platelet-derived growth factor-induced cell proliferation was also inhibited by doxazosin and pentoxifylline. Dipyridamole and pentoxifylline inhibited collagen synthesis in confluent mesangial cells while dicentrine and doxazosin did not. The procollagen alpha 1 (I) mRNA expression was also decreased by dipyridamole and pentoxifylline. These results suggested that, in addition to dipyridamole, pentoxifylline and alpha 1-adrenoceptor blockers may have a potential to delay the progression of chronic glomerulopathy associated with mesangial proliferation.

Analysis of Variance↗

PubMed1995

Hypotensive and bradycardic effects of dl-tetrahydropalmatine mediated by decrease in hypothalamic serotonin release in the rat.

In anesthetized rats, intravenous administration of dl-tetrahydropalmatine (dl-THP, 1-10 mg/kg) elicited proportional hypotension, bradycardia and decreases in hypothalamic serotonin (5-HT) release (measured by carbon-fiber electrodes in combination with voltammetry). In addition, postsynaptic blockade of 5-HT2 receptors with cyproheptadine (2-5 mg/kg, i.v.) or ketanserin (2-5 mg/kg, i.v.) produced both hypotension and bradycardia, while stimulation of 5-HT2 receptors with 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) (10-250 mg/kg, i.v.) produced both hypertension and tachycardia. The dl-THP-induced hypotension and bradycardia could be reversed by DOI treatment. The data indicate that dl-THP decreases both arterial pressure and heart rate through a serotonergic release process in the hypothalamus.

Adrenergic Agents↗

PubMed1995

Evaluation with receptor binding assay on the water extracts of ten CNS-active Chinese herbal drugs.

In the present study, we established receptor binding assays to evaluate the water extracts of ten central nervous system (CNS)-active Chinese herbal drugs. These ten herbal drugs are Chaihu (Radix Bupleuri), Chuanxiong (Rhizoma Chuanxiong), Danggui (Radix Angelicae sinensis), Danshen (Radix Salviae miltiorrhizae), Duhuo (Radix Angelicae pubescentis), Hangqin (Radix Scutellariae), Qinjiao (Radix Gentianae macrophyllae), Shengma (Rhizoma Cimicifugae), Suanzaoren (Semen Zizphi spinose), and Yangjihua (Flos Daturae). The results indicated that these water extracts contained the principles acting on the dopamine (D1 & D2), muscarinice acetylcholine (M1), or 5-HT (5-HT1A & 5-HT2) receptors, or the benzodiazepine and the gamma-amino-n-butyric acid (GABA) binding sites of GABAA receptors as determined by receptor binding assays. The receptors or binding sites which predominantly acted by each water extract are listed as follows: Chaihu: D2, 5-HT1A, GABA; Chuanxiong: GABA, 5-HT1A; Danggui: GABA, 5-HT1A; Danshen: BDZ; Duhuo: GABA, 5-HT1A, D2, D1; Hangqin: BDZ, D1, 5-HT1A; Qinjiao: GABA, BDZ, 5-HT1A, D2; Shengma: 5-HT1A; Suanzaoren: 5-HT1A, 5-HT2, GABA; Yangjihua: M1, 5-HT1A, 5-HT2. These results provided evidence to explain the CNS effects of these herbal drugs at the receptor level. Furthermore, these results provided information to direct the isolation and purification of receptor-interactive compounds from these herbal drugs.

Animals↗

PubMed1995

The interaction of the neuromuscular effects between mivacurium and esmolol in rats.

BACKGROUND: To study the neuromuscular interaction between mivacurium and esmolol, we compared the neuromuscular actions of the ED90 dose of mivacurium both in the absence and presence of esmolol infusion. METHODS: Twelve rats were anesthetized with urethane. Train-of-four stimulation was applied every 12 s to the sciatic nerve, and the electromyogram (EMG) response of the anterior tibial muscle was measured. RESULTS: The ED50 and ED90 of mivacurium in rats were 144 +/- 7.3 micrograms/kg and 197 +/- 7.7 micrograms/kg, respectively. The maximal EMG depression produced by ED50 of mivacurium decreased significantly with esmolol treatment from 88.2 +/- 2.7% to 83.1 +/- 2.6% after esmolol infusion (p < 0.05). The onset time for 75% EMG depression was much shorter for control (44 +/- 6.3 s) than that of esmolol treatment (78.2 +/- 2.4 s; p < 0.05). There was no difference between their duration. CONCLUSIONS: The results of this study demonstrated that esmolol does not potentiate the neuromuscular effect of mivacurium but antagonize the maximal neuromuscular block and decrease its onset time in rats.

Adrenergic beta-Antagonists↗

PubMed1995

Effects of aprotinin on renal function in chronic hypoxic rats.

The effect of aprotinin, a nonspecific kallikrein inhibitor on renal function was studied in chronic hypoxic rats (high altitude, HA), comparing to control rats kept at sea level (SL). Hypoxia was induced by placing female Wistar rats (195-230 g) in an altitude chamber (5,500 m) 15 hr per day for 4 weeks. Intrarenal arterial administration of aprotinin (300 kiu/kg/min), reduced the urinary kallikrein activity (UKA) in 9 SL and 10 HA anesthetized rats. Aprotinin did not significantly alter the urinary excretion of urine, sodium and potassium in SL rats, however, those parameters increased after aprotinin administration in HA rats. These data support the hypothesis that kallikrein participates in the regulation of renal function in chronic hypoxic rats.

Altitude↗

PubMed1994

Role of renal nerves on renal functional change after back heating in the rat.

This study was designed to investigate the possible role of renal nerves in the regulation of renal function after the application of heat (BH), by means of an electric heating pad (42 +/- 1 degree C) to the skin of the back overlying the kidneys. Both renal efferent (RENA) and renal afferent nervous activity (RANA) were recorded in 7 anesthetized female Wistar rats. It was found that RENA reduced to less than 80% of the control level during 30 min of back heating, accompanied by an increase in excretion of urine, sodium and potassium, and enhanced the glomerular filtration rate. BH in 9 chronic bilateral renal denervated rats (RD) showed the same renal responses as in the renal nerve intact rats (RI) after back heating. It is concluded that renal nerves played only a partially role in the renal diuretic action of back heating.

Animals↗

PubMed1994

The mechanism of the vasodilator effect of rutaecarpine, an alkaloid isolated from Evodia rutaecarpa.

The mechanisms underlying the rutaecarpine-induced vasodilatation were studied using isolated rat mesenteric arterial ring segments. The results showed that rutaecarpine (0.1 microM to 0.1 mM) produced a dose-dependent vasorelaxing response in our preparations, which were precontracted with phenylephrine. This vasodilator effect was significantly attenuated by removal of the endothelium, treatment with L-NG-nitro-arginine, a nitric oxide synthase inhibitor, and methylene blue, a guanylyl cyclase inhibitor, but not by treatment with atropine, triprolidine and yohimbine. Rutaecarpine pretreatment (1 microM to 0.1 mM) reduced both the phasic (fast) and tonic (slow) phases of phenylephrine-induced contractions, suggesting that a reduction in intracellular calcium might be involved. It is thus concluded that while the vasorelaxing effect of rutaecarpine appeared to be endothelium-dependent and to involve nitric oxide and guanylyl cyclase, neither muscarinic receptors, histamine H1 receptors nor alpha 2-adrenoceptors are involved. Moreover, a direct effect on the vascular smooth muscle cell, possibly through a reduction in intracellular Ca2+, can not be excluded.

Acetylcholine↗

PubMed1994

Pharmacokinetics of honokiol after intravenous administration in rats assessed using high-performance liquid chromatography.

A simple and sensitive high-performance liquid chromatographic method for the identification and determination of honokiol in rat plasma has been developed. Up to 0.1 ml of plasma containing honokiol was deproteinized with acetonitrile, which contained an internal standard (paeonol). The supernatant was injected onto a reversed-phase C18 column using acetonitrile-water (70:30, v/v, adjusted to pH 2.5-2.8 with orthophosphoric acid) as the mobile phase and ultraviolet detection at 290 nm, followed by UV spectrum identification (between 220 and 380 nm) with a photodiode-array detector. The method was applied to pharmacokinetic studies of honokiol in rat following 5 or 10 mg/kg intravenous administration. A biphasic process consisting of a rapid distribution phase followed by a slower elimination phase was observed from the plasma concentration-time curves. Compartmental analysis yielded a two-compartment model.

Animals↗

PubMed1994

High-performance liquid chromatographic determination of rutaecarpine in rat plasma: application to a pharmacokinetic study.

A simple and sensitive high-performance liquid chromatographic method for determination and identification of rutaecarpine in rat plasma has been developed. Up to 0.1 ml of plasma containing rutaecarpine was deproteinized by acetonitrile, which contained an internal standard (paeonol). The supernatant was injected onto a reversed-phase column using a acetonitrile-water-orthophosphoric acid (85%) (60:40:0.1, v/v/v, pH 2.5-2.8) as the mobile phase and ultraviolet detection at 344 nm. It was applied to the pharmacokinetic study of rutaecarpine in rat after a 2 mg/kg intravenous administration. A biphasic process with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve. Compartmental analysis yielded a two-compartment model.

Acetophenones↗

PubMed1994

Rapid measurement of the monoamine content in small volumes of rat plasma.

A method for the simultaneous measurement of serotonin, catecholamines, and their metabolites, 5-hydroxy-indoleacetic acid, homovanillic acid, and 3, 4-dihydroxyphenylacetic acid, by ultrafiltration and microbore high-performance liquid chromatography with dual electrochemical detection in small plasma volumes was established. Unlike the traditional assays which require at least 1-2 ml of plasma for each measurement, the present method uses only a 20-microliters sample volume. Since blood loss is minimal, repeated blood sampling from a single animal as a rat becomes practicable. The present microassay provides low detection limits (signal-to-noise ratio = 3) for all analytes (0.2-0.5 pg per 5-microliters injection or 50-120 pg/ml plasma). Isocratic separation of these analytes on a microbore column is achieved within 15 min. This rapid and sensitive method can be used as a routine research tool in various physiological or pharmacokinetic studies especially in small animals.

Animals↗

PubMed1994

Magnolol and honokiol isolated from Magnolia officinalis protect rat heart mitochondria against lipid peroxidation.

In isolated rat heart mitochondria lipid peroxidation was induced with ADP and ferrous sulfate (FeSO4). Oxygen consumption and malondialdehyde (MDA) production were measured to quantitate lipid peroxidation. The antioxidant effects of magnolol and honokiol purified from Magnolia officinalis were 1000 times higher than that of alpha-tocopherol. The IC50 values of magnolol and honokiol for inhibition of oxygen consumption were 8.0 x 10(-8) M and 1.0 x 10(-7) M, respectively, while that of alpha-tocopherol was 1.0 x 10(-4) M. Magnolol at 0.5 microM inhibited 71.4 +/- 9.4% of oxygen consumption and 59.3 +/- 4.6% MDA production. At the same concentration, honokiol inhibited 78.1 +/- 4.7% of oxygen consumption and 86.9 +/- 4.0% of MDA production. Of conjugated diene formation 48.4 +/- 4.6% and 53.1 +/- 3.4% were inhibited by 0.5 microM magnolol and honokiol, respectively. Also both magnolol and honokiol exhibited free radical scavenging activities as shown by the diphenyl-p-picrylhydrazyl assay, but they were less potent than alpha-tocopherol.

Animals↗

PubMed1994

Simultaneous measurement of acetylcholine and monoamines by two serial on-line microdialysis systems: effects of methamphetamine on neurotransmitters release from the striatum of freely moving rats.

A rapid and sensitive set-up consisting of a microbore HPLC with electrochemical detection coupled with two serial on-line microdialysis systems was described to simultaneously measure endogenous levels of acetylcholine (ACh), choline (Ch), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 3-methoxytyramine (3-MT), 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) in freely moving rats. The validity of the present procedure is demonstrated by analyzing the effect of methamphetamine (2 mg/kg, s.c.) on the increase release of DA, 3-MT, 5-HT, and ACh but without effect in Ch, DOPAC, HVA and 5-HIAA from the striatum of freely moving rat.

Acetylcholine↗

PubMed1994

Pharmacokinetics of paeonol after intravenous administration in rats.

A simple high-performance liquid chromatography methodology was developed to study the pharmacokinetics of paeonol in the rat after intravenous (iv) bolus administration of various doses (2.5, 5, or 10 mg/kg). The pharmacokinetics of paeonol in rat plasma at each dose were well described by a two-compartment model. The area under the curve increased proportionally with dose and consequently total body clearance was independent of dose. There was no dose-related difference in the elimination half-life or volume of distribution. These results indicate that the pharmacokinetics of paeonol after iv administration are linear over the 2.5-10 mg/kg dose range.

Acetophenones↗

PubMed1994

Two new macrolide sesquiterpene pyridine alkaloids from Maytenus emarginata: emarginatine G and the cytotoxic emarginatine F.

Two new macrolide sesquiterpene pyridine alkaloids, emarginatine F [1] and emarginatine G [2], were isolated from Maytenus emarginata. The structural determinations of 1 and 2 by 2D nmr techniques and spectral comparison with a related compound, emarginatine A [3], are discussed. Biological evaluation showed that emarginatine F [1] demonstrated strong cytotoxicity against human epidermoid carcinoma of the nasopharynx (KB), ileocecal adenocarcinoma (HCT-8), melanoma (RPMI-7951) and medulloblastoma (TE-671) tumor cells, and against murine leukemia (P-388).

Animals↗

PubMed1994

Effect of the crude extract of Evodiae Fructus on the intestinal transit in mice.

One of the uses of Evodiae Fructus (EF, the dried, unripe fruit of Evodia rutaecarpa) in Chinese medicine is recommended in diarrhea, but its underlying mechanism has not yet been studied. The present study examined the effect of an aqueous extract of EF on the intestinal transit in mice by the charcoal meal method. Intraperitoneal administration (i.p.) of EF (1.9-30 g/kg) significantly inhibited the intestinal transit in a dose- and time-dependent manner. This inhibitory effect of EF was not attenuated by the i.p. pretreatment with an alpha 2-, alpha 1-, or beta-adrenoceptor antagonist, i.e. yohimbine (10 mg/kg), prazosin (2 mg/kg), or propranolol (6 mg/kg), respectively. In the isolated mouse duodenum, jejunum, and ileum preparations, EF (10-50 mg/ml) concentration-dependently abolished 10 microM carbachol-induced contraction with an IC50 of 9.9, 11.7, and 16.3 mg/ml, respectively. This inhibitory effect was not competitive. Receptor binding assay showed that EF (1-50 mg/ml) significantly competed with [3H]-N-methylscopolamine for specific binding to muscarinic receptors on the duodenum, jejunum, and ileum membrane preparations with a Ki value of 7.1, 8.4, and 14.4 mg/ml, respectively. Therefore, the above results suggested that the inhibitory effect of EF on intestinal transit was probably via an action directly on the muscarinic receptors but not on the alpha 2, alpha 1-, and beta-adrenoceptors in the small intestine.

Animals↗

PubMed1994

Purification of phospholipase C from rat cerebral cortex.

Phospholipase C from rat cerebral cortex was purified to homogeneity by use of DEAE Bio-Gel A agarose, hydroxyapatite, and heparin agarose chromatography. The purified phospholipase C (PLC) was purified 622.4-fold and its molecular weight is estimated to be 97,500. We obtained a final specific activity of 3.112 mumol of phosphatidylinositol hydrolyzed/min/mg of protein. It is specific for inositol phospholipids. The purified enzyme has an apparent optimum pH 7.0. Calcium is required for its activity. Western blotting analysis showed that two proteins were recognized by anti-PLC antiserum.

Animals↗