OBJECTIVETo investigate the vasodilating effects of pethidine, particularly in association with intracellular calcium.

METHODSAorta rings of Sprague-Dawley rats, with or without endothelium, were prepared in organ bath to measure the vascular tone. Pre-contractions by KCl (80 mmol/L) and phenylephrine (PhE) (10(-6)mol/L) were induced.

RESULTSPethidine did not alter the resting tension of aorta rings, but produced dose-dependent relaxation in KCl and PhE pre-treated aorta rings with or without endothelium. Pethidine did not change the caffeine-stimulated contraction, and still had similar inhibition in KCl pre-contracted aorta rings after pretreatment with ruthenium red. Pethidine decreased the contractile responses induced by PhE in Ca(2+)-free solution or by adding calcium into Ca(2+)-free solution.

CONCLUSIONPethidine could produce an endothelium-independent vasodilatation in KCl and PhE pre-contracted aorta rings, which is related to inhibition of Ca(2+)entry and IP3-sensitive Ca(2+) release in vascular smooth muscle.

Animals ; Caffeine ; pharmacology ; Calcium ; metabolism ; Male ; Meperidine ; pharmacology ; Potassium Chloride ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Vasodilator Agents ; pharmacology

AIMTo observe the effects of ouabain on vascular smooth muscle (VSM) of the guinea pig and its interactions with Ca2+ and norepinephrine (NE).

METHODSUsing isolated thoracic aortic ring of the guinea pig, the degrees of contractile activity of drugs were recorded.

RESULTSOuabain showed a direct contractile effect in a concentration-dependent manner on thoracic aortic ring of guinea pig. Ouabain shifted the NE dose-response curve to the left without changing in the maxium response. Ouabain shifted the CaCl2 dose-response curve to the left and upward, increased the maximum response to Ca2+; In Ca(2+)-free medium, the ouabain induced contraction was abolished, an increase in extracellular Ca2+ restored the response; nifedipine and verapamil abolished the ouabain induced contraction.

CONCLUSIONThe ouabain induced contraction is mainly dependent on the extracellular Ca2+ concentration, independent on the presence of endothelia of aorta, suggesting that Ca2+ antagonist may treat the hypertension induced by ouabain. Ouabain, NE and CaCl2 have synergetic contractile effects, suggesting that the synergetic contractile effects of ouabain and NE may contribute to the generation and development of hypertension.

Animals ; Aorta, Thoracic ; drug effects ; Calcium ; metabolism ; Calcium Channel Blockers ; pharmacology ; Calcium Chloride ; pharmacology ; Drug Synergism ; Female ; Guinea Pigs ; Male ; Muscle Contraction ; drug effects ; Muscle, Smooth, Vascular ; drug effects ; Nifedipine ; pharmacology ; Norepinephrine ; pharmacology ; Ouabain ; pharmacology ; Verapamil ; pharmacology

Hyaluronan (HA), a natural glycoaminoglycan featuring an extracellular matrix, has been suggested as an effective biocompatible material. In this study, the effectiveness of HA microparticles as a carrier system for antibiotics was evaluated, and their physicochemical characteristics were determined. Microparticles were fabricated by the gelation of sulfadiazine (SD) loaded HA solution with calcium chloride through either a granulation (GR-microparticles) or encapsulation (EN-microparticles) process, and atelocollagen was incorporated into the microparticles as an additive in order to improve their physical properties. The characteristics of the microparticles were examined by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and swelling test. In vitro release experiments were performed for 7 days and the released amount of SD was determined using high-performance liquid chromatography (HPLC). Microscopic observations revealed that the collagen incorporated HA particles had a more compact surface than the HA particles. DSC analysis determined a loss of SD crystallinity in the particles. Calcium chloride retarded the swelling of particles, whereas the loaded drug contents did not affect this property. Both GR-and EN-microparticles sustained SD release with initial bursting effect. SD release from EN-microparticles was faster than from GR- microparticles. In addition, the release rate was dependent on the SD content in the microparticles. These results suggest that collagen modified HA microparticles have a potential as a release rate controlling material for crystalline drugs such as SD.
Antibiotics/*administration & dosage ; Calcium Chloride/pharmacology ; Collagen/*pharmacology ; *Drug Carriers ; Hyaluronic Acid/*administration & dosage ; Sulfadiazine/administration & dosage

OBJECTIVETo investigate the effect and mechanism of Huanglian Jiedu Tang active fraction (HIJDTAF) on calcium overloading in neurons.

METHODCerebral ischemia was imitated by hypoxia/hypoglycemia damage on fetal rat neurons. Double wavelength fluorospectrophotometry was used to assay the content of calcium in neurons in order to evaluate the effect of HLJDTAF on calcium overloading. Neurons were treated with glutamic acid, potassium chloride (KCl), A23187, caffeine(CAF) and methacholine (Mch) to analysis the related mechanism of HLJDTAF on calcium overloading in neurons.

RESULTHLJDTAF 0.3, 0.15 g x k(-1) could remarkably inhibit the calcium overloading in neurons caused by hypoxia/hypoglycemia, glutamic acid, KCl and A23187. HLJDTAF 0.3 g x kg(-1) could inhibit the increasing of calcium caused by CAF and Mch in the presence of and in the absence of extra-calcium.

CONCLUSIONHLJDTAF could remarkably inhibit the calcium overloading in neurons after cerebral ischemia injury, it probably plays the function via several pathways.

Animals ; Caffeine ; pharmacology ; Calcimycin ; pharmacology ; Calcium ; metabolism ; Cells, Cultured ; Drugs, Chinese Herbal ; pharmacology ; Glutamic Acid ; pharmacology ; Male ; Methacholine Chloride ; pharmacology ; Neurons ; cytology ; drug effects ; metabolism ; Potassium Chloride ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Spectrometry, Fluorescence

OBJECTIVETo study the vasodilation effect of the procyanidin (PC) extracted from grape seeds on rabbit thoracic aortic rings in vitro, decreasing blood pressure in vivo and the possible mechanism.

METHODRabbits aortic rings were isolated and were divided into six groups including removal of endothelium, integrity of endothelium, 1 x 10(-5) mol X L(-1) indomethacin (Indo), 1 x 10(-5) mol x L(-1) propranolol (Prop), 1 x 10(-4) mol x L(-1) N(omega)-nitro-L-arginine (L-NNA) and 1 x 10(-5) mol x L(-1) methylene blue (MB). Then the thoracic aortic rings were treated with PC with cumulative concentrations of 1.25, 2.5, 5.0 mg x L(-1) respectively and the changes of tension were recorded, and investigate the effect of 40 mg x L(-1) PC on the contraction of aortic smooth muscles, thoracic aortic rings were pre-treated with NA (1 x 10(-8) to approximately 1 x 10(-5) mol x L(-1)), KCl (6.3 to approximately 100 mmol x L(-1)) and CaCl2 (1 x 10(-5) to approximately 1 x 10(-5) mol x L(-1)) followed by treatment with PC. Then, rabbits common carotid artery was intubated and arterial blood pressure in vivo was recorded. PC with cumulative concentrations of 4.0, 8.0, 16, 32, 64, 84 mg x kg(-1) was injected into vein and the changes of arterial blood pressure were observed.

RESULTPC could relax isolated rabbit aorta and showedan obvious concentration-dependent relaxation (r = 0. 63, P < 0.001). The relaxant effect of PC was significantly reduced by removal of endothelium and by treatment with nitric oxide synthase inhibitor L-NNA, or guanylyl cyclase inhibitor MB. In addition PC could decrease the dose response curves of aortic rings to NA, KCl and CaCl2. PC has a significant concentration-dependent negative effect on arterial blood pressure in vivo (r = 0.92, P < 0.001).

CONCLUSIONPC has a vasodilation effect not only in an endothelium-dependent, nitric oxide involved manner, but in inhibition of calcium release and blockage of potential-dependent calcium channels. PC could decrease the rabbit's arterial blood pressure significantly in vivo.

Animals ; Aorta ; drug effects ; physiology ; Calcium Chloride ; pharmacology ; Female ; In Vitro Techniques ; Male ; Muscle Contraction ; drug effects ; Muscle Relaxation ; drug effects ; Muscle, Smooth, Vascular ; drug effects ; Norepinephrine ; pharmacology ; Potassium Chloride ; pharmacology ; Proanthocyanidins ; pharmacology ; Rabbits ; Vasodilator Agents ; pharmacology

AIMTo study the relaxation mechanisms of tetrandrine (Tet) on the corpus cavernosum smooth muscle.

METHODSThe corpus cavernosum smooth muscle cells from New Zealand white rabbits were cultured in vitro. [Ca(2+)](i) was measured by Fluorescence Ion Digital Imaging System, using Fluo-2/AM as a Ca(2+)-sensitive fluorescent indicator.

RESULTSTet (1, 10 and 100 micromol/L) had no effect on the resting [Ca(2+)](i) (P>0.05). In the presence of extracellular Ca(2+) (2.5 mmol/L), Tet (1, 10 and 100 micromol/L) inhibited [Ca(2+)](i) elevation induced by high K(+) and phenylephrine (PE) in a concentration-dependent manner (P>0.05). In calcium free solution containing egtaic acid, Tet (1 and 10 micromol/L) had no inhibitory effects on [Ca(2+)](i) elevation induced by PE (P>0.05). However, Tet (100 micromol/L) inhibited [Ca(2+)](i) elevation induced by PE (P>0.05).

CONCLUSIONTet inhibited the Ca(2+) influx from the extracellular site via voltage-activated Ca(2+) channel and alpha(2)-adrenoceptor-operated Ca(2+) channel. At a high concentration, Tet might inhibit the cytosolic calcium pool release in cultured corpus cavernosum smooth muscle cells. This inhibitory action on [Ca(2+)](i) might be one of the relaxation mechanisms of Tet on the corpus cavernosum smooth muscle.

Alkaloids ; pharmacology ; Animals ; Benzylisoquinolines ; pharmacology ; Calcium ; metabolism ; Cytosol ; drug effects ; metabolism ; Male ; Muscle Relaxation ; Muscle, Smooth, Vascular ; cytology ; metabolism ; Penis ; cytology ; metabolism ; Phenylephrine ; pharmacology ; Potassium Chloride ; pharmacology ; Rabbits

AIMTo investigate the role of calcium-activated chloride channels and the Cl- channel blockers niflumic acid (NFA) and indanyloxyacetic acid (IAA-94) in the regulation of vascular contraction induced by phenylephrine (PE).

METHODSThe PE-induced contraction in rat pulmonary artery was observed by using routine blood vascular perfusion in vitro. The fluorescence Ca2+ indicator Fura-2/AM was used to observe intracellular free Ca2+ concentration ([Ca2+]i) of rat pulmonary artery smooth muscle cells (PASMCs) which were obtained by the acute enzyme separation method (collagenase I plus papain) on NFA and IAA-94 effects on PE-induced contraction. Changes of [Ca2+]i in PASMCs were measured by spectrofluorometry.

RESULTSThe anion channel blockers NFA and IAA-94 produced inhibitory effects on PE-induced contractions in the pulmonary artery. NFA and IAA-94 negligibly affected the KCl-induced pulmonary artery contractions. PE could increase [Ca2+]i but NFA and IAA-94 negligibly affected it.

CONCLUSIONCalcium-activated chloride channels contribute to the agonist-induced pulmonary artery contractions under physiological conditions, which may be a new clue to investigate the hypoxic pulmonary vasoconstriction.

Animals ; Calcium ; physiology ; Chloride Channels ; physiology ; Glycolates ; pharmacology ; Male ; Muscle, Smooth, Vascular ; physiology ; Niflumic Acid ; pharmacology ; Phenylephrine ; pharmacology ; Pulmonary Artery ; physiology ; Rats ; Rats, Sprague-Dawley ; Vasoconstriction

In this paper, membrane current properties of the fully-grown oocytes from toad, Bufo bufo gargarizans, were studied by using two-microelectrode voltage clamp technique. Axion of adult female toad was destroyed, and then ovarian lobes containing oocytes in stage I to VI were removed and incubated in Ca(2+)-free ND96 solution with collagenase (1.5 mg/ml) for 1 h. Subsequently, the oocytes were washed in Ca(2+)-free ND96 solution for 10 min to completely remove the follicular layer. For the experiments only the oocytes in stage V and VI were selected and used during 1 to 5 d. The membrane was depolarized from a holding potential of -80 mV to +60 mV in 10 mV step. It was found that a sustained outward current was elicited by depolarization. Potassium channel blockers (tetraethylammonium chloride, TEA, 10 mmol/L and 4-aminopyridine, 4-AP, 10 mmol/L) reduced the outward current to (23.4+/-0.72)% of the maximum. However, further addition of chloride channel blocker (5-nitro-2, 3-phenypropylamino benzoate, NPPB, 30 micromol/L) could almost completely block the outward current to (2.1+/-0.08)% of the maximum. In the presence of TEA and 4-AP, removal of extracellular Ca(2+) or adding verapamil (40 micromol/L), could also reduce the outward current to (2.2+/-0.04) % and (3.1+/-0.15) % of the maximum, respectively. It is concluded that calcium-dependent chloride channels exist in plasma membrane of Bufo bufo gargarizans oocytes, besides potassium channels.
4-Aminopyridine ; toxicity ; Animals ; Bufo bufo ; Calcium ; metabolism ; Cell Membrane ; metabolism ; Chloride Channels ; drug effects ; physiology ; Female ; Nitrobenzoates ; pharmacology ; Oocytes ; metabolism ; Tetraethylammonium Compounds ; pharmacology ; Verapamil ; pharmacology

OBJECTIVETo investigate the vasodilative effect of paeonol in rat mesenteric artery and the mechanisms responsible for it.

METHODSRats were anaesthetized and sacrificed. The superior mesenteric artery was removed, dissected free of adherent tissue and cut into 2.0 mm long cylindrical segments. Isometric tension of artery rings was recorded by a myograph system in vitro. Concentration-relaxation curves of paeonol (17.8 μ mol/L to 3.16 mmol/L) were recorded on artery rings precontracted by potassium chloride (KCl) and concentration-contraction curves of KCl, 5-hydroxytryptamine (5-HT), noradrenaline (NA) or calcium chloride (CaCl2) were recorded in the presence of paeonol (10(-4.5), 10(-3.8), 10(-3.5) mol/L) respectively. And also, concentration-relaxation curves of paeonol were recorded in the presence of different potassium channel inhibitors and propranolol on rings precontracted with KCl respectively. To investigate the role of intracellular Ca(2+) release from Ca(2+) store, the contraction induced by NA (100 μ mol/L) and CaCl2 (2 mmol/L) in Ca(2+) free medium was observed in the presence of paeonol respectively.

RESULTSPaeonol relaxed artery rings precontracted by KCl in a concentration-dependent manner and the vasodilatation effect was not affected by endothelium denudation. Paeonol significant decreased the maximum contractions (Emax) induced by KCl, CaCl2, NA and 5-HT, as well as Emax induced by NA and CaCl2 in Ca(2+) -free medium, suggesting that paeonol dilated the artery via inhibiting the extracellular Ca(2+) influx mediated by voltage-dependent calcium channel, and receptor-mediated Ca(2+)-influx and release. Moreover, none of glibenclamide, tetraethylammonium, barium chlorded and propranolol affected the paeonol-induced vasodilatation, indicating that the vasodilatation was not contributed to ATP sensitive potassium channel, calcium-activated potassium channel, inwardly rectifying potassium channel, and β-adrenoceptor.

CONCLUSIONPaeonol induces non-endothelium dependent-vasodilatation in rat mesenteric artery via inhibiting voltage-dependent calcium channel-mediated extracellular Ca(2+) influx and receptor-mediated Ca(2+) influx and release.

Acetophenones ; pharmacology ; Adrenergic beta-Antagonists ; pharmacology ; Animals ; Calcium ; metabolism ; Calcium Chloride ; pharmacology ; Endothelium, Vascular ; drug effects ; physiology ; Extracellular Space ; drug effects ; metabolism ; Female ; In Vitro Techniques ; Intracellular Space ; drug effects ; metabolism ; Male ; Mesenteric Arteries ; drug effects ; physiology ; Norepinephrine ; pharmacology ; Potassium Channel Blockers ; pharmacology ; Potassium Chloride ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Serotonin ; pharmacology ; Vasoconstriction ; drug effects ; Vasodilation ; drug effects

OBJECTIVETo observe the effect of Tiangou Jiangya capsule on isolated rabbit aortic strips, and to discuss its antihypertensive mechanism.

METHODThe isolated rabbit aortic strips were placed in perfusion baths, and induced to contract by norepinephrine (NE), KCl and CaCl2 respectively, then Tiangou Jiangya capsule extraction was added to observe its effect on the contraction. The effect on intracellular Ca2+ dependent contraction and extracellular Ca2+ dependent contraction induced by NE were also studied.

RESULTThe Tiangou Jiangya capsule (1, 3, 5 g x L(-1)) can reduce the largest contract reaction of aortic strips induced by NE or CaCl2 (P < 0.01). It can reduce both intracellular Ca2+ dependent contraction and extracellular Ca2+ dependent contraction induced by NE (P < 0.01), and the effect on extracellular Ca2+ dependent contraction is more significant. But the Tiangou Jiangya capsule has no significant effect on KCl induced contraction.

CONCLUSIONTiangou Jiangya capsule can regulate intracellular Ca2+ concentration and help to relax the vascular smooth muscle. The mechanism could be regulating the receptor-operated Ca2+ channel. The effect on extracellular Ca2+ dependent contraction is more obvious than on intracellular Ca2+ dependent contraction induced by NE.

Animals ; Antihypertensive Agents ; pharmacology ; Aorta ; drug effects ; Benzyl Alcohols ; pharmacology ; Blood Pressure ; drug effects ; Calcium Chloride ; pharmacology ; Diuresis ; drug effects ; Drugs, Chinese Herbal ; pharmacology ; Flavonoids ; pharmacology ; Furans ; pharmacology ; Glucosides ; pharmacology ; In Vitro Techniques ; Lignans ; pharmacology ; Male ; Muscle Contraction ; drug effects ; Muscle, Smooth, Vascular ; drug effects ; Norepinephrine ; pharmacology ; Potassium Chloride ; pharmacology ; Rabbits ; Renin-Angiotensin System ; drug effects ; Ventricular Function, Left ; drug effects