This study was designed to observe the differences between main pulmonary arteries and the third-order branches of pulmonary arteries in the contractile response to phenylephrine (Phen), endothelin-1 (ET-1) and potassium chloride (KCl). The vascular tension changes of main and the third-order branches of pulmonary arteries induced by KCl, ET-1 and Phen were recorded by traditional vascular tone detection methods and microvascular ring technique, respectively. The results showed that Phen could cause a significant contraction in main pulmonary arteries, but did not induce apparent contraction in the third-order branches of pulmonary arteries. Compared with main pulmonary arteries, ET-1 contracted the third-order branches of pulmonary arteries with reduced maximal response value and PDvalue. In comparison with the main pulmonary arteries, contraction caused by KCl was enhanced in the third-order branches of pulmonary arteries. The results suggest that the vascular reactivity of main and the third-order branches of pulmonary arteries is different and it is important to study the vascular function of small branches of pulmonary arteries. This study could provide an important experimental basis for the further study on vascular function of small branches of pulmonary arteries and the functional changes in pulmonary hypertension.
Animals ; Endothelin-1 ; pharmacology ; Male ; Phenylephrine ; pharmacology ; Potassium Chloride ; pharmacology ; Pulmonary Artery ; drug effects ; Rats ; Vasoconstriction

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

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

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

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

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

AIMTo study unitary-core osmotic pump tablet for delivering water-insoluble drug for 24 hours.

METHODSUnitary-core osmotic pump tablet was prepared using nifedipine as the model drug. The effects of various core formulation variables on drug release were studied.

RESULTSPolyethylene oxide and potassium chloride have comparable positive effects on drug release, whereas, nifedipine has markedly negative effect on drug release.

CONCLUSIONUnitary-core osmotic pump tablet is very easy in preparation and it can deliver water-insoluble drug in substantially constant rate for 24 hours.

Calcium Channel Blockers ; administration & dosage ; chemistry ; Delayed-Action Preparations ; Drug Delivery Systems ; Nifedipine ; administration & dosage ; chemistry ; Osmosis ; Polyethylene Glycols ; pharmacology ; Potassium Chloride ; pharmacology ; Solubility ; Tablets ; Technology, Pharmaceutical ; methods

AIMTo observe the regulatory volume decrease (RVD) process of human intestine cells and investigate its ion channel mechanism.

METHODSCultured human intestine cells were exposed to hypotonic solution and the cell volume was measured using Coulter Counter System. RT-PCR was explored to detect the mRNA expression of Ca(2+) -activated K+ channel.

RESULTSHuman intestine cells showed a RVD process and this process could be blocked by Cl- channel blocker NPPB and K+ channel blocker TEA. Further results demonstrated the subtype of K+ channel involved in RVD was an intermediate-conductance, Ca(2+) -activated K+ channel (IK) because of its high sensitivity to clotrimazole. RT-PCR results also showed the expression of IK in this cell line.

CONCLUSIONThe RVD process of intestine cell was dependent on the parallel activation of Cl- channel and K+ channel. The subtype of K+ channel in volved in the RVD process was IK channel.

Cell Line ; Cell Size ; drug effects ; Chloride Channels ; antagonists & inhibitors ; metabolism ; Epithelial Cells ; cytology ; Humans ; Hypotonic Solutions ; Intestine, Small ; cytology ; Potassium Channel Blockers ; pharmacology ; Potassium Channels ; metabolism ; Potassium Channels, Calcium-Activated ; metabolism

OBJECTIVETo select an effective way to enhance vigor of Prunella vulgaris seeds.

METHODThree population seeds were treated at the 20 degrees C and dark enviroment.

RESULTPriming with 20% - 30% PEG and 200 - 400 mg x L(-1) GA3 could enhance seeds germination and vigor. Germination percentage of three population seeds treated with 0. 6% - 3.0% NaCl reduced, but they started to germinate in advance. Treated with 0.6% - 2.4% KNO3-KH2PO4, germination rate and vigor of seeds in Zijinshan and Pan' an both increased and the one in Bozhou decreased.

CONCLUSIONVigor of P. vulgaris seed treated with PEG and GA3 under proper concentration increases, while treated with KNO3-KH2PO, and NaCl low vigor seeds germination rate reduces.

Darkness ; Germination ; drug effects ; radiation effects ; Gibberellins ; pharmacology ; Nitrates ; pharmacology ; Phosphates ; pharmacology ; Polyethylene Glycols ; pharmacology ; Potassium Compounds ; pharmacology ; Prunella ; drug effects ; physiology ; radiation effects ; Seeds ; drug effects ; radiation effects ; Sodium Chloride ; pharmacology ; Temperature

AIMTo investigate the relaxation mechanisms of neferine (Nef) on the rabbit corpus cavernosum tissue in vitro.

METHODSStrips of rabbit corpus cavernosum were mounted in organ chambers. The effects of Nef were examined on isolated muscle strips precontracted with phenylephrine (PE) alone, in the presence of N(W)-nitro-L-arginine (LNNA, a nitric oxide synthase inhibitor), 1-H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one (ODQ, a guanylyl cyclase inhibitor), indomethacin (cyclooxygenase inhibitor), tetraethylammonium (Ca(2+)-activated K(+) channel blocker), 4-aminopiridine (4-AP, voltage dependent K(+) channel blocker) and glibenclamide (ATP sensitive K(+) channel blocker). The effects of Nef on KCl-induced contraction of isolated muscle strips were also investigated. The procedure of calcium absence-calcium addition was designed to observe the effect of Nef on two components of the contractile responses to PE based on the source of Ca(2+) (extracellular vs. intracellular).

RESULTSCorpus cavernosum strips relaxed in response to Nef (10(-9)-10(-4) mol/L) in a concentration-dependent manner with an IC(50) of 4.60 X 10(-6) mol/L. However, they were not affected by LNNA, ODQ, indomethacin or K(+)-channel blockers. Nef (10(-6) mol/L, 10(-5) mol/L) concentration dependently reduced the maximal contraction response of isolated strips induced by KCl to 79.3%+/-5.5% and 61.5%+/-3.2%, respectively (P < 0.01). In the calcium absence-calcium addition procedure, Nef 10(-5) mol/L inhibited both intracellular calcium-dependent and extracellular calcium-dependent contraction induced by PE (2 X 10(-5) mol/L) (P < 0.05). The inhibition ratios were 26.2%+/-5.4% and 48.3%+/-7.6%, respectively.

CONCLUSIONThe results of the present study suggest that Nef possesses a relaxant effect on rabbit corpus cavernosum tissues, which is attributable to the inhibition of extracellular Ca2+ influx and the inhibition of release of intracellular stored Ca(2+), but not mediated by the release of nitric oxide, prostaglandins or by the activation of potassium channels.

Animals ; Benzylisoquinolines ; pharmacology ; Calcium ; pharmacology ; Dose-Response Relationship, Drug ; Drugs, Chinese Herbal ; pharmacology ; Male ; Muscle Contraction ; drug effects ; Muscle Relaxation ; drug effects ; Penis ; drug effects ; physiology ; Phenylephrine ; pharmacology ; Potassium Chloride ; pharmacology ; Rabbits ; Vasoconstrictor Agents ; pharmacology