The carotid sinus baroreceptor reflex (CSR) is an important approach for regulating arterial blood pressure homeostasis instantaneously and physiologically. Activation of the central histaminergic or cholinergic systems results in CSR functional inhibitory resetting. However, it is unclear whether two systems at the nucleus tractus solitarius (NTS) level display cross interaction to regulate the CSR or not. In the present study, the left or right carotid sinus region was isolated from the systemic circulation in Sprague-Dawley rats (sinus nerve was reserved) anesthetized with pentobarbital sodium. Respective intubation was conducted into one side isolated carotid sinus and into the femoral artery for recording the intracarotid sinus pressure (ISP) and mean arterial pressure (MAP) simultaneously with pressure transducers connection in vivo. ISP was set at the level of 0 mmHg to eliminate the effect of initial internal pressure of the carotid sinus on the CSR function. To trigger CSR, the ISP was quickly elevated from 0 mmHg to 280 mmHg in a stepwise manner (40 mmHg) which was added at every step for over 4 s, and then ISP returned to 0 mmHg in similar steps. The original data of ISP and corresponding MAP were fitted to a modified logistic equation with five parameters to obtain the ISP-MAP, ISP-Gain relationship curves and the CSR characteristic parameters, which were statistically compared and analyzed separately. Under the precondition of no influence on the basic levels of the artery blood pressure, the effects and potential regulatory mechanism of preceding microinjection with different cholinoceptor antagonists, the selective cholinergic M1 receptor antagonist, i.e., pirenzepine (PRZ), the M2 receptor antagonist, i.e., methoctramine (MTR) or the N1 receptor antagonist, i.e., hexamethonium (HEX) into the NTS on the changes in function of CSR induced by intracerebroventricular injection (i.c.v.) of histamine (HA) in rats were observed. Meanwhile, the actions and possible modulatory mechanism of preceding microinjection with different histaminergic receptor antagonists, the selective histaminergic H1 receptor antagonist, i.e., chlorpheniramine (CHL) or the H2 receptor antagonist, i.e., cimetidine (CIM) into the NTS on the changes in function of CSR resulted from the i.c.v. cholinesterase inhibitor, physostigmine (PHY) were also examined in order to confirm and to analyze effects of cross interaction between central histaminergic and cholinergic systems on CSR. The main results obtained are as follows. (1) Standalone microinjection of different selective cholinergic receptor antagonists (PRZ, MTR or HEX) or different selective histaminergic receptor antagonists (CHL or CIM) into the NTS with each given dose had no effects on the CSR function and on the basic levels of the artery blood pressure, respectively (P > 0.05). (2) The pretreatment of PRZ or MTR into the NTS with each corresponding dose could attenuate CSR resetting resulted from i.c.v. HA in some degrees, which remarkably moved the posterior half range of ISP-MAP relationship curve downwards (P < 0.05), shifted the middle part of ISP-Gain relationship curve upwards (P < 0.05), and increased reflex parameters such as the MAP range and maximum gain (P < 0.05), but decreased parameters such as saturation pressure and intracarotid sinus pressure at maximum gain (P < 0.05). The catabatic effects of pretreatment with MTR into the NTS on CSR resetting induced by i.c.v. HA were more obvious than those with PRZ (P < 0.05), but pretreatment of HEX with given dose into the NTS had no effects on CSR resetting induced by i.c.v. HA (P > 0.05). (3) The effects of pretreatment of CHL or CIM into the NTS with each corresponding dose on CSR resetting made by i.c.v. PHY were similar to those of pretreatment of PRZ or MTR into the NTS on CSR resetting resulted from i.c.v. HA, and the decreasing effects of pretreatment with CHL into the NTS on CSR resetting induced by i.c.v. PHY were more remarkable than those with CIM (P < 0.05). These findings suggest that CSR resetting resulted from either HA or PHY into the lateral ventricle may partly involve the descending histaminergic or cholinergic pathway from the hypothalamus to NTS, which might evoke a cross activation of the cholinergic system in the NTS, via cholinergic M1 and M2 receptors mediation, especially the M2 receptors showing actions, or trigger another cross activation of the histaminergic system in the NTS, by histaminergic H1 and H2 receptors mediation, especially the H1 receptors displaying effects.
Animals ; Baroreflex ; Carotid Sinus ; physiology ; Chlorpheniramine ; pharmacology ; Cholinergic Antagonists ; pharmacology ; Cimetidine ; pharmacology ; Histamine ; pharmacology ; Pressoreceptors ; physiology ; Rats ; Rats, Sprague-Dawley ; Solitary Nucleus ; physiology

To establish single- and double-transfected transgenic cells stably expressing hMATE1, hMATE1 cDNA was cloned by RT-PCR from human cryopreserved kidney tissue, and subcloned into pcDNA3.1(+) plasmid by virtue of both HindIII and Kpn I restriction enzyme sites. Subsequently, the recombined pcDNA3.1(+)- hMATE1 plasmid was transfected into MDCK, MDCK-hOCT1 or MDCK-hOCT2 cells using Lipofectamine 2000 Reagent. After a 14-day-cultivation with hygromycin B at the concentration of 400 µg · mL(-1), all clones were screened with DAPI and MPP+ as substrates to identify the best candidate. The mRNA content of hMATE1, the cellular accumulation of metformin with or without cimetidine as inhibitor, or transportation of cimetidine was further valuated. The results showed that all of the three cell models over expressed hMATE1 mRNA. The cellular accumulation of metformin in MDCK-hMATE1 was 17.6 folds of the control cell, which was significantly inhibited by 100 µmol · L(-1) cimetidine. The transcellular transport parameter net efflux ratios of cimetidine across MDCK-hOCT1/hMATE1 and MDCK-hOCT2/hMATE1 monolayer were 17.5 and 3.65, respectively. In conclusion, cell models with good hMATE1 function have been established successfully, which can be applied to study the drug transport or drug-drug interaction involving hMATE1 alone or together with hOCT1/2 in vitro.
Animals ; Biological Transport ; Cimetidine ; pharmacology ; DNA, Complementary ; Dogs ; Drug Interactions ; Humans ; Madin Darby Canine Kidney Cells ; Metformin ; pharmacology ; Organic Cation Transport Proteins ; genetics ; metabolism ; Transfection

AIMTo determine the effect of histamine on ischemia-induced cellular edema and viability reduction in rat hippocampal slices, and the involved subtypes of histamine receptor in this effect.

METHODSIn vitro ischemic injury of hippocampal slices was induced by oxygen-glucose deprivation (OGD). The slice injury was determined by real-timely measuring the changes of light transmittance (LT) for the cellular edema in CA1 region of the hippocampal slice, and by detecting the product of 2, 3, 5-triphenyltetrazolium chloride (TTC), formazan, for the slice viability. The effect of histamine at various concentrations on the slice injury was observed, and the blockage by antagonists of histamine receptors was also investigated.

RESULTSHistamine (0.01-10 micromol x L(-1)) inhibited the peak value of LT during OGD in hippocampal slices and improved the reduced viability after OGD. Diphenhydramine (0.1-10 micromol x L(-1)), an H1 receptor antagonist, did not affect the effect of histamine, while cimetidine (0.1-10 micromol x L(-1)), an H2 receptor antagonist, partly abolished the protective effect of histamine.

CONCLUSIONHistamine protects hippocampal slices against ischemia-induced cellular edema and viability reduction; this effect might be mediated via, at least partly, H2 receptor.

Animals ; Cell Hypoxia ; Cell Survival ; drug effects ; Cimetidine ; pharmacology ; Diphenhydramine ; pharmacology ; Formazans ; metabolism ; Glucose ; deficiency ; Hippocampus ; drug effects ; metabolism ; pathology ; Histamine ; pharmacology ; Histamine H1 Antagonists ; pharmacology ; Histamine H2 Antagonists ; pharmacology ; Male ; Neuroprotective Agents ; pharmacology ; Rats ; Rats, Sprague-Dawley

The present study was carried out to determine the role of histamine H(1) and H(2) receptors in the generation of basic respiratory rhythm. Neonatal (aged 0-3 d) Sprague-Dawley rats of either sex were used. The medulla oblongata slice containing the medial region of the nucleus retrofacialis (mNRF) and the hypoglossal nerve rootlets was prepared and the surgical procedure was performed in the modified Kreb's solution (MKS) with continuous carbogen (95% O(2) and 5% CO(2)), and ended in 3 min. Respiratory rhythmical discharge activity (RRDA) of the rootlets of hypoglossal nerve was recorded by suction electrode. Thirty medulla oblongata slice preparations were divided into 5 groups. In groups I, II and III, histamine (5 μmol/L), H(1) receptor specific antagonist pyrilamine (10 μmol/L) and H(2) receptor specific antagonist cimetidine (5 μmol/L) was added into the perfusion solution for 15 min separately. In group IV, after application of histamine for 15 min, additional pyrilamine was added into the perfusion for another 15 min. In group V, after application of histamine for 15 min, additional cimetidine was added into the perfusion for another 15 min. The discharges of the roots of hypoglossal nerve were recorded. Signals were amplified and band-pass filtered (100-3.3 kHz). Data were sampled (1-10 kHz) and stored in the computer via BL-420 biological signal processing system. Our results showed that histamine significantly decreased the respiratory cycle (RC) and expiratory time (TE), but changes of integral amplitude (IA) and inspiratory time (TI) were not statistically significant. Pyrilamine induced significant increases in RC and TE, but changes of TI and IA were not statistically significant. Cimetidine had no effects on RC, TE, TI and IA of RRDA. The effect of histamine on the respiratory rhythm was reversed by additional application of pyrilamine but not cimetidine. Taken together, with the results mentioned above, histamine H(1) receptors but not H(2) receptors may play an important role in the modulation of RRDA in the medulla oblongata slice preparation of neonatal rats.
Animals ; Animals, Newborn ; Cimetidine ; pharmacology ; Female ; Histamine ; pharmacology ; Histamine H1 Antagonists ; pharmacology ; Histamine H2 Antagonists ; pharmacology ; Hypoglossal Nerve ; physiology ; In Vitro Techniques ; Male ; Medulla Oblongata ; physiology ; Pyrilamine ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Histamine H1 ; physiology ; Receptors, Histamine H2 ; physiology ; Respiration

To determine the effect of stress on carotid sinus baroreceptor reflex (CSR) and whether or not central histaminergic receptors modulate the CSR under stress, the characteristics of CSR were analyzed by using an isolated carotid sinus preparation in Wistar rats. Animals were divided into two groups at random: unstressed group (n=42) and stressed group (n=41). According to the site of microinjection of histaminergic receptor antagonists, each group was subdivided into a group of intracerebroventricular injection (i.c.v.) and a group of microinjection into the nucleus of the solitary tract (NTS). The volume of injection into the lateral cerebroventricle and NTS was 5 microl and 1 micro1, respectively. Stressed groups were subjected to unavoidable electric foot-shock twice daily for a week, each session of foot-shock lasted 2 hours. The left and right carotid sinus regions were isolated from the systemic circulation under anesthesia with pentobarbital sodium in all rats. The intracarotid sinus pressure (ISP) was altered in a stepwise manner to trigger CSR from 0 to 280 mmHg at every step of 40 mmHg and 4 s, and then returned to 0 mmHg in similar steps. ISP and mean arterial pressure (MAP) were recorded simultaneously. ISP-MAP relationship curve was constructed by fitting to the logistic function with five parameters. The CSR parameters and the ISP-MAP relationship curve were separately compared statistically. The main results obtained are as follows. (1) Stress significantly shifted the ISP-MAP relationship curve upwards and obviously moved the middle part of ISP-Gain relationship curve downwards, and decreased the value of the MAP range and maximum gain (G(max)), but increased the threshold pressure (TP), saturation pressure (SP), set point and ISP at G(max) (ISP(Gmax)). (2) I.c.v. of H1 receptor antagonist chlorpheniramine (CHL, 5 microg) or H2 receptor antagonist cimetidine (CIM, 15 g) significantly diminished the above-mentioned changes in CSR performance induced by stress; the alleviative effect of CIM was less remarkable than that of CHL. The responses of CSR in stressed rats to H(1) or H(2) receptor antagonists generally occurred 20 min after the administration and lasted approximately for 15 min. (3) After microinjection of CHL (0.5 microg) or CIM (1.5 microg) into the NTS, the responses of CSR in stressed groups were similar to those after i.c.v. injection of CHL or CIM. (4) However, microinjection of CHL or CIM into the lateral cerebroventricle or the NTS could not completely abolish the stress-induced changes in CSR. These findings suggest that stress results in a resetting of CSR, a decrease in reflex sensitivity. The stress-induced changes in CSR may be mediated, at least in part, by activating the brain histaminergic system. The central histaminergic receptors (H(1) and H(2) receptors) may play an important role in the resetting of CSR under stress. The descending histaminergic pathway from the hypothalamus to NTS may be involved in these effects.
Animals ; Baroreflex ; drug effects ; physiology ; Brain ; metabolism ; physiology ; Carotid Sinus ; physiology ; Chlorpheniramine ; pharmacology ; Cimetidine ; pharmacology ; Histamine Antagonists ; pharmacology ; Male ; Random Allocation ; Rats ; Rats, Wistar ; Receptors, Histamine ; physiology ; Stress, Physiological ; physiology

The effects of anti-allergic drugs on intestinal mastocytosis and the expulsion of Neodiplostomum seoulense were observed in Sprague-Dawley rats, after oral infection with 500 metacercariae. The drugs used were hydroxyzine (a histamine receptor H1 blocker), cimetidine (a H2 blocker), cyclosporin-A (a helper T-cell suppressant), and prednisolone (a T- and B-cell suppressant). Infected, but untreated controls, and uninfected controls, were prepared. Worm recovery rate and intestinal mastocytosis were measured on weeks 1, 2, 3, 5, and 7 post-infection. Compared with the infected controls, worm expulsion was significantly (P < 0.05) delayed in hydroxyzine- and cimetidine-treated rats, despite mastocytosis being equally marked in the duodenum of all three groups. In the cyclosporin-A- and prednisolone-treated groups, mastocytosis was suppressed, but worm expulsion was only slightly delayed, without statistical significance. Our results suggest that binding of histamine to its receptors on intestinal smooth muscles is more important in terms of the expulsion of N. seoulense from rats than the levels of histamine alone, or mastocytosis.
Animals ; Cimetidine/pharmacology ; Cyclosporine/pharmacology ; Histamine H1 Antagonists/*pharmacology ; Histamine H2 Antagonists/*pharmacology ; Hydroxyzine/pharmacology/therapeutic use ; Immunosuppressive Agents/*pharmacology ; Intestinal Diseases, Parasitic/*drug therapy ; Mastocytosis/*drug therapy/parasitology ; Prednisolone/*pharmacology ; Rats ; Rats, Sprague-Dawley ; Support, Non-U.S. Gov't ; Trematoda/*growth & development/metabolism ; Trematode Infections/*drug therapy

Alcohol beverages have been used since the dawm of history and the pharmacology of alcohol has been studied extensively and the question whether alcohol is a stimulant has long been debated. now there seems little couble that alcohol is a primarys and continuous depressant of the CNS, and the general pharmacologic action of alcohol on the body is one of depression. The effects of various concentrations and type of alcoholic beverages on the gastrointestinal motor and secretory functions are influenced by a number of factors such as the state by the digestive processes, the presence or absence or gastrointestinal diseases, the amount and type of food present, the degree of tolerance for alcohol, accompanying psychological factiors, and so forth. it is generally accepted that gastirc secretion is stimulated by ehanol, but effects of ethanol on the motility of the gastrointestinal tract has not been clarified yet. Hence the present study was undertaken to investigate the effects of ethanol on gastrointestinal motility. The rabbits of either sex, weighting about 2kg, were killed by air embolism after 72 hours deprivation of food except water. The stomach and duodenum were isolated and cut into two parts, i.e. antrum and duodenum. Each strip of antrum and duodenum, sized 0.5X2.0cm, was placed in temperature controlled uscle chamber(37 degrees C) Containing Tyrode's solution and its contractile movement was recorded on Grass Polygraph(Model 7) via force displacement transducer(FT.03). The results are summarized as follows: 1) The strips of gastric antrum and duodenum showed spontaneous regular movement through the experimental period. Administration of ethanol from 0.1 to 1.0% inhibited the amplitude and frequency of both strips with dose-dependent manner. Most strips of the duodenum and 6 strips of the antrum showed relaxations of tone by ethanol and 4 strips of the antrum showed increased tone. 2) Tonic contraction of antral strips by ethanol was abolished only by the combined pretreatment of atropine and chlorpheniramine, or atropine and cimetidine, not by the phentolamine, proproanolol, atropine, hexamethonium, chlorpheniramine or cimetidine alone. 3) Inhibition of antral and duodenal motility by ethanol was not abolished by anyy one of the receptor blocking agents such as adrenergic alpha and beta, buscarinic, or histaminergic H-1 and H-2 receptor blocking agents. By the above resutls, it may be concluded that ethanol inhibits the motility of the duodenum, but excites or inhibits the motility of the gastric antrum. It is likely that the inhibitory effect of ethanol is it derect action on the smooth muscle, and the excitatory effect is mediated by a mechanism related with histamine and acetylcholine.
Acetylcholine ; Alcoholic Beverages ; Atropine ; Beverages ; Chlorpheniramine ; Cimetidine ; Depression ; Duodenum* ; Embolism, Air ; Ethanol* ; Gastrointestinal Diseases ; Gastrointestinal Motility ; Gastrointestinal Tract ; Hexamethonium ; Histamine ; Muscle, Smooth ; Pharmacology ; Phentolamine ; Poaceae ; Pyloric Antrum ; Rabbits ; Relaxation ; Stomach

OBJECTIVETo investigate histamine-induced changes of the intracortical vessels in the cortical slice of rat brain.

METHODSImmunohistochemistry was employed to detect the expression of H1 and H2 receptors in the intracortical blood vessels of rats. Histamine-induced constriction of the intracortical blood vessels of the brain slices was observed with differential interference contrast microscope. Measurements of the luminal diameter were made on-line during the course of the experiment and confirmed off-line from the stored images. In order to observe whether histamine H1 and H2 receptors affected histamine-induced constriction, the intracortical blood vessels in the brain slices were pre-treated with H1 receptor antagonist diphenhydramine and H2 receptor antagonist cimetidine.

RESULTSExpression of H1 and H2 receptors was detected in the intracortical blood vessels of the rat brain. Histamine (1-100 micromol/L) induced a concentration-dependent constriction from (1.48-/+0.67)% to (32.91-/+7.91)%. The reactions to each histamine concentration were significantly (P<0.01) different from each other, with the exception of the highest histamine concentrations (30 and 100 micromol/L) when maximal constriction due to histamine were observed (P>0.05). With pre-treatment of the slice with 10 micromol/L diphenhydramine, application of histamine did not elicit constriction. Pre-treatment of the slice with 10 micromol/L cimetidine did not completely inhibit but somehow significantly weakened vascular constriction in response to histamine treatment at 10 and 30 micromol/L (P<0.05).

CONCLUSIONHistamine can induce constriction of the intracortical blood vessels, which is mediated by H1 receptor.

Animals ; Blood Vessels ; drug effects ; metabolism ; physiology ; Cerebral Cortex ; blood supply ; Cimetidine ; pharmacology ; Diphenhydramine ; pharmacology ; Histamine ; pharmacology ; Histamine H1 Antagonists ; pharmacology ; Histamine H2 Antagonists ; pharmacology ; In Vitro Techniques ; Male ; Rats ; Rats, Sprague-Dawley ; Receptors, Histamine H1 ; metabolism ; physiology ; Receptors, Histamine H2 ; metabolism ; physiology ; Vasoconstriction ; drug effects

To study the enzyme kinetics of schizandrin metabolism in different gender in rat liver microsomes, liver microsomes were prepared from male or female rats. Schizandrin was incubated with rat liver microsomes. Schizandrin and its metabolites were isolated and identified by HPLC-UV method. Vmax, Km and Cl(int) of schizandrin in male and female rat liver microsomes were (21.88 +/- 2.30) and (0.61 +/- 0.07) micromol x L(-1) x min(-1) x mg(-1) (protein), (389.00 +/- 46.26) and (72.64 +/- 13.61) micromol x L(-1), (0.0563 +/- 0.0007) and (0.0084 +/- 0.0008) min x mg(-1) (protein), respectively. The major metabolites of schizandrin in female and male rat liver microsomes were 7,8-dihydroxy-schizandrin (M1) and 7, 8-dihydroxy-2-demethyl schizandrin (M2b), respectively. Ketoconazole, quinidine, and orphenadrine had different level effects on schizandrin metabolism in both male and female rat liver microsomes, and cimetidine still had some inhibitory effect in male liver microsomes. CYP3A and CYP2C11 may be the main P450 enzymes in schizandrin metabolism and their difference in rat liver microsomes may be the main reason for the sex difference of metabolic enzyme kinetics and metabolites of schizandrin in rats.
Animals ; Chromatography, High Pressure Liquid ; Cimetidine ; pharmacology ; Cyclooctanes ; isolation & purification ; metabolism ; Enzyme Inhibitors ; pharmacology ; Female ; In Vitro Techniques ; Ketoconazole ; pharmacology ; Lignans ; isolation & purification ; metabolism ; Male ; Microsomes, Liver ; metabolism ; Orphenadrine ; pharmacology ; Plants, Medicinal ; chemistry ; Polycyclic Compounds ; isolation & purification ; metabolism ; Rats ; Rats, Sprague-Dawley ; Schisandra ; chemistry ; Sex Factors ; Spectrophotometry, Ultraviolet

This paper is aimed to study the metabolic kinetics of nicousamide in rat liver microsomes and cytosol and to identify the major metabolite and drug metabolizing enzymes involved in the metabolism of nicousamide in rat and human liver microsomes by selective inhibitors in vitro. The concentration of nicousamide was determined by HPLC-UV method. The metabolite of nicousamide in rat and human liver microsomes was isolated and identified by LC-MS/MS. The major metabolite of nicousamide in rat and human liver microsomes was identified to be 3-(3'-carboxy-4'-hydroxy-anilino-carbo-)-6-amino-7-hydroxy-8-methyl-coumarin (M1). The metabolite of nicousamide in rat plasma, urine, bile and liver was consistent with M1. The metabolism of nicousamide can be catalyzed by several reductases, including CYP450 reductases, cytochrome b5 reductases and CYP2C6 in rat liver microsomes, as well as xanthine oxidase and DT-diaphorase in rat liver cytosol.
Adenosine Monophosphate ; pharmacology ; Allopurinol ; pharmacology ; Aniline Compounds ; metabolism ; Animals ; Cimetidine ; pharmacology ; Coumarins ; metabolism ; Cytochrome P-450 Enzyme Inhibitors ; Cytochrome P450 Family 2 ; Cytochrome-B(5) Reductase ; antagonists & inhibitors ; Cytosol ; metabolism ; Dicumarol ; pharmacology ; Enzyme Inhibitors ; pharmacology ; Female ; Humans ; Liver ; cytology ; metabolism ; Male ; Microsomes, Liver ; metabolism ; Mitochondria, Liver ; metabolism ; NAD(P)H Dehydrogenase (Quinone) ; antagonists & inhibitors ; Propylthiouracil ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Steroid 21-Hydroxylase ; antagonists & inhibitors ; Xanthine Oxidase ; antagonists & inhibitors