bluuebunny/crossref_metadata_2025 huggingface dataset:
Substance P‐induced inflammatory responses in guinea‐pig skin: The effect of specific NK1 receptor antagonists and the role of endogenous mediators
Authors: Walsh Desmond T. , Weg Vivian B. , Williams Timothy J. , Nourshargh Sussan
Published: July 2012

1 The sensory neuropeptide substance P (SP), when released from sensory nerves, has been implicated in the development of neurogenic inflammation. In the present study, using an in vivo model system, we have characterized and investigated the mechanisms underlying SP‐induced leukocyte accumulation and oedema formation in the guinea‐pig.

2 Intradermaly injected SP (i.d., 10−13‐10−9mol per site), induced a dose‐ and time‐dependent accumulation of 111In‐neutrophils, 111In‐eosinophils and oedema formation as measured by the local accumulation of i.v. injected l25I‐albumin. The leukocyte accumulation evoked by SP was significant at 10−10 and 10−9mol per site, whereas oedema formation was significant at the lowest dose tested (10−13mol per site).

3 The NK1 receptor antagonists, CP‐96,345 (1 mgkg−1, i.v.) and RP‐67,580 (10 μg per site, i.d.), significantly attenuated the oedema formation induced by the lower doses of SP. Oedema formation and leukocyte accumulation induced by 10−9mol per site SP were unaffected by either antagonist.

4 SP‐elicited responses were not significantly affected by the platelet activating factor (PAF) receptor antagonist, UK‐74,505 (2.5 mgkg−1, i.v.) or the H1 histamine receptor antagonist, chlorpheniramine (10−8mol per site, i.d.). However, the 111In‐eosinophil accumulation, but not the 111In‐neutrophil accumulation or oedema formation, induced by SP was significantly inhibited by the specific 5lipoxygenase (5‐LO) inhibitor, ZM‐230,487 (10−8 mol per site, i.d.).

5 The accumulation of both 111In‐neutrophils and 111In‐eosinophils induced by SP was abolished in guinea‐pigs treated i.v. with an anti‐CD 18 monoclonal antibody 6.5E F(ab′)2 (2.5 mgkg−1). The oedema response was unaffected in these animals.

6 These results suggest that SP‐induced inflammatory events may be mediated via two mechanisms involving NK1 receptor‐dependent and independent pathways. Oedema formation induced by the lower doses of SP may be mediated via the direct activation of NK1 receptors whilst, at higher doses, oedema formation and leukocyte accumulation may be mediated via the release of secondary mediators, possibly mast cell derived, with 5‐LO products playing an important role in the leukocyte infiltration. The leukocyte accumulation, but not the oedema induced by SP, is dependent on the expression of the CD 18 antigen on leukocytes.
Study of the in vivo and in vitro cardiovascular effects of (+)‐glaucine and N‐carbethoxysecoglaucine in rats
Authors: Orallo Francisco , Alzueta Alejandro Fdez , Campos‐Toimil Manuel , Calleja José Ma
Published: July 2012

1 The cardiovascular and vasorelaxant effects of (+)‐glaucine and of a semisynthetic derivative (N‐carbethoxysecoglaucine) were studied in rats.

2 N‐carbethoxysecoglaucine did not modify either systolic arterial pressure or heart rate values in conscious (25 mg kg−1, p.o.) and anaesthetized normotensive rats (5 mg kg−1, i.v.). Furthermore, this compound showed no activity in the experiments carried out on rat isolated aorta [contractility and 45Ca2+ influx assays (5 μm)] and did not modify the rate and force of contraction in rat isolated atria (5 μm).

3 In conscious normotensive rats, oral administration of (+)‐glaucine (25 mg kg−1) did not modify either systolic arterial pressure or heart rate.

4 In anaesthetized normotensive rats, (+)‐glaucine (5 mg kg−1, i.v.) produced a remarkable fall in mean arterial pressure (MAP) accompanied by a significant decrease in heart rate. In the same preparation, (+)‐glaucine (5 mg kg−1, i.v.) did not modify the cardiovascular effects induced by noradrenaline (NA) (5 μg kg−1) and 5‐hydroxytryptamine (5‐HT) (300 μg kg−1) but markedly inhibited those induced by nicotine (200 μg kg−1).

5 In isolated intact aorta of rat, (+)‐glaucine (0.15‐5 μm) competitively inhibited the contractions induced by NA (with a pA2 value of 7.14) and non‐competitively those induced by 5‐HT (in normal Krebs solution) and Ca2+ (in depolarizing Ca2+‐free high‐K+ 50 mM solution), with depression of the maximal response and with pD2′ values of 5.56 and 5.26, respectively.

6 In experiments in Ca2+‐free medium, (+)‐glaucine (3 μm) inhibited the contractions induced by NA and had no effect on either 5‐HT‐ or caffeine‐induced contractions.

7 Furthermore, in the experiments with radioactive Ca2+, (+)‐glaucine (3 μm) did not modify the basal uptake of 45Ca2+ but strongly inhibited the influx of 45Ca2+ induced by NA, 5‐HT and K+.

8 (+)‐Glaucine (5 μm) had no effect on rate and force of contraction in rat isolated atria.

9 These results indicate that: (a) the cardiovascular effects (hypotension and bradycardia) of (+)‐glaucine in anaesthetized normotensive rats (5 mg kg−1) may be due, at least in part, to a ganglioplexic effect; (b) the vasorelaxant action of (+)‐glaucine (0.15‐5 μm) in rat isolated aorta can be attributed to an α1adrenoceptor blocking property (which may explain its inhibition of noradrenaline‐induced 45Ca2+ influx and contractions in normal Krebs solution and noradrenaline‐induced contractions in Ca2+‐free medium) and to a Ca2+‐antagonist activity (which may be responsible, at least in part, for the inhibition of 45Ca2+ uptake induced by NA, 5‐HT and K+ and the contractions induced by both NA and 5‐HT in normal Krebs solution and by Ca2+ in Ca2+‐free high‐K+ medium) and (c) there is no correlation between the mechanisms of action observed for (+)‐glaucine in vivo and in vitro, which suggests that the vasorelaxant activity of this alkaloid does not contribute to its hypotensive activity.
Inhibitory effects of SR 58611A on canine colonic motility: evidence for a role of β3‐adrenoceptors
Authors: De Ponti Fabrizio , Cosentino Marco , Costa Angela , Girani Marco , Gibelli Graziano , D'Angelo Luigi , Frigo Gianmario , Crema Antonio
Published: July 2012

1 In order to clarify whether atypical or β‐adrenoceptors can modulate canine colonic motility in vivo, we studied the effects of SR 58611A (a selective agonist for atypical β‐adrenoceptors) alone and after pretreatment with β‐adrenoceptor antagonists on colonic motility in the conscious dog. The gastrocolonic response (postprandial increase in motility) was monitored by means of electrodes and strain‐gauge force transducers chronically implanted along the distal colon. In some experiments, heart rate was also measured. The possible role of β3‐adrenoceptors in mediating the effects of SR 58611A was also tested in vitro in circular muscle strips taken from the canine distal colon.

2 Intravenous infusion of SR 58611 A, ritodrine or isoprenaline at doses inducing the same degree of tachycardia inhibited the gastrocolonic response to a different extent, with SR 58611A and ritodrine being more effective than isoprenaline.

3 In a dose‐response study, SR 58611A was more potent in inhibiting colonic motility than in inducing tachycardia: the ED35 values for inhibition of colonic motility and induction of tachycardia were 23 and 156 μg kg−1, i.v., respectively.

4 The inhibitory effect of SR 58611A 100 μg kg−1, i.v., on the gastrocolonic response was reversed by alprenolol (non‐selective β‐adrenoceptor antagonist), but resistant to CGP 20712A (β1‐adrenoceptor antagonist) or ICI 118551 (β2‐adrenoceptor antagonist).

5 In vitro, SR 58611A concentration‐dependently relaxed circular muscle strips, an effect that was competitively antagonized by alprenolol with a pA2 value of 7.1, but resistant to CGP 20712A (100 nM), ICI 118551 (100 nM) or tetrodotoxin (1 μm).

6 The present study provides strong functional evidence for a role of atypical or β3‐adrenoceptors in the modulation of canine colonic motility both in vivo and in vitro by an inhibitory effect most likely at the smooth muscle level.
Effect of inhibition of nitric oxide synthesis on the uptake of LDL and fibrinogen by arterial walls and other organs of the rat
Authors: Cardona‐Sanclemente L.E. , Born G.V.R.
Published: July 2012

1 The effects of administering 3 mg ml−1 NG‐nitro‐L‐arginine methyl ester (L‐NAME), an inhibitor of nitric oxide (NO), on the uptake of low density lipoprotein (LDL), fibrinogen and blood pressure were determined in conscious, unrestrained, cannulated normotensive and spontaneously hypertensive (SHR) Wistar rats.

2 The uptake of LDL and fibrinogen, labelled respectively with 125I or 131I via the adduct tyramine cellobiose ([125I]TC‐LDL and [131I]TC‐fibrinogen), were compared in aortic walls, heart, skeletal muscle, lung, liver, kidney and adrenal during the final 24 h of 6 days' administration of L‐NAME in the drinking water.

3 In control normotensive rats, the systolic blood pressure did not change significantly over 6 days, while administration of L‐NAME in normotensive rats increased the blood pressure progressively and significantly to about 170 mmHg over the same period.

4 In normotensive rats L‐NAME increased significantly the uptake of both LDL and fibrinogen by aortic walls and heart, but not by muscle, lung, liver, kidney and adrenal.

5 The blood pressure in SHR was about 170 mmHg before administration of L‐NAME and did not increase significantly after 6 days of treatment. In these rats the uptake of LDL or of fibrinogen was increased only in the heart but not in aortic walls nor in any of the other organs.

6 In normotensive rats the increase in blood pressure caused by inhibition of NO generation was associated with increases in the uptake of the atherogenic plasma proteins LDL and fibrinogen by the wall of the aorta and by the heart but not by the skeletal muscle, lung, liver, kidney and adrenal. The slightly higher blood pressure of SHR treated with L‐NAME was not associated with increased uptake of LDL or fibrinogen by aorta nor by any organ except heart. Thus, while in normotensive rats the increase in blood pressure caused by inhibition of NO generation was associated with increase in the uptake of atherogenic plasma proteins LDL and fibrinogen by the wall of the aorta and by the heart, in SHR which showed uptakes similar to the normotensive animals, the non‐significant increase in blood pressure induced by inhibition of NO generation was not associated with increased uptake of LDL or fibrinogen in any organ except the heart.

7 These results are consistent with effects, demonstrated earlier, of infusing the pressor agents noradrenaline, adrenaline and angiotensin II, which produce increases in uptake of LDL and fibrinogen by aortic wall, whereas this is not so in spontaneously hypertensive rats.
Potentiation by aminopeptidase P of blood pressure response to bradykinin
Authors: Kitamura Shin‐Ichi , Carbini Luis A. , Carretero Oscar A. , Simmons William H. , Scicli A. Guillermo
Published: July 2012

We examined whether a specific aminopeptidase P (APP) inhibitor, apstatin, increases vasodepressor responses to bradykinin in anaesthetized rats, and whether it would augment blood pressure responses further after treatment with the angiotensin‐converting enzyme inhibitor (ACEi), lisinopril. Apstatin doubled the maximum blood pressure response to bradykinin. The area under the curve (AUC), which incorporates both peak blood pressure changes and duration of response, was doubled in apstatin‐treated rats vs controls and in the apstatin + lisinopril group vs lisinopril alone. These data demonstrate that APP is an important kininase in vivo.
Electrophysiological effects of Ro 22–9194, a new antiarrhythmic agent, on guinea‐pig ventricular cells
Authors: Maruyama Kazuyasu , Kodama Itsuo , Anno Takafumi , Suzuki Ryouko , Toyama Junji
Published: July 2012

Cardiac effects of Ro 22–9194 were examined in papillary muscles and single ventricular myocytes isolated from guinea‐pigs and compared with those of moricizine.

In papillary muscles, both Ro 22–9194 (≥ μm) and moricizine (≥ μm) caused a significant dose‐dependent decrease in the maximum upstroke velocity (V̇max) and a shortening of the action potential duration.

In the presence of either drug, trains of stimuli at rates ≥ 0.2 Hz led to an exponential decline in V̇max. This use‐dependent block was enhanced at higher stimulation frequencies. A time constant (τR) for V̇max recovery from the use‐dependent block was 9.3 s for Ro 22–9194 and 26.4 s for moricizine.

The curves relating membrane potential and V̇max in single myocytes were shifted by Ro 22–9194 (30 μm) or by moricizine (3 μm) in a hyperpolarizing direction by 8.4 mV and 8.0 mV respectively.

In myocytes treated with Ro 22–9194 (30 μm), a 10 ms conditioning clamp to 0 mV caused a significant decrease in V̇max of the subsequent test action potential; further prolongation of the clamp pulse duration resulted in a modest enhancement of the V̇max inhibition. In the presence of moricizine (3 μm), a similar conditioning clamp > 200 ms caused a significant V̇max reduction; the longer the clamp pulse duration, the greater the V̇max reduction.

Ro 22–9194 ≥ 30 μm caused a slight decrease of calcium inward current (ICa) of myocytes without affecting the delayed rectifier potassium current (IK).

These findings suggest that the primary electrophysiological effect of Ro 22–9194 as an antiarrhythmic agent is, like moricizine, a use‐ and voltage‐dependent inhibition of sodium channels. From the onset and offset kinetics of the use‐dependent block, Ro 22–9194 belongs to the intermediate kinetic Class I drugs, while moricizine is a slow kinetic drug. From the state‐dependence of sodium channel block, Ro 22–9194 may belong to activated channel blockers, while moricizine belongs to inactivated channel blockers.
Production of antinociception by peripheral administration of [Lys7]dermorphin, a naturally occurring peptide with high affinity for μ‐opioid receptors
Authors: Negri Lucia , Lattanzi Roberta , Melchiorri Pietro
Published: July 2012

The opioid activity of the amphibian peptide, [Lys7]dermorphin, was studied in rats and mice. When administered intracerebroventricularly (i.c.v.), intravenously (i.v.) or subcutaneously (s.c.) it produced a long lasting analgesia. Its antinociceptive potency exceeded that of morphine 290 times by i.c.v. injection, and 25–30 times by peripheral administration.

The dose‐response curves of [Lys7]dermorphin antinociception were shifted to the right by the pretreatment with naloxone (0.1 mg kg−1, s.c.) or with the μ1‐selective antagonist, naloxonazine (10 mg kg−1, i.v. 24 h before peptide injection).

The peptide also displayed potent antinociceptive effects in a chronic inflammatory pain model (rat Freund's adjuvant arthritis). In this pain model, systemic administration of the peptide raised the nociceptive threshold more in inflamed than in healthy paw.

High central and peripheral doses of [Lys7]dermorphin in rats produced catalepsy. The cataleptic response was antagonized by naloxone but left unchanged by naloxonazine pretreatment.

In rats and mice, central or peripheral administration of [Lys7]dermorphin induced a significantly slower development of tolerance to the antinociceptive effect than did morphine.

Upon naloxone precipitation of the withdrawal syndrome, [Lys7]dermorphin‐dependent mice made fewer jumps and lost less weight than the morphine‐dependent animals. Withdrawal hyperalgesia did not develop in [Lys7]dermorphin‐dependent mice.

In conclusion, [Lys7]dermorphin seems to be a unique opioid peptide having a high penetration into the blood‐brain barrier despite its low lipid solubility. This peptide causes fewer side‐effects than other opioids and appears less likely than morphine to cause physical dependence in rats and mice.
The receptor occupation and plasma concentration of NKY‐722, a water‐soluble dihydropyridine‐type calcium antagonist, in spontaneously hypertensive rats
Authors: Uchida S. , Yamada S. , Ohkura T. , Heshikiri M. , Yoshimi A. , Shirahase H. , Kimura R.
Published: July 2012

The occupation in vivo by NKY‐722 of 1,4‐dihydropyridine (DHP) calcium antagonist receptors in myocardium, aorta and cerebral cortex was investigated. At 1 and 3 h after oral administration of NKY‐722 (3 mg kg−1) in spontaneously hypertensive rats (SHR), there was a significant (44 and 41%, respectively) decrease in the number of myocardial (+)‐[3H]‐PN 200‐110 binding sites (Bmax) compared to control values. A greater reduction of Bmax values was observed at 1 (86%), 3 (88%), 6 (63%) and 12 (46%) h later by a higher dose (10 mg kg−1) of this drug. The occupation of myocardial 1,4‐DHP calcium antagonist receptors after oral administration of NKY‐722 correlated significantly with its plasma concentration. There was a significant decrease in cerebral cortical (+)‐[3H]‐PN 200‐110 binding (Bmax) at 1 and 3 h after oral administration of NKY‐722 (10 mg kg−1).

Oral administration of nicardipine (10 mg kg−1) in SHR caused a significant reduction of Bmax values for (+)‐[3H]‐PN 200‐110 binding in myocardium at 1 and 3 h later and in cerebral cortex at 1 h later.

The in vivo specific binding of (+)‐[3H]‐PN 200‐110 in particulate fractions of aorta of SHR was significantly (79 and 83%, respectively) reduced at 1 and 6 h after oral administration of NKY‐722 (3 mg kg−1), while myocardial (+)‐[3H]‐PN 200‐110 binding was decreased by 52% only at 1 h later. Also, nicardipine administration reduced in vivo (+)‐[3H]‐PN 200‐110 binding in aorta at 1 and 6 h later and in myocardium at 1 h later. On the other hand, the administration of both NKY‐722 and nicardipine had no significant effect on in vivo (+)‐[3H]‐PN 200‐110 binding in cerebreal cortex.

It is concluded that NKY‐722 may exert more selective and sustained occupation in vivo of 1,4‐DHP calcium antagonist receptors in vascular tissues of SHR than in myocardial and brain tissues.
The effect of chlormethiazole on neuronal damage in a model of transient focal ischaemia
Authors: Sydserff S.G. , Cross A.J. , West K.J. , Green A.R.
Published: July 2012

The effect of chlormethiazole has been studied in a transient middle cerebral artery (MCA) occlusion model of cerebral ischaemia in the rat. The MCA was occluded for 1 h by use of an intraluminal suture technique, with reperfusion for 24 h following removal of the occluding filament. Neuronal damage was determined by measurement of the area of necrosis following Cresyl Violet staining of sections taken through the ischaemic region.

In the initial experiment, occlusion of the MCA produced a large volume of ischaemic damage in both cortex and striatum, characterized by necrosis and pyknosis (total volume of damage, 287 ± 13 mm3; n = 9). Rats injected with chlormethiazole (1000 μmol kg−1, i.p.) 60 min before occlusion had a reduced volume of damage in both regions (104 ± 11 mm3; n = 9; P < 0.001).

In a subsequent study systemic physiological parameters (heart rate, blood pressure, blood pH, blood gases and rectal temperature) were measured throughout the ischaemic period.

Chlormethiazole (10000 μmol kg−1) pretreatment produced little change in systemic physiology and the neuroprotective effect of the drug when given 60 min prior to the MCA occlusion was confirmed. Chlormethiazole was also neuroprotective when given 10 min following the start of reperfusion (control group: 244 ± 52 mm3, n = 10; chlormethiazole pretreatment group: 102 ± 23 mm3, n − 10; P < 0.001; chlormethiazole post‐ischaemia group: 122 ± 16mm3; P<0.001, n= 10).

It is concluded that chlormethiazole is an effective neuroprotective agent in this model of transient focal ischaemia. The observation that chlormethiazole is protective when given after reperfusion indicates that the effect of the drug is unlikely to be due to an alteration of intra‐ischaemic cerebral blood flow, but is more probably a direct effect on the development of ischaemic damage.
Enhancement by 5‐hydroxytryptamine and analogues of desensitization of neuronal and muscle nicotinic receptors expressed in Xenopus oocytes
Authors: Cross K.M.L. , Foreman R.C. , Chad J.E.
Published: July 2012

The action of 5‐hydroxytryptamine (5‐HT) on neuronal and muscle nicotinic acetylcholine receptors (nicotinic AChR) expressed in Xenopus oocytes was studied.

5‐HT enhanced the rate of desensitization of the acetylcholine (ACh) current response in all receptor subtypes investigated (muscle, αβ2γδ and α4β2), acting in a dose‐dependent manner.

5‐HT also reduced the peak current elicited by ACh in a dose‐dependent manner. The IC50 value for the muscle type receptor was 227 ± 0.44 μm, and 166 ± 0.47 μm and 283 ± 0.28 μm for the combinations αβ2γ and α4β2 respectively.

The effect of 5‐HT on the responses to ACh (10 μm) was found to be independent of membrane voltage over the range tested (−80 to −10 mV), and to be readily reversed by washout.

The action of 5‐HT could be mimicked by structurally similar molecules. The homologue tryptamine was less potent than 5‐HT in blocking the ACh current, with an IC50 of 1.0 ± 0.02 mM. Ketanserin, a 5‐HT2 receptor antagonist, was more potent than 5‐HT, the IC50 being 49.0 ± 1.4 μm.

We postulate that a highly conserved portion of the tertiary structure of nicotinic AChRs, which includes some part of the ACh binding site, has affinity for 5‐HT and structural analogues.
Effect of UK‐84149 on voltage‐activated calcium currents of single smooth muscle cells from guinea‐pig and rabbit jejunum and rabbit coronary artery
Authors: Zhang H. , Bolton T.B.
Published: July 2012

Smooth muscle cells of the longitudinal muscle of the guinea‐pig and the rabbit jejunum and rabbit coronary artery were dispersed by enzyme treatment and recordings of membrane current were made in the standard whole cell voltage‐clamp mode and by perforated patch technique. The effect of UK‐84149 on the voltage‐dependent calcium inward current of single isolated smooth muscle was studied at room temperature.

When inward and outward currents were evoked by stepping to O mV or + 10 mV from − 80 mV every 20 s, UK‐84149 reduced the voltage‐dependent inward current in guinea‐pig jejunum smooth muscle cells with a ID50 of 2.3 μm, and also reduced voltage‐dependent outward current with a ID50 of 7.2 μm. The effect of UK‐84149 was difficult to wash out.

The inactivation of the inward current was studied by holding at various potentials for 10 s before evoking inward current at a test potential of 0 mV. The voltage‐inactivation curve was shifted to the left by 3 μm UK‐84149. The voltage at which current was 50% available (Vh) was changed from − 37 ± 2 mV to − 50 mV ± 2.2 (n = 6, means ± s.e.mean).

When inward current was evoked by stepping to 0 mV from − 80 mV for 50 ms, every 20 s, nicardipine immediately, and verapamil and UK‐84149 slowly, reduced the peak amplitude. Inhibition by the latter two drugs depended on the number of stimulations applied. So, like verapamil, UK‐84149 had a use‐dependent action.

The effect of UK‐84149 on inward current from rabbit jejunum and coronary artery smooth muscle cells was compared with the effect of nicardipine and D600. When inward current was evoked by stepping to 0 mV from − 80 mV every 20 s, UK‐84149 inhibited inward currents from both types of smooth cell with an ID50 of 1.7 μm for jejunum and an ID50 of 3.2 μm for coronary artery. ID50 values of D600 were 8.1μm for jejunum and 3.9 μm for coronary artery. ID50 values of nicardipine were 24 nM for jejunum and 12 nM for coronary artery.

The results of the present studies indicate that UK‐84149 has a calcium‐antagonist action that can explain its inhibitory action on bowel motility. Its bowel selectivity may arise due to its use‐dependent, and persistent, action.
NPC 15669‐modulated human polymorphonuclear neutrophil functional responsiveness: effects on receptor‐coupled signal transduction
Authors: Smith Robert J. , Justen James M. , Bleasdale John E. , Sly Laurel M.
Published: July 2012

The effect of NPC 15669, N‐carboxy‐L‐leucine, N‐[(2,7‐dimethylfluoren‐9‐yl)methyl]ester), an inhibitor of human polymorphonuclear neutrophil (PMN) adhesion, on granule exocytosis and the oxidative burst was investigated in PMN activated with receptor‐specific pathophysiological stimuli.

NPC 15669 caused a concentration‐dependent (1–30 μm) inhibition of the extracellular release of azurophil (myeloperoxidase) and specific (vitamin B12‐binding protein) granule constitutents from PMN exposed to N‐formyl‐methionyl‐leucyl‐phenylalanine (FMLP), leukotriene B4 (LTB4), platelet activating factor (PAF), C5a and interleukin‐8 (IL‐8).

The receptor agonist‐triggered PMN oxidative burst, measured as superoxide anion (O‐2) production, was suppressed by NPC 15669.

Phorbol myristate acetate (PMA)‐stimulated degranulation and O‐2) production were unaffected by NPC 15669.

NPC 15669 (0.1–10 μm) inhibited receptor‐triggered inositol 1,4,5‐trisphosphate (IP3) production and the IP3‐triggered increase in cytosolic‐free calcium ([Ca2+] I) in FMLP‐activated PMN, but not in cells exposed to the other receptor agonists.

NPC 15669 suppressed FMLP but not PMA‐stimulated redistribution of protein kinase C (PKC) in PMN.

The specific binding of [3H]‐FMLP but not [125I]‐C5a to PMN was inhibited by NPC 15669.

NPC 15669 suppressed O‐2 production and the rise in [Ca2+]i in PMN treated with the guanine nucleotide‐binding protein (G‐protein) activators, sodium fluoride (NaF) and mastoparan, respectively.

The results show that NPC 15669 inhibits PMN responsiveness to various receptor agonists, and suggest interference with receptor‐coupled signal transduction in this inflammatory cell at both the receptor and post‐receptor level in a stimulus‐specific manner.
Mechanism of action of the inhibitory effect of nifedipine on the growth of cultured aortic cells from spontaneously hypertensive and normotensive rats
Authors: Hérembert Thierry , Zhu Ding‐Liang , Marche Pierre
Published: July 2012

To gain insight into the parameters which control vascular structure, we investigated the mechanisms whereby nifedipine, and other dihydropyridines, inhibit the growth of cultured fibroblasts isolated from the adventitia of the aorta of spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats.

The effects of nifedipine on cell proliferation and on serum‐induced DNA synthesis were determined by measuring the cell number and the incorporation of [3H]‐thymidine, respectively. The mechanism of action of nifedipine was studied by adding the drug either to randomly growing cells or to quiescent, G0/G1 arrested and synchronized cells. The effects of varying the duration of drug treatment were also examined.

In randomly growing cultures nifedipine, like other dihydropyridines concentration‐dependently inhibited cell proliferation; the rank order of effect (measured at a concentration of 10 μm) was nifedipine> nisoldipine> nitrendipine∼ nimodipine.

In G0/G1 arrested cell cultures, nifedipine concentration‐dependently inhibited serum‐induced [3H]‐thymidine incorporation. In this respect it had similar effects in cell cultures from WKY and SHR. In both SHR and WKY cultures, nifedipine delayed the transition from G0/G1 to S phase, and inhibited serum‐induced DNA synthesis possibly by acting on the early G1 phase.

In cell cultures from both SHR and WKY, serum‐induced DNA synthesis was similarly (∼40%) inhibited after a 1 day treatment with 10 μm nifedipine. In contrast, after 5 days treatment with the drug, the inhibition of DNA synthesis was ∼65% and ∼10% in SHR and WKY cultures, respectively. The inhibitory effects of nifedipine against proliferation of fibroblasts were ∼25% and 60%, respectively, after 1 and 5 days of treatment, and were similar in cells derived from SHR and WKY. This indicates that 5 days treatment with nifedipine inhibited the proliferation of SHR and WKY fibroblasts by acting mostly on the early G1 phase and the m phase, respectively.

Irrespective of the duration of treatment (1 or 5 days) with 10 μm nifedipine, the inhibition of DNA synthesis could be abolished and partially reduced by Bay K 8644 (1 μm) in WKY and SHR fibroblasts, respectively. In cell cultures from both SHR and WKY the inhibitory effects of a short term and of a long term treatment with nifedipine against cell proliferation were reduced and unaffected, respectively by Bay K 8644.

These results indicate that nifedipine inhibited cell proliferation and serum‐induced DNA synthesis by altering the cell cycle through different mechanisms in SHR and WKY fibroblasts. They also suggest the existence in aortic fibroblasts of interactions between calcium channel blockers of the dihydropyridine series and the mitogenic signalling pathways of growth factors contained in serum.
Effects of 8‐bromo cyclic GMP and verapamil on depolarization‐evoked Ca2+ signal and contraction in rat aorta
Authors: Salomone Salvatore , Morel Nicole , Godfraind Théophile
Published: July 2012

The pharmacological action of NO donors is usually attributed to a cellular rise in guanosine 3′:5′‐cyclic monophosphate (cyclic GMP), but this hypothesis is based only on indirect evidence. Therefore, we have studied the effects of cyclic BMP on Ca2+ movements and contraction in rat isolated endothelium‐denuded aorta stimulated by KC1 depolarizing solution using the permeant analogue 8‐bromo cyclic BMP (BrcGMP). Isometric contraction and fura‐2 Ca2+ signals were measured simultaneously in preparations treated with BrcGMP and with verapamil. The activation of calcium channels was estimated by measuring the quenching rate of the intracellular fura‐2 signal by Mn2+ and by the depolarization‐dependent influx of 45Ca2+.

Stimulation with 67 mM KCl‐solution evoked an increase in cytosolic Ca2+ concentration ([Ca2+]cyt) and a contractile response which were inhibited by pretreatment with verapamil (0.1 μm) or BrcGMP (0.1‐1 mM). However, the inhibition of the fura‐2 Ca2+ signal was significantly higher with verapamil than with BrcGMP, whereas the contraction was inhibited to a similar extent.

When preparations were exposed to K+‐depolarizing solution in which the calcium concentration was cumulatively increased, the related increase in fura‐2 Ca2+ signal was barely affected by BrcGMP, whereas the contractile tension was strongly and significantly inhibited.

Cellular Ca2+ changes were also estimated with 45Ca2+. 45Ca2+ influx in resting preparations was significantly reduced by BrcGMP (0.1 mM) but not by verapamil (0.1 μm); 45Ca2+ influx in KC1‐depolarized preparations was reduced by verapamil but was unaffected by BrcGMP.

Measurements of Mn2+‐induced quenching of the intracellular fura‐2 signal showed that BrcGMP did not affect divalent cation entry in K+‐stimulated preparations, whereas verapamil concentration‐dependently inhibited Mn2+ entry stimulated by K+‐depolarization.

The present results indicate that BrcGMP did not affect voltage‐dependent Ca2+ channel gating in the rat aorta. For a given fura‐2 Ca2+ signal, the contraction was lower in preparations exposed to BrcGMP than in the untreated ones, suggesting that the activation of cyclic GMP‐dependent kinases reduced the contractile efficacy of calcium. Furthermore, the reduction of depolarization‐dependent 45Ca2+ uptake reported with sodium nitroprusside, a NO donor, was not observed with biologically active concentrations of BrcGMP, suggesting that this drug could have additional mechanisms of action, unrelated to activation of protein G‐kinase.
Prevention by blockade of angiotensin subtype1‐receptors of the development of genetic hypertension but not its heritability
Authors: Madeddu Paolo , Anania Vittorio , Varoni Maria Vittoria , Parpaglia Paolo Pinna , Demontis Maria Piera , Fattaccio Maria Caterina , Palomba Domenico , Pollock David , Glorioso Nicola
Published: July 2012

We determined whether early inhibition of angiotensin II subtype1 (AT1) receptors by the newly synthesized nonpeptidic antagonist, A‐81988, can attenuate the development of hypertension in spontaneously hypertensive rats (SHR) and if the altered blood pressure phenotype can be passed on to the subsequent generation, not exposed to the antagonist.

Pairs of SHR were mated while drinking tap water or A‐81988 in tap water, and the progeny was maintained on the parental regimen until 14 weeks of age. At this stage, A‐81988‐treated rats showed lower systolic blood pressure and body weight values (136 ±5 versus 185 ±4 mmHg and 247 ±4 versus 283±4 g in controls, P<0.01), while heart rate was similar. In addition, mean blood pressure was reduced (101 ±7 versus 170 ±7 mmHg in controls, P < 0.01), and the pressor responses to intravenous or intracerebroventricular angiotensin II were inhibited by 27 and 59%, respectively. Heart/body weight ratio was smaller in A‐81988‐treated rats (3.2±0.1 versus 3.8±0.1 in controls, P<0.01).

The antihypertensive and antihypertrophic effect of A‐81988 persisted in rats removed from therapy for 7 weeks (systolic blood pressure: 173 ±4 versus 220 ±4 mmHg, heart/body weight ratio: 3.4 ±0.1 versus 4.1 ±0.1 in controls at 21 weeks of age, P < 0.01 for both comparisons), whereas the cardiovascular hypertensive phenotype was fully expressed in the subsequent generation that was maintained without treatment.

These results indicate that chronic blockade of angiotensin AT1‐receptors attenuates the development of hypertension in SHR but it does not prevent the transmission of hypertension to the following generation. Thus, heritability of the SHR's hypertensive trait is not affected by pharmacological manipulation of the cardiovascular phenotype.
Reduction of inflammation and pyrexia in the rat by oral administration of SDZ 224‐015, an inhibitor of the interleukin‐1β converting enzyme
Authors: Elford P.R. , Heng R. , Révész L. , MacKenzie A.R.
Published: July 2012

The aim of this study was to determine whether a synthetic inhibitor of the interleukin‐1β converting enzyme (ICE) displays oral activity in models of inflammation.

To this end, the ICE inhibitor, SDZ 224‐015, was examined in rat paw oedema, pyrexia and nociception tests.

SDZ 224‐015 (0.3–300 μg kg−1) potently reduced carrageenin‐induced paw oedema, with an oral ED50 of approximately 25 μg kg−1. This effect was independent of endogenous glucocorticoid, as shown by retention of activity upon adrenalectomy.

Pyrexia induced by lipopolysaccharide (0.1 mg kg−1 s.c.) or by interleukin‐1β (100 ng i.v.) was also reduced, over a similar dose‐range to oedema (oral ED50S 11 μg kg−1 and 4 μg kg−1 respectively).

SDZ 224‐015 (0.2–5 mg kg−1, p.o.) displayed analgesic activity in the Randall‐Selitto yeast‐inflamed paw pressure test, significant at a dose of 1 mg kg−1, p.o. 6 Thus, SDZ 224‐015 has potent oral activity in several acute models for inflammation, suggesting that ICE inhibitors may constitute a novel type of anti‐inflammatory agent.
Regional haemodynamic effects of μ‐, δ‐, and κ‐opioid agonists microinjected into the hypothalamic paraventricular nuclei of conscious, unrestrained rats
Authors: Bachelard Hélène , Pître Maryse
Published: July 2012

The cardiovascular effects of bilateral injection into the hypothalamic paraventricular nuclei of selective μ‐, δ‐, and κ‐opioid receptor agonists were investigated in conscious, unrestrained Wistar Kyoto rats, chronically instrumented with pulsed Doppler flow probes for measurement of regional haemodynamics.

The selective μ‐agonist [D‐Ala2, MePhe4, Gly5ol]enkephalin (DAMGO), injected bilaterally into the hypothalamic paraventricular nuclei (0.01‐1.0 nmol), caused increases in blood pressure, tachycardias, vasoconstriction in renal and superior mesenteric vascular beds and substantial vasodilatation in the hindquarter vascular bed.

The administration of increasing doses (0.01–5.0 nmol) of the selective δ‐agonist [D‐Phe2,5]enkephalin (DPDPE) or the selective κ‐agonist, U50488H into the paraventricular nuclei (PVN) had no significant effect on blood pressure, heart rate, or regional haemodynamics.

Together, the present results are further evidence of a role for opioid peptides, especially acting at μ‐receptors in the PVN, in the central regulation of the cardiovascular system, whereas a role for opioid peptides, acting at δ‐ and κ‐receptors in the PVN, seems less obvious from the present results.
Characterization of the receptors and mechanisms involved in the cardiovascular actions of sCCK‐8 in the pithed rat
Authors: Gaw Alasdair J. , Hills David M. , Spraggs Colin F.
Published: July 2012

The cardiovascular actions of cholecystokinin and related peptides were investigated in the pithed rat. The receptors and the mechanisms involved in these experiments were characterized.

Sulphated cholecystokinin octapeptide (sCCK‐8, 0.1–100 nmol kg−1, i.v.) elicited a dose‐dependent bradycardia and increase in mean arterial blood pressure. Neither gastrin‐17 nor pentagastrin had any effect at concentrations up to 100 nmol kg−1.

Both the pressor response and bradycardia elicited by sCCK‐8 were reduced by the selective CCKA receptor antagonists, devazepide (0.5–50 nmol kg−1) and lorglumide (1–7 μmol kg−1). The selective CCKB receptor antagonists, CI‐988 (1 μmol kg−1) and L‐365,260 (15 μmol kg−1) did not inhibit the effects of sCCK‐8.

The pressor response induced with sCCK‐8 was reduced by treatment with either phentolamine (3 μmol kg−1) or guanethidine (2 μmol kg−1) and was unaffected by treatment with propranolol, atropine or hexamethonium. The pressor response also persisted following bilateral adrenalectomy.

The bradycardia induced with sCCK‐8 was unaffected by treatment with phentolamine, propranolol, guanethidine, atropine, hexamethonium or bilateral adrenalectomy.

The tetrapeptide of cholecystokinin (CCK‐4) elicited a dose‐dependent pressor response but did not induce bradycardia. The pressor response was unaffected by devazepide (50 nmol kg−1), L‐365260 (15 μmol kg−1) or phentolamine (3 μmol kg−1).

In the pithed rat, sCCK‐8 acted via CCKA receptors to increase arterial blood pressure indirectly, at least in part, through activation of α‐adrenoceptors. The observed bradycardia was also mediated by CCKA receptors but possibly through a direct action on the heart.
Comparison of the interaction of agmatine and crude methanolic extracts of bovine lung and brain with α2‐adrenoceptor binding sites
Authors: Pinthong D. , Hussain J.F. , Kendall D.A. , Wilson V.G.
Published: July 2012

In the present study we have evaluated whether α2‐adrenoceptor binding sites on bovine cerebral cortex membranes labelled by [3H]‐clonidine, [3H]‐idazoxan and [3H]‐RX‐821002 can distinguish between known agonists and antagonists. This model has then been used to compare the binding profiles of the putative non‐catecholamine, clonidine‐displacing substance (CDS), agmatine and crude methanolic extracts of bovine lung and brain.

Saturation studies carried out in the presence and absence of noradrenaline, 10 μmol l−1, revealed that the maximum number of binding sites on bovine cerebral cortex membranes for [3H]‐idazoxan and [3H]‐RX‐821002 were approximately 60–80% greater than those for [3H]‐clonidine (62.6 fmol mg−1 protein). Rauwolscine, the selective α2‐adrenoceptor antagonist, was approximately 100 fold more potent against each of the ligands than the selective α1adrenoceptor diastereoisomer, corynanthine. Also, the pKi value for the selective α1‐adrenoceptor prazosin against each ligand was less than 6.

Adrenaline, UK‐14034, rauwolscine, corynanthine, RX‐811059 and prazosin produced concentration‐dependent inhibition of binding of all three 3H‐ligands. The agonists, adrenaline and UK‐14304, were approximately 5 and 10 fold less potent against [3H]‐idazoxan and [3H]‐RX‐821002, respectively, than against [3H]‐clonidine. In marked contrast, the antagonists, rauwolscine, corynanthine, RX‐811059 and prazosin exhibited a different profile, being approximately 2–3 fold more potent against sites labelled by [3H]‐RX‐821002 and [3H]‐idazoxan compared to sites labelled by [3H]‐clonidine.

Agmatine and histamine produced a concentration‐dependent displacement of [3H]‐clonidine, [3H]‐idazoxan and [3H]‐RX‐821002 binding to bovine cerebral cortex membranes. The pKi values for agmatine and histamine were independent of the 3H‐ligand employed, approximately 4.8 and 4.5, respectively.

Crude methanolic extracts of bovine brain and lung produced a concentration‐dependent inhibition of [3H]‐clonidine binding to bovine cerebral cortex membranes (>90%). Based on the volume of the extract that caused 50% inhibition of [3H]‐clonidine binding, bovine lung contains 3 fold more CDS than bovine brain. Both extracts were at least 5 fold more potent against α2‐adrenoceptor sites labelled by [3H]‐clonidine than those labelled by [3H]‐idazoxan and [3H]‐RX‐821002.

All three 3H‐ligands label the same population of α2‐adrenoceptor binding sites on bovine cerebral cortex membranes, but [3H]‐clonidine appears to label selectively the ‘agonist’ state of the sites: for which known agonists, adrenaline and UK‐14304, exhibit a higher affinity. Our results indicate that neither agmatine nor histamine can account for the CDS activity present in crude extracts of bovine brain and lung. Moreover, these extracts appear to possess a binding profile similar to that of adrenaline and UK‐14304, suggesting that they may possess agonist activity.
Effect of frusemide, ethacrynic acid and indanyloxyacetic acid on spontaneous Ca‐activated currents in rabbit portal vein smooth muscle cells
Authors: Greenwood I.A. , Hogg R.C. , Large W.A.
Published: July 2012

The effect of frusemide, ethacrynic acid and indanyloxyacetic acid was investigated on spontaneous calcium‐activated chloride (IC1(ca)) and potassium currents (IK(ca)) in rabbit portal vein cells with the perforated patch technique.

Frusemide (0.3‐1.10 × 10−3 m) reduced the amplitude of spontaneous transient inward chloride currents (STICs) in a concentration‐dependent manner. The degree of inhibition on STIC amplitude was similar between —50 and +30 mV and frusemide did not alter the STIC reversal potential (Erev).

The voltage‐dependent exponential decay of STICs, which is thought to represent closure of chloride channels, was not altered by frusemide.

The amplitude and frequency of spontaneous potassium outward currents (STOCs) were not altered by frusemide. Since both STICs and STOCs are activated by calcium released from intracellular stores these data indicate that frusemide may block directly IC1(ca).

Ethacrynic acid (2–5 × 10−4m) decreased the amplitude of STICs in a concentration‐dependent manner by a similar amount at potentials of — 50 to + 30 mV but did not alter the STIC Erev. However, these concentrations of ethacrynic acid also reduced STOC amplitude and 5 × 10−4 m ethacrynic acid evoked a sustained outward current in most cells at 0 mV; thus ethacrynic acid has a more complex action than simple block of Ic1(Ca).

Indanyloxyacetic acid reduced both STIC amplitude and decay time without affecting STOCs and thus also seems to inhibit directly Ic1(ca). It is discussed whether block of IC1(ca) mediates the vasodilator effect of these agents.
D‐Cycloserine transport in human intestinal epithelial (Caco‐2) cells: mediation by a H + ‐coupled amino acid transporter
Authors: Thwaites David T. , Armstrong Gillian , Hirst Barry H. , Simmons Nicholas L.
Published: July 2012

The ability of D‐cycloserine to act as a substrate for H+/amino acid symport has been tested in epithelial layers of Caco‐2 human intestinal cells.

In Na+‐free media with the apical bathing media held at pH 6.0, D‐cycloserine (20 mM) is an effective inhibitor of net transepithelial transport (Jnet) of L‐alanine (100 μm) and its accumulation (across the apical membrane) in a similar manner to amino acid substrates (L‐alanine, β‐alanine, L‐proline and glycine). In contrast L‐valine was ineffective as an inhibitor for H+/amino acid symport. Both inhibition of L‐alanine Jnet and its accumulation by D‐cycloserine were dose‐dependent, maximal inhibition being achieved by 5–10 mM.

Both D‐cycloserine and known substrates for H+/amino acid symport stimulated an inward short circuit current (Isc) when voltage‐clamped monolayers of Caco‐2 epitheha, mounted in Ussing chambers, were exposed to apical substrate in Na+‐free media, with apical pH held at 6.0. The D‐cycloserine dependent increase in Isc was dose‐dependent with an apparent Km= 15.8 + 2.0 (mean ± s.e.mean) mM, and Vmax = 373±21 nmol cm−2 h−1.

D‐Cycloserine (20 mM) induced a prompt acidification of Caco‐2 cell cytosol when superfused at the apical surface in both Na+ and Na+‐free conditions. Cytosolic acidification in response to D‐cycloserine was dependent upon superfusate pH, being attenuated at pH 8 and enhanced in acidic media.

The increment in Isc with 20 mM D‐cycloserine was non‐additive with other amino acid substrates for H+/amino acid symport.
The enantiomers of zacopride: an intra‐species comparison of their potencies in functional and anxiolytic models
Authors: Bill David J. , Coleman James , Hallett Ian , Middlefell Vicki C. , Rhodes Keith F. , Fletcher Allan
Published: July 2012

The 5‐HT3 receptor antagonist, zacopride, and its enantiomers, R(+)‐zacopride and S(−)−zacopride, were examined in three pharmacological models: (i) 5‐HT‐induced depolarizarion of the mouse isolated vagus nerve preparation, (ii) the 5‐HT‐evoked von Bezold‐Jarisch reflex in the mouse, and (iii) the mouse light:dark box model of anxiety. Other standard 5‐HT3 receptor antagonists were also included for comparison in these studies.

Racemic zacopride, and both of the enantiomers, displayed potent 5‐HT3 receptor antagonist activity in the isolated vagus nerve and in the von Bezold‐Jarisch model. No 5‐HT3 receptor agonist or partial agonist effects of these compounds were detected.

In the isolated vagus nerve, R(+)‐zacopride and ondansetron were surmountable 5‐HT3 receptor antagonists (pA2 values of 9.3 and 8.3, respectively), whereas racemic zacopride, S(—)‐zacopride and tropisetron were insurmountable antagonists, markedly suppressing the maximum response to 5‐HT.

In vivo, racemic zacopride, R(+)‐zacopride, S(—)‐zacopride and WAY 100289 were potent antagonists of the 5‐HT‐evoked von Bezold‐Jarisch reflex, with minimum effective doses (lowest dose required to reduce the reflex by ≥85%; MED85) of 1.0, 3.0, 0.3 and 3.0 μg kg−1, s.c, respectively.

Racemic zacopride, R(+)‐zacopride and S(—)‐zacopride were active in the mouse light:dark box model of anxiety, with similar potencies (minimum effective dose 1 μg kg−1, s.c.) and similar active dose‐ranges (1–1000 μg kg−1, s.c).

The doses of racemic zacopride, R(+)‐zacopride and S(−)−zacopride required to block 5‐HT3 receptors in vivo correlated reasonably well with their potencies in an anxiety model within the same species. In these studies, there was no evidence of a marked difference between the anxiolytic potencies of R(+)‐zacopride and S(—)‐zacopride.
Hypotensive effect of 13‐hydroxylinoleic acid in the rat: mediation via the release of a CGRP‐like mediator from capsaicin‐sensitive nerves
Authors: van Heuven‐Nolsen Dicky , Muis Thea , Engels Ferdi , Henricks Paul A.J. , Buckley Theresa L. , Nijkamp Frans P.
Published: July 2012

The effect of 13‐hydroxylinoleic acid (13‐HODE) on changes in blood pressure in the rat was measured.

13‐HODE (0.1 −100 μg kg−1) had no direct eifect on blood pressure in the rat and had no eifect on histamine (0.1–1000 μg kg−1‐induced changes in blood pressure. In contrast, it was found that 13‐HODE itself induced a decrease in diastolic arterial blood pressure when it was injected intravenously after either a single dose of histamine (10, 100 or 1000 μg kg−1) or after a dose‐response curve of histamine (0.1–1000 μg kg−1).

This hypotensive eifect of 13‐HODE was not observed after administration of the endothelium‐dependent vasodilator, acetylcholine (0.1–10 μg kg−1), the endothelium‐independent vasodilator, sodium nitroprusside (0.1–100 μg kg−1) or the inflammatory mediator, leukotriene B4 (0.1–300 μg kg−1). However, prior injection of bradykinin (0.1–100 μg kg−1) allowed a dose‐dependent hypotensive effect of 13‐HODE to be revealed.

The hypotensive effect of 13‐HODE after histamine and bradykinin could be inhibited by neonatal capsaicin treatment of the rats (50 mg kg−1, s.c. on day 1 and 2 after birth).

Ruthenium red (120 μg kg−1 min−1), an inhibitor of excitatory effects on sensory nerves, and the CGRP antagonist, CGRP8.37 (1–3 μg kg−1 min−1) also inhibited the hypotensive effect of 13‐HODE.

It is concluded that the hypotensive effect of 13‐HODE in the rat after histamine and bradykinin is due to the release of a CGRP‐like substance from sensory nerves. These results highlight the possibility that endogenous 13‐HODE could be involved in the neurogenic regulation of blood pressure.