bluuebunny/crossref_metadata_2025 huggingface dataset:
Induction and potential biological relevance of a Ca2+‐independent nitric oxide synthase in the myocardium
Authors: Schulz R. , Nava E. , Moncada S.
Published: July 2012

We have investigated whether the myocardium and isolated cardiac myocytes can express a Ca2+‐independent NO synthase after treatment with endotoxin or cytokines. Nitric oxide synthesis was measured in cytosols from the left ventricular wall from rats treated with endotoxin, or from freshly isolated myocytes from adult rats treated in vitro with cytokines.

Cytosols from the ventricle of saline‐treated control animals showed only Ca2+‐dependent NO synthesis. After treatment with endotoxin, the expression of an inducible, Ca2+‐independent NO synthase was observed. The activity of this enzyme was maximal at 6 h and returned towards control levels by 18 h; no alterations occurred in the Ca2+‐dependent NO synthase activity. Parallel to this enzyme induction there was an increase in myocardial guanosine 3′:5′‐cyclic monophosphate (cyclic GMP) and plasma nitrite and nitrate (NO−x). All these changes were prevented by pretreatment of the rats with dexamethasone.

Myocytes possessed Ca2+‐dependent NO synthase activity and expressed, after treatment with tumour necrosis factor‐α (TNF‐α) and interleukin‐1β (IL‐1β), a Ca2+‐independent NO synthase, the induction of which was prevented by dexamethasone and cycloheximide.

Since increases in cyclic GMP levels in the heart are associated with reduced myocardial contractility, it is possible that the enhanced production of NO by a Ca2+‐independent enzyme accounts, at least in part, for the depression of myocardial contractility seen in septic shock, cardiomyopathies, allograft rejection, burn trauma, as well as during anti‐tumour therapy with cytokines.
Pharmacological characterization of angiotensin‐induced depolarizations of rat superior cervical ganglion in vitro
Authors: Hawcock A.B. , Barnes J.C. , Michel A.D.
Published: July 2012

The depolarizing responses to angiotensin II and angiotensin III of the rat superior cervical ganglion have been characterized in vitro, by the use of peptidase inhibitors, peptide and non‐peptide antagonists and dithiothreitol (DTT).

Angiotensin II and III depolarized the ganglion in a concentration‐related manner. Angiotensin II was approximately 30 fold more potent than angiotensin III.

The endopeptidase inhibitor, bacitracin, increased the potency of angiotensin II and III by approximately 4 and 20 fold respectively. The aminopeptidase inhibitor, amastatin, further increased the potency of angiotensin III (but not angiotensin II) by approximately 4 fold. In the presence of bacitracin and amastatin, angiotensin II and III were equipotent.

The peptide antagonist [Il7]angiotensin III (0.01–0.3 μm) produced a non‐parallel rightward displacement of the angiotensin II concentration‐response curve, with a suppression of the maximum response. The potency of [Ile7]angiotensin III was increased by bacitracin and amastatin.

The AT1‐selective non‐peptide antagonist losartan (DuP 753; 0.03 and 0.1 μm) produced a parallel rightward displacement of the angiotensin II concentration‐response curve, with an apparent pKB of 8.3 ± 0.1. A higher concentration of losartan (0.3 μm) depressed the maximum agonist response by 32 ± 6.5%, possibly reflecting non‐competitive behaviour of the antagonist. The potency of losartan was not influenced by bacitracin.

The AT2‐selective non‐peptide antagonist, PD123177 (3 μm) failed to antagonize the angiotensin II‐induced depolarizations.

DTT (1 mm) produced a 22% reduction of the maximum response to angiotensin II.

We conclude that the angiotensin II‐induced depolarizations of the rat superior cervical ganglion are mediated by angiotensin II receptors of the AT1 subclass. The ability of peptidase inhibitors to modify the potency of peptide agonists and antagonists highlights the difficulties associated with the use of peptide agents to characterize angiotensin II receptors in this preparation.
Separation of putative α1A‐ and α1B‐ adrenoceptor mediated components in the tension response of the rat vas deferens to electrical field stimulation
Authors: Mallard N.J. , Marshall R.W. , Sithers A.J. , Spriggs T.L.B.
Published: July 2012

The effects of the putative α1B‐adrenoceptor antagonist, chloroethylclonidine (CEC), on tension responses of the rat isolated whole vas deferens to single and multiple pulses of electrical field stimulation have been evaluated by use of a microcomputer system which enables the averaging of like‐responses throughout their time course.

CEC (10−7 to 3 × 10−6 m) selectively and in a concentration‐dependent manner blocked the noradrenergic component of the response to a single field stimulus in the absence or presence of nifedipine (10−5 m, which blocked the purinergic but not the noradrenergic component of the response). The concentration‐response curve of the vas to exogenously‐applied noradrenaline (NA) was unaffected by CEC (10−6 m) but was flattened by nifedipine (10−5 m).

The tension response to 10 Hz trains of pulses was biphasic, with an early (< 2 s) and a plateau (> 4 s) phase. We deduce from our pharmacological analysis that the early phase contains a putative α1B‐adrenoceptor component (susceptible to CEC or prazosin but not to nifedipine) and a P2‐purinoceptor component (susceptible to suramin or nifedipine) whereas the plateau phase contains an α1A‐adrenoceptor component (susceptible to prazosin or nifedipine but not to CEC) and a P2‐purinoceptor component (susceptible to suramin or nifedipine).

We suggest that the putative α1B‐adrenoceptors may be functionally confined to the synaptic region whereas the putative α1A‐adrenoceptors are excluded from this region. Trains of pulses would allow NA to accumulate and spill out beyond the synaptic region to reach and activate the putative α1A‐adrenoceptors.
Non‐specific activity of (±)‐CP‐96,345 in models of pain and inflammation
Authors: Nagahisa Atsushi , Asai Rinko , Kanai Yoshihito , Murase Akio , Tsuchiya‐Nakagaki Megumi , Nakagaki Toshiyuki , Shieh Tiee‐Cherng , Taniguchi Kana
Published: July 2012

The non‐peptide NK1 receptor antagonist, CP‐96,345, and its 2R,3R enantiomer CP‐96,344, which is not an NK1 receptor antagonist (IC50 > 10 μm), were evaluated for antinociceptive and anti‐inflammatory activities in several classical models of pain and inflammation in the rat. Both CP‐96,345 and CP‐96,344 reduced carrageenin‐induced paw oedema and hyperalgesia, and attenuated the second phase of formalin‐induced paw licking with equal potency. These results indicate that NK1 antagonism is not responsible for the activity of (±)‐CP‐96,345 in the above animal models.
Calmodulin antagonists inhibit endothelium‐dependent hyperpolarization in the canine coronary artery
Authors: Nagao Tetsuhiko , Illiano Stephane , Vanhoutte Paul M.
Published: July 2012

The effects of the calmodulin antagonists, calmidazolium and fendiline were investigated on endothelium‐dependent hyperpolarization in the canine coronary artery. The membrane potential of vascular smooth muscle cells was measured with the microelectrode technique.

Smooth muscle cells of the canine coronary artery had a resting membrane potential of −50 mV. Bradykinin and the Ca2+‐ionophore, A23187, induced concentration‐ and endothelium‐dependent hyperpolarization. The hyperpolarization induced by a supramaximal concentration of bradykinin (10−6 m) reached approximately 20 mV.

Calmidazolium (10−5 m) and fendiline (10−4 m) inhibited hyperpolarization induced by bradykinin and A23187. By contrast, calmidazolium did not affect the hyperpolarization induced by lemakalim, an opener of ATP‐sensitive K+‐channels.

These observations suggest that calmodulin is involved in the generation of endothelium‐dependent membrane hyperpolarization of vascular smooth muscle.
Endothelium‐dependent relaxation and noradrenaline sensitivity in mesenteric resistance arteries of streptozotocin‐induced diabetic rats
Authors: Taylor Paul D. , McCarthy Andrew L. , Thomas Chris R. , Poston Lucilla
Published: July 2012

Noradrenaline sensitivity and acetylcholine‐induced relaxation were investigated in mesenteric resistance arteries of control and streptozotocin‐induced diabetic rats.

The diabetic rats demonstrated enhanced vascular sensitivity to noradrenaline compared with age‐matched controls (pEC50 5.99 ± 0.06 for diabetic rats, n = 25, versus 5.82 ± 0.03 for controls, n = 45, P < 0.05).

Significant impairment of acetylcholine‐induced relaxation was observed in arteries from the diabetic animals compared with controls (pEC50 6.81 ± 0.17 for diabetic rats, n = 21, versus 7.54 ± 0.17 for controls, n = 45, P < 0.001).

The difference between acetylcholine‐induced relaxation in diabetic and control arteries remained in the presence of 10 μm indomethacin (pEC50 6.41 ± 0.11 for diabetic rats, n = 16, versus 7.59 ± 0.08 for controls, n = 20, P < 0.001).

The nitric oxide synthase inhibitor, NG‐monomethyl‐m‐arginine (l‐NMMA, 1 mm) produced profound inhibition of acetylcholine‐induced relaxation in diabetic arteries but partial inhibition in controls. The incomplete inhibition of acetylcholine‐induced relaxation by m‐NMMA in the control arteries was the result of ineffective inhibition of nitric oxide synthase since an alternative inhibitor, NG‐nitro‐l‐arginine methyl ester (l‐NAME, 0.1 mm), led to similar inhibition to that seen in the diabetic arteries with l‐NMMA. The endothelium‐derived relaxing factor (EDRF)‐mediated component of acetylcholine‐induced relaxation determined by use of the nitric oxide synthase inhibitors was, therefore, apparently reduced in diabetic rats compared with control animals.

6 In further experiments l‐NAME was found to enhance the response to noradrenaline in control rats but not in diabetic animals, suggesting that the abnormal response to noradrenaline in the diabetic animals was also due to reduced EDRF release.

7 Nitroprusside‐induced relaxation (endothelium‐independent) was similar in arteries from control and diabetic rats (pEC50 7.61 ± 0.13 for diabetic arteries, n = 18, versus 7.68 ± 0.15 in the controls, n = 20, P not significant).

8 These results suggest that endothelial function is abnormal in mesenteric resistance arteries of streptozotocin‐induced diabetic rats and that this is predominantly due to reduced EDRF release.
Control of cyclic AMP levels in primary cultures of human tracheal smooth muscle cells
Authors: Hall I.P. , Widdop S. , Townsend P. , Daykin K.
Published: July 2012

[3H]‐adenosine 3′:5′‐cyclic monophosphate ([3H]‐cyclic AMP) responses were studied in primary cultures of human tracheal smooth muscle cells derived from explants of human trachealis muscle and in short term cultures of acutely dissociated trachealis cells.

Isoprenaline induced concentration‐dependent [3H]‐cyclic AMP formation wtih an EC50 of 0.2 μm. The response to 10 μm isoprenaline reached a maximum after 5–10 min stimulation and remained stable for periods of up to 1 h. After 10 min stimulation, 1 μm isoprenaline produced a 9.5 fold increase over basal [3H]‐cyclic AMP levels. The response to isoprenaline was inhibited by ICI 118551 (10 nm), (apparent KA 1.9 × 109 m−1) indicating the probable involvement of a β2‐adrenoceptor in this response in human cultured tracheal smooth muscle cells. However, with 50 nm ICI 118551 there was a reduction in the maximum response to isoprenaline. Prostaglandin E2 also produced concentration‐dependent [3H]‐cyclic AMP formation (EC50 0.7 μm, response to 1 μm PGE2 6.4 fold over basal).

Forskolin (1 nm‐100 μm) induced concentration‐dependent [3H]‐cyclic AMP formation in these cells. A 1.6 fold (over basal) response was also observed following stimulation with NaF (10 mm).

The nonselective phosphodiesterase inhibitor 3‐isobutyl‐1‐methylxanthine (IBMX) (0.1 mm) and the type IV, cyclic AMP selective, phosphodiesterase inhibitor rolipram (0.1 mm) both elevated basal [3H]‐cyclic AMP levels by 1.8 and 1.5 fold respectively. IBMX (1–100 μm) and low concentrations of rolipram (< 10 μm), also potentiated the response to 1 μm isoprenaline. Inhibitors of the type III phosphodiesterase isoenzyme (SK&F 94120 and SK&F 94836) were without effect upon basal or isoprenaline‐stimulated cyclic AMP responses in these cells.

Carbachol (1 nm‐100 μm) produced concentration‐dependent inhibition of the [3H]‐cyclic AMP response to 1 μm isoprenaline in human cultured tracheal smooth muscle cells (IC50 0.24 μm). Carbachol (1 μm) inhibited the [3H]‐cyclic AMP response to 1 μm isoprenaline by 60%. This effect of carbachol was itself inhibited by atropine (50 nm) (KA 2.3 × 109 m−1) indicating the involvement of a muscarinic receptor.

6 These results show that primary cultures of human tracheal smooth muscle cells demonstrate cyclic AMP responses to direct receptor stimulation, adenylyl cyclase activation and inhibition with nonselective and type IV‐selective cyclic AMP phosphodiesterase isoenzyme inhibitors, and that the cyclic AMP response to isoprenaline can be inhibited by muscarinic receptor stimulation.
A pertussis toxin‐sensitive mechanism of endothelin action in porcine coronary artery smooth muscle
Authors: Kasuya Yoshitoshi , Takuwa Yoh , Yanagisawa Masashi , Masaki Tomoh , Goto Katsutoshi
Published: July 2012

Endothelin‐1 (ET‐1)‐induced contraction of porcine coronary artery strips may be mediated via at least two intracellular signalling mechanisims, the activation of dihydropyridine‐sensitive voltage‐dependent Ca2+ channels and the stimulation of phosphoinositide breakdown. Here we have investigated the possible involvement of pertussis toxin (PT)‐sensitive guanosine‐5′‐triphosphate (GTP)‐binding proteins (G‐proteins) in ET‐1‐induced activation of these two signalling pathways in porcine coronary artery smooth muscle.

Increase in extracellular K+ concentration (10, 15 mm) shifted the dose‐response relationship for the ET‐1‐induced contraction to the left.

The dihydropyridine Ca2+ channel blocker, nifedipine (10−8 m), induced a rightward shift in the dose‐response curve for ET‐1. Pretreatment of the arterial strips with PT (0.1 μg ml−1) induced a similar rightward shift of the ET‐1 dose‐response curve but not of the KCl response. Nifedipine (10−8 m) did not further attenuate the ET‐1‐induced contraction in the PT‐pretreated strips.

The pretreatment with PT significantly reduced 45Ca2+ uptake of the arterial strips stimulated by ET‐1, but had no effect on ET‐1‐induced production of inositol phosphates.

The contractile response of the arterial strips to phorbol dibutyrate, an active phorbol ester, was not significantly affected by 10−8 m nifedipine.

6 We confirmed that the pretreatment of the tissue with PT induced ADP‐ribosylation of a 41 kDa membrane protein.

7 These findings indicate that activation of dihydropyridine‐sensitive voltage‐dependent Ca2+ channels by ET‐1 in this tissue is mediated via a PT‐sensitive G‐protein in a manner apparently independent of the ET‐1‐induced activation of protein kinase C. It is concluded that the action of ET‐1 in porcine coronary artery is mediated via two distinct signal transduction pathways, which are coupled to PT‐sensitive and PT‐insensitive GTP‐binding proteins, respectively.
Agonist analysis of 2‐(carboxycyclopropyl)glycine isomers for cloned metabotropic glutamate receptor subtypes expressed in Chinese hamster ovary cells
Authors: Hayashi Yasunori , Tanabe Yasuto , Aramori Ichiro , Masu Masayuki , Shimamoto Keiko , Ohfune Yasufumi , Nakanishi Shigetada
Published: July 2012

2‐(Carboxycyclopropyl)glycines (CCGs) are conformationally restricted glutamate analogues and consist of eight isomers including l‐ and d‐forms. The agonist potencies and selectivities of these compounds for metabotropic glutamate receptors (mGluRs) were studied by examining their effects on the signal transduction of representative mGluR1, mGluR2 and mGluR4 subtypes in Chinese hamster ovary cells expressing the individual cloned receptors.

Two extended isomers of l‐CCG, l‐CCG‐I and l‐CCG‐II, effectively stimulated phosphatidylinositol hydrolysis in mGluR1‐expressing cells. The rank order of potencies of these compounds was l‐glutamate > l‐CCG‐I > l‐CCG‐II.

l‐CCG‐I and l‐CCG‐II were effective in inhibiting the forskolin‐stimulated adenosine 3′:5′‐cyclic monophosphate (cyclic AMP) accumulation in mGluR2‐expressing cells. Particularly, l‐CCG‐I was a potent agonist for mGluR2 with an EC50 value of 3 × 10−7 m, which was more than an order of potency greater than that of l‐glutamate.

l‐CCG‐I evoked an inhibition of the forskolin‐stimulated cyclic AMP production characteristic of mGluR4 with a potency comparable to l‐glutamate.

In contrast to the above compounds, the other CCG isomers showed no appreciable effects on the signal transduction involved in the three mGluR subtypes.

6 This investigation demonstrates not only the importance of a particular isomeric structure of CCGs in the interaction with the mGluRs but also a clear receptor subtype specificity for the CCG‐receptor interaction, and indicates that the CCG isomers would serve as useful agonists for investigation of functions of the mGluR family.
Capsazepine: a competitive antagonist of the sensory neurone excitant capsaicin
Authors: Bevan S. , Hothi S. , Hughes G. , James I.F. , Rang H.P. , Shah K. , Walpole C.S.J. , Yeats J.C.
Published: July 2012

Capsazepine is a synthetic analogue of the sensory neurone excitotoxin, capsaicin. The present study shows the capsazepine acts as a competitive antagonist of capsaicin.

Capsazepine (10 μm) reversibly reduced or abolished the current response to capsaicin (500 nm) of voltage‐clamped dorsal root ganglion (DRG) neurones from rats. In contrast, the responses to 50 μm γ‐aminobutyric acid (GABA) and 5 μm adenosine 5′‐triphosphate (ATP) were unaffected.

The effects of capsazepine were examined quantitatively with radioactive ion flux experiments. Capsazepine inhibited the capsaicin (500 nm)‐induced 45Ca2+ uptake in cultures of rat DRG neurones with an IC50 of 420 ± 46 nm (mean ± s.e.mean, n = 6). The 45Ca2+ uptake evoked by resiniferatoxin (RTX), a potent capsaicin‐like agonist was also inhibited. (Log concentration)‐effect curves for RTX (0.3 nm‐1 μm) were shifted in a competitive manner by capsazepine. The Schild plot of the data had a slope of 1.08 ± 0.15 (s.e.) and gave an apparent Kd estimate for capsazepine of 220 nm (95% confidence limits, 57–400 nm).

Capsazepine also inhibited the capsaicin‐ and RTX‐evoked efflux of 86Rb+ from cultured DRG neurones. The inhibition appeared to be competitive and Schild plots yielded apparent Kd estimates of 148 nm (95% confidence limits, 30–332 nm) with capsaicin as the agonist and 107 nm (95% confidence limits, 49–162 nm) with RTX as agonist.

A similar competitive inhibition by capsazepine was seen for capsaicin‐induced [14C]‐guanidinium efflux from segments of adult rat vagus nerves (apparent Kd = 690 nm; 95% confidence limits, 63 nm‐1.45 μm). No significant difference was noted in the apparent Kd estimates for capsazepine in assays on cultured DRG neurones and vagus nerve as shown by the overlap in the 95% confidence limits.

6 Capsazepine, at concentrations up to 10 μm, had no significant effects on the efflux of 86Rb+ from cultured DRG neurones evoked either by depolarization with high (50 mm) K+ solutions or by acidification of the external medium to pH 5.0–5.6. Similarly capsazepine had no significant effect on the depolarization (50 mm KCl)‐induced efflux of [14C]‐guanidinium from vagus nerve preparations.

7 Ruthenium Red was also tested for antagonism against capsaicin evoked [14C]‐guanidinium release from vague nerves and capsaicin induced 45Ca2+ uptake in cultures of DRG neurones. In contrast to capsazepine the inhibition by Ruthenium Red (10–500 nm in DRG and 0.5–10 μm in vagus nerve experiments) was not consistent with a competitive antagonism, but rather suggested a more complex, non‐competitive inhibition.
Low dihydropyridine receptor density in vasa deferentia of castrated rats
Authors: Castillo C.J.F. , Lafayette S. , Caricati‐Neto A. , Sette M. , Jurkiewicz N.H. , García A.G. , Jurkiewicz> A.
Published: July 2012

Radioligand binding studies in crude membrane preparations of vasa deferentia of normal rats, with the 1,4‐dihydropyridine (+)‐[3H]‐PN200–110 (isradipine) showed typical saturation isotherms. The binding exhibited a KD of 259 ± 60 pm and Bmax of 144 ± 20 fmol mg−1 protein. The low KD and the stereoselective displacement of (+)‐[3H]‐PN200–110 binding by (+)‐ and (−)‐PN200–110 and by nifedipine suggests that these tissues contain dihydropyridine receptors probably coupled to voltage‐sensitive, L‐type calcium channels. In membrane preparations from vasa deferentia from rats castrated 30 days previously the maximum specific binding was 25 ± 10 fmol mg−1 protein, representing only 11% of total binding; thus, the calculation of reliable KD values was not feasible. These findings suggest that a testicular hormone, possibly testosterone, plays an important role in the regulation of dihydropyridine‐sensitive, voltage‐dependent calcium channels in the rat vas deferens.
Direct action of BRL 38227 and glibenclamide on intracellular calcium stores in cultured airway smooth muscle of rabbit
Authors: Chopra Lorna C. , Twort Charles H.C. , Ward Jeremy P.T.
Published: July 2012

The effects of BRL 38227 and glibenclamide on intracellular calcium stores were investigated in permeabilized cultured airway smooth muscle cells of the rabbit using 45Ca effluxes. BRL 38227 (10 μm) reduced loading of the inositol 1,4,5‐trisphosphate (InsP3)‐sensitive intracellular store by 26.5% ± 1.0; this effect was antagonized by 1 μm glibenclamide. BRL 38227 itself did not release calcium and had no effect on guanosine 5′‐0‐(3‐thiotriphosphate)‐induced calcium release. Glibenclamide (≥5 μm) also reduced calcium loading of the intracellular store, and enhanced calcium release. These results suggest that BRL 38227 has a direct effect on intracellular calcium handling.
Hepoxilins sensitize blood vessels to noradrenaline—stereospecificity of action
Authors: Laneuville Odette , Couture Réjean , Pace‐Asciak Cecil R.
Published: July 2012

. The vascular activity of two stereoisomers of hepoxilin A3 (HxA3) (8R and 8S) and of its glutathione conjugate, hepoxilin A3‐C (HxA3‐C) (8R and 8S), was investigated on rat helicoidal strips of thoracic aorta and longitudinal strips of portal vein.

. Neither of the hepoxilins tested had a direct effect on the tone of the aortic strip or on the spontaneous contractions of the portal vein. However, the noradrenaline (NA)‐induced response of these vessels, as expressed by the dose required for half maximal contraction, (EC50) was greater in HxA3 (8S)‐ and HxA3‐C (8R)‐treated aorta. Increased frequency and strength of spontaneous contractions of the portal vein were detected at lower concentrations of NA in the presence of hepoxilins.

. The threshold dose for both hepoxilins was 10−8 m and their effect was not dose‐related beyond 10−8 m. The effect of hepoxilin appeared after a 45 min incubation period and could be observed even if the compounds were washed out after 15 min.

. Stereochemical specificity was observed. The 8S isomer of HxA3 was active in potentiating the NA‐induced contraction of these vessels while the 8R isomer was inactive. In contrast, the 8R isomer of HxA3‐C was active while the 8S isomer was inactive. In both tissues, HxA3 (8S) was more potent than its glutathione conjugate, HxA3‐C (8R).

. In calcium‐free buffer or in the presence of a calcium channel blocker (nifedipine 1 μm), no potentiation of NA‐induced contraction by hepoxilins could be observed, suggesting the involvement of extracellular calcium in the actions of hepoxilins.

. These experiments suggest that hepoxilins may be involved in the modulation of vascular tone and contractility.
Myocardial hypertrophy, cardiac β‐adrenoceptors and adenylate cyclase activity during sinoaortic denervation in dogs
Authors: Galinier Michel , Sénard Jean‐Michel , Valet Philippe , Dréan Géraldine , Planat Valerie , Arias Agustin , Tran Marie‐Antoinette , Montastruc Jean‐Louis
Published: July 2012

. The long‐term effects of sinoaortic denervation on the development of left ventricular hypertrophy (assessed by the measurement of the ratio (R): heart weight/total body weight and LVT: left ventricular thickness), myocardial β‐adrenergic receptivity (measured by [125I]‐cyanopindolol binding and adenylate cyclase activity) and plasma catecholamine levels (measured by h.p.l.c.) were investigated in three groups of dogs: normotensive controls (group 1), dogs made hypertensive by sinoaortic denervation and evaluated 1 (group 2) and 18 months (group 3) later.

. Noradrenaline (NA) and adrenaline (A) plasma levels were 461 ± 54 and 85 ± 45 pg ml−1 in controls, 861 ± 185 and 191 ± 23 pg ml−1 in group 2 (P < 0.05). They were normal in group 3 (426 ± 132 and 110 ± 16 pg ml−1).

. R and LVT values were significantly (P < 0.05) higher in sinoaortic denervated dogs (R = 7.7 ± 0.1 and 7.8 ± 0.2; LVT = 13.6 ± 1.3 and 14.2 ± 0.9 mm in groups 2 and 3 respectively) than in normotensive dogs (group 1: R = 6.7 ± 0.1, LVT = 9.3 ± 0.8 mm).

. In group 1, the total number of β‐adrenoceptors (Bmax) was 37 ± 11 and 29 ± 6 fmol mg−1 protein in the left ventricle (LV) and right auricle (RA) respectively. In group 2, Bmax was significantly lower (10 ± 3 in LV and 13 ± 2 fmol mg−1 protein in RA, P < 0.05) than in group 1. There was no difference between group 1 and group 3 (37 ± 3 fmol mg−1 prot in LV and 31 ± 3 fmol mg−1 protein in RA).

. The percentage of β1‐adrenoceptors was 82 ± 4 in LV and 75 ± 5 in RA in group 1. It was significantly lower (P < 0.05) in groups 2 (LV: 33 ± 6 and RA: 33 ± 5) and 3 (LV: 59 ± 3 and RA: 55 ± 4).

. Basal values of adenylate cyclase activity in LV significantly decreased after sinoaortic denervation. Isoprenaline alone or in the presence of a β2‐adrenoceptor antagonist (ICI 118551, 1 μm) failed to stimulate adenylate cyclase activity 1 (but not 18) month after sinoaortic denervation.

. These data show that sinoaortic denervation is associated with left ventricular hypertrophy which appears early (1 month) and persists until 18 months despite the normalization of plasma catecholamine levels. The total number of myocardial β‐adrenoceptors is closely related to catecholamine levels but a selective decrease in β1‐adrenoceptors is observed during cardiac hypertrophy. The fall in basal adenylate cyclase activity suggests that cardiac hypertrophy is associated with an impairment of transmembrane signalling.
Differential inhibitory effects of opioids on cigarette smoke, capsaicin and electrically‐induced goblet cell secretion in guinea‐pig trachea
Authors: Kuo H.‐P. , Rohde J.A.L. , Barnes P.J. , Rogers D.F.
Published: July 2012

Goblet cell secretion in guinea‐pig airways is under neural control. Opioids have previously been shown to inhibit neurogenic plasma exudation and bronchoconstriction in guinea‐pig airways. We have now examined the effects of morphine and opioid peptides on tracheal goblet cell secretion induced by either electrical stimulation of the cervical vagus nerves, exogenous capsaicin, or acute inhalation of cigarette smoke. The degree of goblet cell secretion was determined by a morphometric method and expressed as a mucus score which is inversely related to mucus discharge.

Morphine, 1 mg kg−1, completely blocked goblet cell secretion induced by electrical stimulation of the vagus nerves. Morphine also inhibited the response to cigarette smoke given either at a low dose (10 breaths of 1:10 diluted in air), which principally activates cholinergic nerves, or at a high dose (20 breaths of undiluted), which activates capsaicin‐sensitive sensory nerves, by 100% and 73% respectively. In contrast, morphine had no significant inhibitory effect on capsaicin‐induced goblet cell secretion. The inhibitory effect of morphine was reversed by naloxone.

Selective μ‐ or δ‐opioid receptor agonists, [d‐Ala2, NMePhe4, Glyol5]enkephalin (DAMGO) or [d‐Pen2, d‐Pen5]enkephalin (DPDPE) respectively, caused a dose‐related inhibition of low dose cigarette smoke‐induced goblet cell discharge, with DPDPE more potent than DAMGO. A κ‐receptor agonist, trans‐3,4‐dichloro‐N‐methyl‐N‐(2‐(1‐pyrollidinyl)cyclohexyl) benzeneacetamine (U‐50,488H), had no inhibitory effect. DPDPE had no inhibitory effect on goblet cell secretion induced by exogenous methacholine.

DAMGO dose‐dependently blocked the response to high dose cigarette smoke with a maximal inhibition of 95% at 2 × 10−7 mol kg−1. Neither DPDPE nor U‐50,488H had any significant inhibitory effect. The increase in goblet cell secretion induced by exogenous substance P was not affected by DAMGO.

We conclude that opioids inhibit neurally‐mediated goblet cell secretion via actions at prejunctional δ‐ and μ‐receptors on cholinergic nerves and at μ‐receptors on sensory nerve endings, and that capsaicin activation of sensory nerves is via a different mechanism from that of electrical or cigarette smoke activation.
Evidence for multiple endothelin receptors in the guinea‐pig pulmonary artery and trachea
Authors: Cardell Lars Olaf , Uddman Rolf , Edvinsson Lars
Published: July 2012

The responses of the three peptides, endothelin 1 (ET‐1), endothelin 2 (ET‐2) and endothelin 3 (ET‐3) were analysed on isolated circular segments of pulmonary arteries and trachea from the guinea‐pig.

In the pulmonary artery, the vasomotor responses to the endothelins, expressed as the maximum contraction (Emax%), had the order ET‐1 > ET‐2 > ET‐3 while the order of potency (pD2) was ET‐1 = ET‐2 > ET‐3. ET‐1 and ET‐2 caused cross‐desensitization, but did not affect the responses to ET‐3. ET‐3 did not cause cross‐desensitization to ET‐1 or ET‐2 although it induced homologous desensitization. Finally, the effects of ET‐1 and ET‐2 were additive to those of ET‐3. The additive effect of ET‐3 to those of ET‐1 or ET‐2 was more difficult to demonstrate, given the profound contraction produced by ET‐1 and to a lesser extent by ET‐2.

In the trachea, the rank order of potency, additivity and desensitization were different from the pulmonary artery. Basically, all three peptides were equipotent but less potent than ET‐1 in the artery. There was no evidence for additivity and only a slight tendency to tachyphylaxis was seen.

The guinea‐pig pulmonary artery appears to be endowed with one receptor type which is sensitive to ET‐1/ET‐2 and with another receptor type which responds preferentially to ET‐3. In the trachea, neither of these receptors appears to be present since all three peptides apparently act on a homogeneous population of receptors with characteristics different from those of the two arterial receptors. This suggests a third non‐isopeptide selective type of endothelin receptor.
Effects of systemic non‐steroidal anti‐inflammatory drugs on nociception during tail ischaemia and on reperfusion hyperalgesia in rats
Authors: Gelgor Linda , Butkow Neil , Mitchell Duncan
Published: July 2012

We have investigated the effects of five non‐steroidal anti‐inflammatory drugs (NSAIDs) on nociception during ischaemia and on reperfusion hyperalgesia in rats.

We induced tail ischaemia in conscious rats by applying a tourniquet at the base of the tail until the rats exhibited co‐ordinated escape behaviour when we released the tourniquet.

We assessed hyperalgesia by measuring the tail flick latency following tail immersion in water at 49°C, before applying and immediately after releasing the tourniquet, and then at 30 min intervals for 2 h.

Intraperitoneal injection of NSAIDs prior to applying the tourniquet had no effect on the co‐ordinated escape behaviour during ischaemia, nor on tail flick latency in the absence of prior ischaemia. However all the drugs attenuated reperfusion hyperalgesia in a log dose‐dependent manner. Doses required to abolish hyperalgesia, were indomethacin 5 mg kg−1, diclofenac sodium 42 mg kg−1, ibuprofen 54 mg kg−1, dipyrone 168 mg kg−1 and paracetamol 170 mg kg−1.

We conclude that the mechanisms underlying nociception during ischaemia are not the same as those underlying reperfusion hyperalgesia. Moreover our procedure provides a rapid and more humane method for measuring the antinociceptive potency of NSAIDs.
Blockade of delayed rectifier K+ currents in neuroblastoma × glioma hybrid (NG 108–15) cells by clofilium, a class III antidysrhythmic agent
Authors: Reeve Helen L. , Peers Chris
Published: July 2012

The whole‐cell patch‐clamp technique was used to examine the effects of the class III antidysrhythmic agent, clofilium, on voltage‐activated delayed rectifier K+ currents (IKv) in undifferentiated mouse neuroblastoma × rat glioma hybrid (NG 108–15) cells. Ca2+‐activated K+ currents also seen in these cells were abolished by bath application of 4 mm Co2+.

Bath application of clofilium (0.3 to 70 μm) caused dose‐dependent, irreversible inhibition of IKv in these cells. Under control conditions, activated currents were sustained during 200 ms depolarizing steps, but in the presence of clofilium, or after its wash‐out, currents were reduced in amplitude and showed a time‐dependent decay.

Clofilium blockade of IKv was voltage‐dependent: the degree of current inhibition increased with increasing depolarizations. The transient nature of IKv seen in the presence of clofilium was also more apparent at higher test potentials.

The effects of clofilium were use‐dependent: when cells were left unstimulated during drug application, and then depolarizations were resumed, several pulses were required for clofilium blockade to reach a steady level. Similar results were obtained post‐clofilium, when cells were unstimulated during application and then removal of clofilium, suggesting that although the blocking action of the drug was use‐dependent, it bound to the closed, delayed rectifier K+ channel.

High concentrations (100 or 300 μm) of sotalol, another class III antidysrhythmic agent, were without discernible effects on IKv in NG 108–15 cells.

The effects of clofilium on a neuronal IKv described here, and its possible mechanism of action, are compared with previously reported effects of clofilium on the cardiac IKv.
Adenosine modulation of calcium currents in postganglionic neurones of avian cultured ciliary ganglia
Authors: Bennett Max R. , Kerr R. , Khurana G.
Published: July 2012

Calcium currents in postganglionic neurones of cultured 7‐ to 10‐day embryonic avian ciliary ganglia were analyzed under whole‐cell voltage‐clamp and their modulation by 2‐chloroadenosine determined.

In the presence of tetrodotoxin (200 nm) in the medium to block the Na+ current and CsCl (105 mm) in the patch‐clamp electrode to block the K+ current, two different components of the calcium currents (transient and sustained) were identified on the basis of their voltage‐dependent kinetics as well as their sensitivity to the dihydropyridine agonist Bay K 8644 and antagonist nifedipine.

The sustained current inactivated very slowly (τ > 1000 ms; for test potentials from − 20 mV to + 40 mV) but was reactivated at a holding potential (Vh) of − 40 mV. The current was increased on average over 50% by 1 μm of Bay K 8644 at a test potential of 0 mV and decreased over 35% by 1 μm of nifedipine.

The transient current inactivated slowly (τ < 200 ms; for test potentials from −20 mV to +40 mV), and could be completely reactivated at a Vh of − 80 mV. This current was unaffected by Bay K 8644 (1 μm) but reduced on average by 8% with nifedipine (1 μm).

The sustained and transient currents were decreased more than 70% by 5 μm of ω‐conotoxin and decreased more than 50% by 250 μm verapamil.

2‐Chloroadenosine (1 μm) decreased the transient current by over 50% and the sustained current by less than 10%. In the presence of nifedipine (1 μm), 2‐chloroadenosine decreased the transient current by over 30% and the remaining sustained current by 35%. In the presence of 8‐phenyltheophylline (10 μm), 2‐chloroadenosine no longer decreased either the transient or sustained currents but did have a slight potentiating effect on both the transient and sustained currents.

These observations of the effects of 2‐chloroadenosine on the transient and sustained currents are discussed in relation to the different calcium channel types at preganglionic nerve terminals.
Combined dose‐ratio analysis of cholecystokinin receptor antagonists, devazepide, lorglumide and loxiglumide in the guinea‐pig gall bladder
Authors: Bishop L.A. , Gerskowitch V.P. , Hull R.A.D. , Shankley N.P. , Black J.W.
Published: July 2012

Interactions between cholecystokinin octapeptide (CCK‐8) and CCKA‐receptor antagonists derived from benzodiazepines (devazepide) and glutamic acid (lorglumide and loxiglumide) have been examined in an improved bioassay using the guinea‐pig, isolated, gall bladder preparation.

The presence of CCKB‐receptors in the assay was provisionally‐ruled out on the basis of the low potency of pentagastrin in the assay. By applying analyses of both agonism and antagonism, pentagastrin was shown to behave as a partial agonist at the CCKA‐receptor.

Devazepide, lorglumide and loxiglumide behaved as simple competitive antagonists of CCKA‐receptors and pKB values of 9.98, 7.59 and 7.07 were estimated, respectively.

Application of a combined dose‐ratio analysis to the interactions between CCK‐8 and combinations of devazepide/lorglumide and devazepide/loxiglumide indicated that these molecules behave as syntopic, competitive, antagonists at the CCKA‐receptor.

We conclude that the guinea‐pig gall bladder assay contains a homogeneous population of CCKA‐receptors and offer an explanation for the differences between our results and those obtained recently by Maubach et al. (1991) which were taken as preliminary evidence for CCKA‐receptor heterogeneity.
The effect of monoclonal antibodies to calcitonin gene‐related peptide (CGRP) on CGRP‐induced vasodilatation in pig coronary artery rings
Authors: Shaw N.E. , Foulkes R. , Andrew D.P. , Brown D.T. , Hughes B.
Published: July 2012

The modification of the vasodilator effect of calcitonin gene‐related peptide (CGRP) by a panel of monoclonal antibodies (MAbs), which map to discrete epitopes on the CGRP molecule, was investigated in pig coronary artery rings (PCA). The preparations were pre‐constricted with acetylcholine (3 × 10−7 m) and concentration‐response curves to CGRP (2 × 10−10 − 2.56 × 10−8 m) were obtained in the presence or absence of each MAb.

CGRP caused a concentration‐dependent relaxation of PCAs which reached a maximum (98.2 ± 4.8%, n = 25) at 1.28 × 10−8 m and gave an EC50 of 3.8 ± 0.8 × 10−9 m.

Two MAbs which map to the N‐terminal, CN1 and CRA3, did not affect the CGRP response whilst a third, CRA5, significantly inhibited its effect.

The C‐terminal MAb, CRA2, did not modify the CGRP response whilst, in contrast, CB3 (C‐terminal) potentiated its effect. A similar augmentation of the CGRP‐induced vasodilatation was seen in the presence of the middle‐region MAb, CRA8.

These results suggest that regional specific MAbs can modify the vasodilator effect of CGRP causing either inhibition (CRA5, N‐terminal) or potentiation (CB3, C‐terminal; CRA8, middle region).
Adenosine A1‐receptor stimulation of inositol phospholipid hydrolysis and calcium mobilisation in DDT1 MF‐2 cells
Authors: White Teresa E. , Dickenson John M. , Alexander Stephen P.H. , Hill Stephen J.
Published: July 2012

. The effect of adenosine receptor‐stimulation on inositol phospholipid hydrolysis and calcium mobilization has been investigated in the hamster vas deferens smooth muscle cell line DDT1 MF‐2.

. Adenosine receptor stimulation increased the accumulation of total [3H]‐inositol phosphates in DDT1 MF‐2 cells prelabelled with [3H]‐myo‐inositol. The rank order of agonist potencies was N6‐cyclo‐pentyladenosine > 5′‐N‐ethylcarboxamidoadenosine > 2‐chloroadenosine > adenosine.

. The response to 2‐chloroadenosine was antagonized by the antagonists 8‐cyclopentyl‐1,3‐dipropylxanthine (KD 1.2 nm), PD 115,199 (KD 39 nm) and 8‐phenyltheophylline (KD 31 nm).

. The inositol phosphate response to 2‐chloradenosine (10 μm) was not significantly altered when the extracellular Ca2+ ion concentration was reduced from 2.4 mm to 1.2 mm or 0.6 mm. Under calcium‐free conditions, however, a reduced but still significant response to 2‐chloroadenosine was evident (39 ± 10% of the response in calcium‐containing medium).

. The 5‐lipoxygenase inhibitor AA861 (10 and 100 μm) inhibited the inositol phosphate response to 2‐chloroadenosine by 40 ± 9% and 60 ± 4% respectively. The cyclo‐oxygenase inhibitor, indomethacin, however, was without significant effect at 1 μm.

. 2‐Chloroadenosine stimulated an increase in intracellular free Ca2+ ion concentration in fura‐2 loaded DDT1 MF‐2 cells in calcium‐free medium containing 0.1 mm EGTA, which could be inhibited by the adenosine A1‐receptor antagonist 8‐cyclopentyl‐1,3‐dipropylxanthine (0.1 μm).

. These data suggest that adenosine A1‐receptor stimulation results in inositol phospholipid hydrolysis and calcium mobilization from intracellular stores in DDT1 MF‐2 cells.
Pituitary adenylate cyclase activating polypeptide is a potent vasodilator and oedema potentiator in rabbit skin in vivo
Authors: Warren J.B. , Larkin S.W. , Coughlan M. , Kajekar R. , Williams T.J.
Published: July 2012

The effects of pituitary adenylate cyclase activating polypeptide (PACAP) on microvascular blood flow and plasma protein leakage were investigated in rabbit skin in vivo.

Intradermal injection of PACAP38, the 38 amino acid form of the peptide, caused a dose‐dependent increase in blood flow measured by a 133Xe clearance technique. An equivalent increase in blood flow was induced by 10−12 mol per site of PACAP38, 10−12 mol per site of human α‐calcitonin gene‐related peptide (CGRP) and 10−10 mol per site of vasoactive intestinal polypeptide (VIP).

The vasodilator activity of PACAP38 was not significantly different from that of the 27 amino acid form of the peptide, PACAP27, when measured with a laser Doppler flow meter, causing a 104 ± 14% compared with 110 ± 18% increase above basal blood flow at 10−12 mol per site respectively.

At 10−12 mol per site the effect of PACAP38 was longer lasting than that of CGRP. Blood flow remained significantly increased above control at 2 h with PACAP38 (P < 0.05) whereas blood flow after intradermal CGRP had returned to control values by this time.

PACAP38 injected alone had no significant effect on microvascular leakage of 125I‐labelled albumin. However, PACAP38 significantly potentiated bradykinin‐induced oedema where it was approximately 100 fold more potent than VIP.

Oedema potentiation induced by PACAP38 was not inhibited by indomethacin at a dose which did inhibit potentiation of bradykinin‐induced oedema by arachidonic acid.

PACAP38 is at least as potent as other peptides which have been postulated to be involved in the inflammatory response when tested in rabbit skin in vivo. PACAP may contribute to both the hyperaemia and oedema components of inflammation.
Effects of Hoe 140, a bradykinin B2‐receptor antagonist, on renal function in conscious normotensive rats
Authors: Madeddu Paolo , Anania Vittorio , Demontis Maria Piera , Varoni Maria Vittoria , Pisanu Gavino , Troffa Chiara , Tonolo Giancarlo , Glorioso Nicola , Parpaglia Paolo Pinna
Published: July 2012

. The present study was designed to determine if endogenous kinins are involved in the regulation of arterial blood pressure and renal function in conscious rats given deoxycorticosterone enantate (DOC, 25 mg kg−1, s.c., weekly) or vehicle for two weeks.

. The bradykinin B2‐receptor antagonist, d‐Arg[Hyp3,Thi5,d‐Tic7,Oic8]‐bradykinin (Hoe 140), at a dose of 300 μg kg−1, s.c., blocked the hypotensive effect of 300 ng kg−1 bradykinin i.a., but it did not alter the blood pressure lowering action of 300 ng kg−1 acetylcholine or prostaglandin E2. Inhibition of the response to bradykinin persisted up to 6 h after the administration of Hoe 140.

. Administration of 300 μg kg−1 Hoe 140 s.c. four times a day did not alter mean blood pressure, renal blood flow, or renal function in rats given DOC‐vehicle. However, it decreased urinary volume by 70% (from 48.2 ± 3.8 to 14.3 ± 3.7 ml 24 h−1, P < 0.01) and urinary secretion of sodium by 54% (from 1.02 ± 0.05 to 0.47 ± 0.16 mmol 24 h−1, P < 0.01) and potassium by 30% (from 2.93 ± 0.15 to 2.04 ± 0.15 mmol 24 h−1, P < 0.05) in DOC‐treated rats. Mean blood pressure, glomerular filtration rate and total renal blood flow remained unchanged.

. Our results suggest that endogenous kinins play a role in the regulation of renal excretion of water and sodium in the presence of elevated levels of DOC.
Synergistic anti‐nociceptive effect of l‐NG‐nitro arginine methyl ester (l‐NAME) and flurbiprofen in the mouse
Authors: Morgan C.V.J. , Babbedge R.C. , Gaffen Z. , Wallace P. , Hart S.L. , Moore P.K.
Published: July 2012

l‐NG‐nitro arginine methyl ester (l‐NAME) administered i.p. produces anti‐nociception in the mouse assessed by the formalin‐induced paw licking and acetic acid‐induced abdominal constriction models. The non‐steroidal anti‐inflammatory drug (NSAID), flurbiprofen, was similarly anti‐nociceptive in both models.

Combination of a sub‐threshold dose of l‐NAME (10 mg kg−1) with increasing doses of flurbiprofen (25‐ 75 mg kg−1) or a sub‐threshold dose of flurbiprofen (50 mg kg−1) with increasing doses of l‐NAME (10‐ 100 mg kg−1) resulted in potentiated anti‐nociception in the formalin model. Combined therapy with sub‐threshold doses of l‐NAME (10 mg kg−1) and indomethacin (10 mg kg−1) also resulted in significant anti‐nociception. In addition, combining sub‐threshold doses of l‐NAME (12.5 mg kg−1) and flurbiprofen (2 mg kg−1) significantly reduced acetic acid‐induced abdominal constriction.

l‐NAME (10 mg kg−1) administered i.p. caused a significant (approximately 35%) increase in MAP in the urethane‐anaesthetized mouse. Flurbiprofen (50 mg kg−1) was inactive. Combination treatment with l‐NAME (10 mg kg−1) and flurbiprofen (50 mg kg−1) failed to elevate MAP above that observed with l‐NAME alone. Neither l‐NAME (10 mg kg−1) nor flurbiprofen (50 mg kg−1) either alone or in combination significantly altered mouse locomotor activity.

These results suggest that l‐NAME and flurbiprofen/indomethacin act synergistically in their antinociceptive action in the mouse. Combination therapy with l‐NAME and flurbiprofen and a similar NSAID may provide an alternative to the clinical control of pain in man.
Dependence of the metabolism of nitric oxide (NO) in healthy human whole blood on the oxygenation of its red cell haemoglobin
Authors: Wennmalm Å. , Benthin G. , Petersson A.‐S.
Published: July 2012

Plasma or whole venous or arterialized blood from healthy human donors was incubated with NO (50–300 μm), and the resulting formation of methaemoglobin (MetHb), nitrosyl haemoglobin (HbNO), and plasma nitrite and nitrate were measured. In plasma, NO was converted to nitrite and nitrate in a ratio of 5:1. In arterial blood (O2 sat. 94–99%) NO was almost quantitatively converted to nitrate and MetHb. No nitrite was detected and HbNO formation was low. In venous blood (O2 sat. 36–85%) more HbNO and less nitrate was formed, in comparison to arterialized blood. We propose that NO liberated from endothelium of conductance and resistance vessels is taken up by red blood cells and inactivated by HbO2 via stoichiometric conversion to MetHb and nitrate.
ATP mediates excitatory synaptic transmission in mammalian neurones
Authors: Silinsky E.M. , Gerzanich V. , Vanner S.M.
Published: July 2012

Adenosine 5′‐triphosphate (ATP, 0.1–100 μm), produced inward currents in patch‐clamped coeliac neurones from guinea‐pig when studied in either the whole cell configuration or in excised (outside‐out) patches. The P2‐purinoceptor antagonists suramin (80–230 μm) or reactive blue 2 (2–20 μm) depressed the ATP‐induced currents but not those produced by acetylcholine. Excitatory post‐synaptic currents (e.p.s.cs) were observed in cultured neurones. E.p.s.cs had similar current‐voltage relationships to currents evoked by ATP in excised patches and were reduced by suramin or reactive blue 2 to a similar extent as ATP currents. The results suggest that ATP is the excitatory neurotransmitter in cultures of these neurones.