Contractile effect of bombesin on guinea pig lung in vitro: involvement of gastrin-releasing peptide-preferring receptors

1993 ◽  
Vol 264 (1) ◽  
pp. L80-L86 ◽  
Author(s):  
E. Lach ◽  
E. B. Haddad ◽  
J. P. Gies
Keyword(s):  
Methyl Ester ◽  
Guinea Pig ◽  
Binding Studies ◽  
Gastrin Releasing Peptide ◽  
Peripheral Airways ◽  
Neuromedin B ◽  
Specific Antagonist ◽  
Acid Metabolites ◽  
The Right

Bombesin (Bn) and related agonists produce a potent contractile response in guinea pig peripheral airways in vitro, with the following relative potencies: bombesin > gastrin-releasing peptide (GRP) > neuromedin C ≫ neuromedin B. Specific GRP-preferring receptor antagonists, namely [D-Phe6]Bn-(6–13)methyl ester and [D-Phe6,Cpa14,psi 13–14]Bn(6–14)-NH2, inhibited bombesin-induced lung contraction with high potencies [negative logarithm of the molar concentration of antagonist that produces a twofold shift to the right in the agonist dose-response curve (pA2) of 7.1 and 7.2, respectively], whereas the less-specific antagonist [Leu14,psi 13–14]Bn has a lower one (pA2 of 5.6). In binding studies, the high affinities of GRP, [D-Phe6]Bn(6–13)methyl ester and [D-Phe6,Cpa14,psi 13–14]Bn(6–14)NH2 in contrast with the low affinity of neuromedin B agree with the hypothesis that GRP-preferring receptors are involved in bombesin-induced bronchoconstriction. Bombesin-induced bronchoconstriction is unaffected by atropine, hexamethonium, propranolol, triprolidine, methysergide, Ro 19–3704, and indomethacin or AA-861, suggesting that the Bn response does not occur via a mechanism involving the corresponding endogeneous agents or via the release of arachidonic acid metabolites. Moreover, the effect of Bn is insensitive to capsaicin pretreatment, excluding the involvement of endogeneous neuropeptides. Present results provide evidence that Bn-induced bronchoconstriction results from a direct effect of Bn on bronchial smooth muscle GRP-preferring receptors.

GRP-preferring bombesin receptors increase generation of inositol phosphates and tension in rat myometrium

1993 ◽  
Vol 265 (6) ◽  
pp. C1579-C1587 ◽  
Author(s):  
F. Amiot ◽  
D. Leiber ◽  
S. Marc ◽  
S. Harbon
Keyword(s):  
Methyl Ester ◽  
Inositol Phosphates ◽  
Regulatory Proteins ◽  
Single Class ◽  
Gastrin Releasing Peptide ◽  
Uterine Contractions ◽  
High Affinity ◽  
Neuromedin B ◽  
Guanine Nucleotide Regulatory Proteins ◽  
Relative Potencies

In the estrogen-treated rat myometrium, bombesin (Bn) and related agonists triggered contraction and the increased generation of inositol phosphates. The relative order of potencies was identical for both responses: Bn = gastrin releasing peptide (GRP) = litorin = neuromedin C >> neuromedin B. Two specific GRP-preferring receptor antagonists, namely [D-Phe6]Bn-(6-13) methyl ester and [Leu14,psi 13-14]Bn were inhibitory for both Bn-mediated tension and generation of inositol phosphates. [125I-Tyr4]Bn bound to myometrial membranes with high affinity (Kd = 104 pM) to a single class of sites in a saturable and reversible manner. The relative potencies for inhibiting binding were GRP = litorin = [Tyr4]Bn (Ki = 0.4 to 0.6 nM) >> neuromedin B (Ki = 10.3 nM). The high affinity displayed by [D-Phe6]Bn-(6-13) methyl ester (Ki = 2.8 nM) and [Leu14,psi 13-14]Bn (Ki = 35 nM) for competing for [Tyr4]Bn binding supported the involvement of a GRP-preferring Bn receptor. Guanine nucleotides decreased the binding of [125I-Tyr4]Bn and accelerated the rate of ligand dissociation, reflecting the coupling of receptors to guanine nucleotide regulatory proteins (G proteins). The results demonstrate that rat myometrium expresses functional GRP-preferring Bn receptors whose activation stimulates the phospholipase C pathway, pertussis toxin-insensitive event that contributes to Bn-mediated uterine contractions.

Effect of gastrin-releasing peptide (GRP) on guinea pig gallbladder contrction in vitro

1995 ◽  
Vol 30 (6) ◽  
pp. 764-767 ◽  
Author(s):  
Feng Liu ◽  
Satoru Naruse ◽  
Tsuyoshi Ozaki ◽  
Toshiyuki Sazi ◽  
Takaharu Kondo ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Gastrin Releasing Peptide

Calcitonin gene-related peptide as potential neurotransmitter in guinea pig right atrium

1986 ◽  
Vol 250 (4) ◽  
pp. H693-H698 ◽  
Author(s):  
A. Saito ◽  
S. Kimura ◽  
K. Goto
Keyword(s):  
Guinea Pig ◽  
Right Atrium ◽  
Sinus Node ◽  
Calcitonin Gene Related Peptide ◽  
Dependent Manner ◽  
Chronotropic Response ◽  
Related Peptide ◽  
Calcitonin Gene ◽  
The Right

The potential neurotransmitter role of calcitonin gene-related peptide (CGRP) in cardioacceleratory nonadrenergic noncholinergic (NANC) nerves was examined in the guinea pig right atrium in vitro. In the presence of atropine, a muscarinic antagonist, and atenolol, a beta-adrenoceptor antagonist, transmural nerve stimulation (TNS) of the isolated right atrium caused a positive chronotropic response, which is slow in both onset and decay. This TNS-induced slow response was assumed to be mediated by NANC nerves in the right atrium since tetrodotoxin inhibited the response. Dense distribution of CGRP-like immunoreactive (CGRP-I) nerves was demonstrated in the sinus node. Exogenously applied CGRP exerted a positive chronotropic effect on the isolated right atrium in a dose-dependent manner. Both CGRP-I nerves and NANC response induced by TNS were not affected by surgical sympathectomy and reserpine pretreatment but were abolished by the pretreatment of animals with capsaicin. The results suggest that CGRP is the neurotransmitter of cardioacceleratory NANC nerves in the right atrium of the guinea pig.

Influence of Acidosis on Cardiotonic Effects of Milrinone 

1998 ◽  
Vol 88 (3) ◽  
pp. 725-734 ◽  
Author(s):  
Makoto Tanaka ◽  
Tomohisa Ishikawa ◽  
Toshiaki Nishikawa ◽  
Katsutoshi Goto ◽  
Shigehito Sato
Keyword(s):  
Guinea Pig ◽  
Right Ventricular ◽  
Left Ventricular ◽  
Inotropic Effect ◽  
Control Group ◽  
Dependent Manner ◽  
Ph Values ◽  
The Right ◽  
Camp Formation

Background The present study was designed to determine whether augmentation of cardiac performance by milrinone is affected by acidosis in in vivo canine and in vitro guinea pig preparations, and to elucidate a mechanism in relation to the cyclic adenosine monophosphate (cAMP) formation. Methods Halothane-anesthetized, ventilated dogs were randomly assigned to a control group (arterial pH [pHa] approximately 7.4, base excess [BE] > -2 mM; n = 7), mild acidosis group (pHa approximately 7.2, BE < -9 mM; n = 7); or severe acidosis group (pHa < 7, BE < -20 mM; n = 6). Arterial blood pressure, left ventricular pressure (including maximum rate of increase, LV dP/dtmax), and pulmonary blood flow (PBF) were measured. Acidosis was induced by transient hypoxia and maintained with hydrogen chloride infusion. Hemodynamic responses to milrinone infusions at 2 and 5 microg x kg(-1) x min(-1) were then studied. In addition, left atria and right ventricular strips were dissected from guinea pig hearts and suspended in HEPES-Tyrode solution, with pH values adjusted to 7.4, 7, or 6.6. The concentration-response relation of isometric contractions for milrinone (10(-7) to 10(-4) M) and 8-bromo-cAMP (10(-4) to 10(-3) M) were determined. Results In the control group of dogs, significant increases in LV dP/dtmax (2,674 +/- 822 to 3,999 +/- 1,016 mmHg/s [means +/- SD]) and PBF (2.04 +/- 0.98 to 2.44 +/- 0.96 l/min [means +/- SD]) were seen with a milrinone infusion of 5 microg x kg(-1) x min(-1). In the mild acidosis group, 5 microg x kg(-1) x min(-1) milrinone also increased LV dP/dtmax and PBF. However, neither LV dP/dtmax nor PBF changed in the severe acidosis group. In in vitro experiments, milrinone exerted a positive inotropic effect in a concentration-dependent manner on the right ventricular preparations at pH 7.4, but not at pH 7 and 6.6, whereas no significant difference was observed in inotropic responses to 8-bromo-cAMP at pH values of 6.6, 7, and 7.4 on the right ventricular strips. In the right ventricular in vitro preparation, 10(-4) M milrinone was accompanied by a significant increase in intracellular cAMP content at apH of 7.4 but not 7. Conclusions These results indicate that the inotropic effect of milrinone is attenuated by acidosis due, at least in part, to decreased cAMP formation in acidotic muscle.

Anaphylaxis in guinea-pig peripheral airways in vitro

1979 ◽  
Vol 54 (1-2) ◽  
pp. 69-78 ◽  
Author(s):  
Howard W. Mitchell ◽  
Michael A. Denborough
Keyword(s):  
Guinea Pig ◽  
Peripheral Airways

scholarly journals Effect of the Versatile Bifunctional Chelator AAZTA5 on the Radiometal Labelling properties and the in vitro performance of a Gastrin Releasing Peptide Receptor Antagonist

2020 ◽  
Author(s):  
Michael Hofstetter ◽  
Euy Sung Moon ◽  
Fabio D'Angelo ◽  
Lucien Geissbühler ◽  
Ian Alberts ◽  
...  
Keyword(s):  
Great Promise ◽  
Binding Studies ◽  
Peptide Receptor ◽  
Gastrin Releasing Peptide ◽  
Indium 111 ◽  
Pc3 Cells ◽  
Gallium 68 ◽  
Therapy Studies

Abstract Background: Gastrin Releasing Peptide receptor (GRPr)-based radioligands have shown great promise for diagnostic imaging of GRPr-positive cancers, such as prostate and breast.The present study aims at developing and evaluating a versatile GRPr-based probe for both PET/SPECT imaging as well as intraoperative and therapeutic applications. The influence of the versatile chelator AAZTA5 on the radiometal labelling properties and the in vitro performance of the generated radiotracers were thoroughly investigated.The GRPr-based antagonist D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 was functionalized with the chelator 6-[Bis(carboxymethyl)amino]-1,4-bis(carboyxmethyl)-6-methyl-1,4-diazepane (AAZTA5) through the spacer 4-amino-1-carboxymethyl-piperidine (Pip) to obtain AAZTA5-Pip-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 (LF1). LF1 was radiolabelled with gallium-68 (PET), indium-111 (SPECT, intraoperative applications) and lutetium-177 (therapy, SPECT). In vitro evaluation included stability studies, determination of lipophilicity, protein-binding studies, determination of Kd and Bmax as well as internalization studies using the epithelial human prostate cancer cell line PC3. In vitro monotherapy as well as combination therapy studies were further performed to assess its applicability as a theranostic compound.Results: LF1 was labelled with gallium-68, indium-111 and lutetium-177 within 5 min at room temperature (RT). The apparent molar activities (Am) were ranging between 50-60 GBq/µmol for the 68Ga-labelled LF1, 10-20 GBq/µmol for the 111In- and 177Lu-labelled LF1. The radiotracers were stable for a period of 4 h post labeling exhibiting a hydrophilic profile with an average of a LogDoctanol/PBS of -3, while the bound activity to the human serum protein was approximately 10%. 68/natGa-LF1, 177/natLu-LF1 and 111/natIn-LF1 exhibited high affinity for the PC3 cells, with Kd values of 16.3±2.4 nM, 10.3±2.73 nM and 5.2±1.9 nM, respectively, and the required concentration of the radiotracers to saturate the receptors (Bmax) was between 0.5 and 0.8 nM which corresponds to approximately 4 x 105 receptors per cell. Low specific internalization rate was found in cell culture, while the total specific cell surface bound uptake always exceeded the internalized activity. In vitro therapy studies showed that inhibition of PC3 cells growth is somewhat more efficient when combination of 177Lu-labelled LF1 with rapamycin is applied compared to 177Lu-laballed LF1 alone.Conclusion: Encouraged by these promising in vitro data, preclinical evaluation of the LF1 precursor are planned in tumour models in vivo.

scholarly journals Nerve Fibres Containing Gastrin-Releasing Peptide around Pial Vessels

1983 ◽  
Vol 3 (3) ◽  
pp. 386-390 ◽  
Author(s):  
Rolf Uddman ◽  
Lars Edvinsson ◽  
Christer Owman ◽  
Frank Sundler
Keyword(s):  
Spinal Cord ◽  
Guinea Pig ◽  
Cord Blood ◽  
Choroid Plexus ◽  
Blood Vessels ◽  
Nerve Fibres ◽  
Pial Arteries ◽  
Gastrin Releasing Peptide ◽  
Pial Vessels

Nerve fibres containing immunoreactive gastrin-releasing peptide (GRP) were demonstrated around pial blood vessels of cat, guinea pig, rat, and mouse. A sparse supply was found around spinal cord blood vessels, whereas the choroid plexus seemed to be devoid of GRP fibres. Sympathectomy did not affect the number or distribution of the GRP fibres. The administration of neither GRP nor its closely related analogue, bombesin, contracted or dilated feline pial arteries in vitro.

scholarly journals Effect of the Versatile Bifunctional Chelator AAZTA5 on the Radiometal Labelling properties and the in vitro performance of a Gastrin Releasing Peptide Receptor Antagonist

2020 ◽  
Author(s):  
Michael Hofstetter ◽  
Euy Sung Moon ◽  
Fabio D'Angelo ◽  
Lucien Geissbühler ◽  
Ian Alberts ◽  
...  
Keyword(s):  
Great Promise ◽  
Specific Cell ◽  
Binding Studies ◽  
Peptide Receptor ◽  
Gastrin Releasing Peptide ◽  
Pc3 Cells ◽  
Therapy Studies

Abstract Background: Gastrin Releasing Peptide receptor (GRPr)-based radioligands, mainly antagonists, have shown great promise for diagnostic imaging of GRPr-positive cancers, such as prostate and breast.The present study aims at developing and evaluating a versatile GRPr-based probe for both PET / SPECT imaging as well as intraoperative and therapeutic applications. The influence of the versatile chelator AAZTA5 on the radiometal labelling properties and the in vitro performance of the generated radiotracers were thoroughly investigated.The GRPr-based antagonist D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 was functionalized with the chelator 6-[Bis(carboxymethyl)amino]-1,4-bis(carboyxmethyl)-6-methyl-1,4-diazepane (AAZTA5) through the spacer 4-amino-1-carboxymethyl-piperidine (Pip) to obtain AAZTA5-Pip-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 (LF1). LF1 was radiolabelled with 68Ga (PET), 111In (SPECT, intraoperative applications) and 177Lu (therapy, SPECT). In vitro evaluation included stability studies, determination of lipophilicity, protein-binding studies, determination of Kd and Bmax as well as internalization studies using the epithelial human prostate cancer cell line PC3. In vitro monotherapy as well as combination therapy studies were further performed to assess its applicability as a theranostic compound.Results: LF1 was labelled with 68Ga, 111In and 177Lu within 5 min at room temperature (RT). The molar activities (Am) were ranging between 50-60 MBq/nmol for 68Ga-LF1, 10-20 MBq/nmol for 111In-LF1 and 177Lu-LF1. The radiotracers were found to be stable for a period of 4 h post labeling exhibiting a hydrophilic profile with an average of a LogDoctanol/PBS of -3, while the bound activity to the human serum protein was approximately 10%. 68/natGa-LF1, 177/natLu-LF1 and 111/natIn-LF1 exhibited high affinity for the PC3 cells, with Kd values of 16.27±2.45 nM, 10.25±2.73 nM and 5.16±1.94 nM, respectively, and the required concentration of the radiotracers to saturate the receptors (Bmax) was between 0.5 and 0.8 nM which corresponds to approximately 4 x 105 receptors per cell. Low specific internalization rate was found in cell culture, while the total specific cell surface bound uptake always exceeded the internalized activity. In vitro therapy studies showed that combination of 177Lu-LF1 with rapamycin inhibit the growth of PC3 cells more efficiently compared to 177Lu-LF1 alone.Conclusion: Encouraged by these promising in vitro data, preclinical evaluation of the LF1 precursor are planned in tumour models in vivo.

In vitro studies on cetamolol, a new potent cardioselective β-adrenoceptor blocking agent with intrinsic sympathomimetic activity

1983 ◽  
Vol 61 (10) ◽  
pp. 1109-1115 ◽  
Author(s):  
D. Grimes ◽  
M. Stern ◽  
A. Wojdan ◽  
J. R. Cummings
Keyword(s):  
Guinea Pig ◽  
Blocking Agent ◽  
In Vitro Studies ◽  
Intrinsic Sympathomimetic Activity ◽  
Moderate Degree ◽  
Binding Studies ◽  
Adrenoceptor Antagonist ◽  
Potent Antagonist ◽  
Adrenergic Blocking

In vitro studies on the new β-adrenoceptor antagonist, cetamolol (Betacor®), have demonstrated that the compound is a potent antagonist of the chronotropic effects of isoproterenol on guinea pig atria. The pA2 value (8.05) of cetamolol was slightly lower than that of propranolol (8.44). The compound was shown to possess a moderate degree of cardioselectivity as indicated by a lower pA2 value for the antagonism of isoproterenol-induced relaxation of the isolated guinea pig trachea (pA2 = 7.67) compared with that derived from atrial experiments (pA2 = 8.05). Up to concentrations of 10−4 M, cetamolol displayed negligible negative inotropic activity relative to propranolol in the electrically stimulated guinea pig left atrial preparation. When applied to isolated right atria from reserpinized rats, cetamolol had a positive chronotropic effect (approximately 75% of that displayed by practolol) which was antagonized by pretreatment with propranolol, thus indicating intrinsic sympathomimetic activity. Specificity experiments in a number of isolated tissues indicated that cetamolol had very little antihistaminic, anticholinergic, α1-adrenergic blocking, or calcium antagonistic properties. Biochemical receptor binding studies are in general agreement with the observations from the isolated tissue experiments.

Evaluation of 99mTc-Label led Vitamin K4 as an Agent for Testicular Imaging

1991 ◽  
Vol 30 (01) ◽  
pp. 35-39 ◽  
Author(s):  
H. S. Durak ◽  
M. Kitapgi ◽  
B. E. Caner ◽  
R. Senekowitsch ◽  
M. T. Ercan
Keyword(s):  
Soft Tissue ◽  
Room Temperature ◽  
Normal Subjects ◽  
Left Testis ◽  
Wide Range ◽  
Activity Ratios ◽  
The Right ◽  
Radioactivity Levels

Vitamin K4 was labelled with 99mTc with an efficiency higher than 97%. The compound was stable up to 24 h at room temperature, and its biodistribution in NMRI mice indicated its in vivo stability. Blood radioactivity levels were high over a wide range. 10% of the injected activity remained in blood after 24 h. Excretion was mostly via kidneys. Only the liver and kidneys concentrated appreciable amounts of radioactivity. Testis/soft tissue ratios were 1.4 and 1.57 at 6 and 24 h, respectively. Testis/blood ratios were lower than 1. In vitro studies with mouse blood indicated that 33.9 ±9.6% of the radioactivity was associated with RBCs; it was washed out almost completely with saline. Protein binding was 28.7 ±6.3% as determined by TCA precipitation. Blood clearance of 99mTc-l<4 in normal subjects showed a slow decrease of radioactivity, reaching a plateau after 16 h at 20% of the injected activity. In scintigraphic images in men the testes could be well visualized. The right/left testis ratio was 1.08 ±0.13. Testis/soft tissue and testis/blood activity ratios were highest at 3 h. These ratios were higher than those obtained with pertechnetate at 20 min post injection.99mTc-l<4 appears to be a promising radiopharmaceutical for the scintigraphic visualization of testes.

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