Molecular Human Reproduction, Vol. 9, No. 8, 475-480,
August 2003
© 2003 European Society of Human Reproduction and Embryology
Article |
Investigation of the role of the serotonergic activity of certain subtype-selective 
1A antagonists in the relaxant effect on the pregnant rat uterus in vitro
Submitted on March 13, 2003; accepted on April 23, 2003
University of Szeged, Faculty of Pharmacy, Department of Pharmacodynamics and Biopharmacy, H-6720 Szeged, Eötvös u. 6, Hungary
1 To whom correspondence should be addressed. e-mail: falkay{at}pharma.szote.u-szeged.hu
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ABSTRACT |
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Results from recent studies have shown that
1A-adrenergic receptor (1A-AR) antagonists could offer a new alternative in the treatment of preterm delivery. However, members of this group [2-(2,6-dimethoxyphenoxyethyl)aminomethyl-1,4-benzodioxane hydrochloride (WB4101), 5-methylurapidil (5-MU)] are known to influence serotonin (5-hydroxy-tryptamine) (5-HT1A) receptors, too. Our objective was to clarify the role of their 5-HT1A activities in the uterus relaxant effect. RT–PCR was used to determine mRNA expression of the receptor subtypes in 22 day pregnant rat uteri. Isolated uteri were stimulated by 5-HT or electrical field to investigate the contraction-inhibiting effect and the 5-HT1A activity of the 1A antagonists. Both receptor subtypes are present in rat myometrium. 5-HT induced contractions were inhibited by the 1A antagonists. Besides shifting the dose–response curve of 5-HT to the right, 5-MU decreased its maximal effect. The 1A antagonists inhibited electrical field stimulation-induced contractions. 5-HT1A blockade increased the maximal effect of 5-MU but did not change that of WB4101. These results suggest that the contraction increase caused by 5-HT is mediated by 1A receptors. Serotonergic activity of 1 antagonists and especially 1A antagonists should be investigated as it may alter their efficacy and could interfere with their side-effects. It is proposed that novel 1A antagonists should be designed with no 5-HT1A activity to achieve maximal relaxant effect. Key words: alpha1A-adrenoceptors/5-HT1A receptors/rat/tocolysis/uterus
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Introduction |
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It has been clearly established that the adrenergic system plays a major role in the regulation of myometrial contractility during pregnancy (Marshall, 1981; Legrand and Maltier, 1986). Thus, a number of attempts have been made to employ drugs that affect the adrenergic system in the treatment of myometrial contractility disorders, with special attention to premature labour. Currently, ß2-adrenergic-receptor (ß2-AR) agonists are among the substances most frequently used as tocolytics; however, controversy surrounds their efficacy, especially when they are administered in prolonged therapies (Lampert et al., 1993; Katz and Farmer, 1999; Rosenberg, 2001). In the rat, besides the ß2-ARs, the
1-adrenergic receptors (1-ARs) have been found to have a great impact on myometrial contractility (Legrand and Maltier, 1986; Zupkó et al., 1997). This gave the initiative for a series of new investigations exploring the possible scientific and therapeutic significance of these adrenergic receptors.
In the pregnant rat, the 1/ß2-AR density ratio increases towards the end of pregnancy, this increase is mainly a consequence of an elevated 1-AR density and not a decrease in ß2-AR density (Gáspár et al., 2001). Further studies have revealed that, of the three subtypes of 1-ARs, it is the 1A subtype that is mostly responsible for the increase (Ducza et al., 2002). It has also been reported that blockade of 1A-ARs significantly inhibits contractions of post-partum rat myometrium in vitro (Ducza et al., 2001). Subsequent investigations showed that 1A-AR antagonists significantly increase the efficacy of the ß2-AR agonists, by raising their maximal contraction-inhibiting effect and markedly decreasing their EC50 (Mihalyi et al., 2003).
The investigated 1-AR blockers, 2-(2,6-dimethoxyphenoxyethyl)aminomethyl-1,4-benzodioxane hydrochloride (WB 4101) and 5-methylurapidil (5-MU) are known to have serotonergic properties too. These substances bind to serotonin1A (5-HT1A) receptors and exert an agonist effect on them (Schoeffter and Hoyer, 1988; Eltze et al., 1991; Moser, 1991; Chidlow et al., 2001).
Data have previously been published on the interactions between 5-HT1A-receptor agonists and 1-AR subtypes (Castillo et al., 1993). The aim of the present study was therefore to clarify whether the serotonergic activities of these subtype-selective 1-AR antagonists have any influence on their uterus-relaxant effect.
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Materials and methods |
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All parts of the study involving animal subjects were conducted with the approval of the Ethical Committee of Animal Experiments of the University of Szeged (registration number: 1-74-8/2002).
Mating of the animals
Mature female (180–200 g) and male (240–260 g) Sprague–Dawley (SPRD) rats were mated in a special mating cage. A metal door, movable by a small electric engine, separated the rooms for the male and female animals. A timer controlled the function of the engine. Since rats are usually active at night, the separating door was opened before dawn. Within 4–5 h after the possible mating, vaginal smears were taken from the female rats, and a sperm search was performed under a microscope at a magnification of 1200 times. If the search proved positive, or when smear taking was impossible because of an existing vaginal sperm plug, the female rats were separated and were regarded as first-day pregnant animals.
Reverse-transcription polymerase chain reaction (RT–PCR) studies
RT–PCR was utilized to determine mRNA expression of the 5-HT1A receptors and the 1A-ARs.
Tissue isolation
Female SPRD rats (250–300 g) were killed by cervical dislocation on day 22 of gestation (end-term). Uterus tissue was rapidly removed. Two myometrial rings from both horns of the uterus were sliced out and prepared for isolated tissue experiments. The remainder was dissected in ice-cold saline (0.9% NaCl) containing 2 U/ml of recombinant ribonuclease inhibitor (RNasin, Promega, UK). The samples were frozen in liquid nitrogen and then stored at –70°C until total RNA extraction.
Total RNA preparation
Total cellular RNA was isolated by extraction with guanidinium thiocyanate-acid–phenol–chloroform, according to the procedure of Chomczynski and Sacchi (Chomczynski and Sacchi, 1987). After precipitation with isopropanol, the RNA was treated with RNase-free DNase I for 30 min at 37°C, re-extracted with phenol, precipitated with ethanol, washed with 75% ethanol and then resuspended in diethyl pyrocarbonate-treated water. The RNA concentration was determined by optical density measurements at 260 nm.
RT–PCR
RNA (0.5 µg) was denaturated at 70°C for 5 min in a reaction mixture containing 20 U of RNase inhibitor (Hybaid, UK), 200 µmol/l dNTP (Sigma-Aldrich, Hungary), 20 µmol/l oligo(dT) (Hybaid, UK) in 50 mmol/l Tris–HCl, pH 8.3, 75 mmol/l KCl and 5 mmol/l MgCl2 in a final reaction volume of 19 µl. After the mixture had been cooled to 4°C, 20 U of M-MLV reverse transcriptase, RNase H Minus (Promega, UK) was added, and the mixture was incubated at 37°C for 60 min and then at 72°C for 10 min.
The PCR was carried out with 5 µl of cDNA, 25 µl of ReadyMix REDTaq PCR reaction mix (Sigma-Aldrich, Hungary) and 50 pmol/l sense and antisense primer. The primer sequences to amplify the 5-HT1A(-receptor mRNA) were 5'-CCA AAG AGC ACC TTC CTC TG-3' (for the forward primer) and 5'-TAC CAC CAC CAT CAT CAT CA-3' (for the reverse primer); these primers were anticipated to generate a 388 bp PCR product (Albert et al., 1989). The primers for the 1A-AR were 5'-GTA GCC AAG AGA GAA AGC CG-3' and 5'-CAA CCC ACC ACG ATG CCC AG-3'; these primers generated a 212 bp PCR product (Scofield et al., 1995). A rat GAPDH probe was used as internal control in all samples (Tso et al., 1985)]. The PCR was performed with a PCR Sprint thermal cycler (Hybaid Corp., UK), with the following cycle parameters: after initial denaturation at 95°C for 3 min, the reactions were taken through 35 cycles of 1 min at 95°C, 1 min annealing at 55°C, and 1 min at 72°C. After the last cycle, incubation was continued for 3 min at 72°C, followed by lowering of the temperature to 4°C. PCR products were used immediately or stored at –70°C. The PCR products were visualized by performing the electrophoresis on ethidium bromide (Sigma-Aldrich, Hungary) containing gel. Densitometric scanning of the gel was performed with the KODAK EDAS290 system (Csertex Ltd, Hungary). The 5-HT1A/GAPDH amplification ratio was calculated for each RNA pool. The 1A-AR/GAPDH ratio was also calculated for each RNA pool.
Isolated tissue studies
Preparation of the tissues
Uterus rings were taken from the above-mentioned 22 day pregnant SPRD rats. Two muscle rings were sliced from both horns of the uterus and mounted vertically between two platinum electrodes in a tissue bath containing 10 ml of de Jongh buffer solution (composition in mmol/l: NaCl, 137; KCl, 3; CaCl2, 1; MgCl2, 1; NaHCO3, 12; NaH2PO4, 4; glucose, 6; pH 7.41). The temperature of the tissue bath was set to and maintained at 37°C, and carbogen (95% O2 + 5% CO2) was perfused continuously through the bath. Tissue samples were equilibrated under these conditions for 90 min before the experiments were started. The initial tension of the uterus rings was set to 1.5 g, which dropped spontaneously to 0.5 g by the end of the equilibration period.
Determination of contractility changes (5-HT stimulation).
Noncumulative concentration–response curves were constructed for 5-HT (Sigma-Aldrich, St Louis, MO, USA). The spontaneous contractions of the tissues were recorded for 4 min.
5-HT was then administered to the bath and the contractions were recorded for another 4 min. This procedure was repeated after a 5 min regeneration period during which the tissue samples were washed four times with de Jongh buffer solution. The 5-HT concentration range was 1x10–9–3x10–6 mol/l. Spontaneous contractions were regarded as the control. The contraction increase caused by 5-HT was expressed as a percentage of the control contractions.
In the following step noncumulative concentration–response curves were constructed for 5-HT, but this time in the presence of the subtype-selective 1A-AR antagonists, WB4101 (Tocris-Cookson, Bristol, UK) (Morrow and Creese, 1986; Hieble et al., 1995) and 5-MU (Sigma-Aldrich, USA) (Gross et al., 1988; 1990; Valenta et al., 1990) at both 1x10–7 and 1x10–6 mol/l. The procedure was similar to that described above, except recording of the control contractions was preceded by a 5 min incubation with the 1A-AR antagonists. Each concentration–response curve was constructed by using newly removed uterus samples. The reason for this was that, following a 30 min regeneration period after the first series of 5-HT stimulation, the changes in the contractions caused by the same concentrations of 5-HT were different as the basal contractions were smaller than in the first series.
The tensions of the myometrial rings were measured with a strain gauge transducer (SG-02; Experimetria Ltd, London, UK) and recorded with an Isosys Data Acquisition System (Experimetria Ltd).
Electrical field stimulation (EFS)
Noncumulative concentration–response curves were constructed for the 1A-AR antagonists, WB4101 and 5-MU. Contractions were elicited by a digital programmable stimulator (ST-02; Experimetria Ltd), using square pulses with a duration of 150 ms and a frequency of 23.75 s. The stimulating potential in each experiment was 40 V. After the previously described equilibration period, the tissue samples were stimulated by EFS for 4 min and the contractions were recorded and regarded as the control. The 1A-AR antagonists were then added to the bath and the contractions were recorded for another 4 min. This procedure was repeated after a 5 min regeneration period, during which the tissues were washed four times. Following this, noncumulative concentration–response curves were constructed for the 1A-AR antagonists in the presence of 1x10–7 and 5x10–7 M (S)-N-tert-butyl-3-(4-(2-methoxyphenyl)-piperazin-1-yl)-2-phenylpropanamide (WAY100135) (Fletcher et al., 1993a; 1993b), a subtype-selective 5-HT1A-receptor antagonist. The experimental design was similar to the previous one, but the control phase was followed by a 5 min incubation period with WAY100135. Here, and also in the previous case when 5-HT was used to elicit contractions, newly removed uterus rings were used for each concentration–response curve.
Data analysis
The areas under the curves (AUCs) were analysed statistically with Prism 2.01 software (GraphPad Software, San Diego, CA, USA), using ANOVA with the Neuman–Keuls’ post hoc test. Data are given as the mean ± SEM and in all experiments n = 10.
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Results |
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Receptor mRNA expression
We demonstrated the expression of
1A-AR mRNA and 5-HT1A-receptor mRNA on day 22 of pregnancy in the rat by RT–PCR. Both receptor subtypes are present in pregnant rat myometrium (Figure 1).
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Effects of
1A-AR antagonists on 5-HT-induced contractions5-HT increased the contractions of pregnant rat myometrium in a concentration- dependent manner (Figure 2). The EC50 and the maximal effect of 5-HT are presented in the first row of Table I. WB4101 (1x10–7 mol/l) shifted the concentration–response curve of 5-HT to the right (Figure 2), significantly increasing its EC50, but not markedly altering its maximal effect (Table I, row 2). When WB4101 was present at 1x10–6 mol/l the right-shift of the concentration–response curve of 5-HT was more explicit (Figure 2) and its EC50 increased further, but the maximal effect was not altered (Table I, row 3).
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Similar phenomena were observed when the concentration–response curve of 5-HT was constructed in the presence of 5-MU (1x10–7 mol/l). The
1A-AR antagonist shifted the curve to the right (Figure 3) and, as in the previous case, the EC50 of 5-HT was significantly elevated whilst there was no significant change on the maximal effect (Table I, row 4).
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Interestingly, when 5-MU was applied at 1x10–6 mol/l concentration the dose–response curve of 5-HT was again shifted to the right (Figure 3), but the increase in the EC50 was accompanied by a significant decrease in the maximal effect of 5-HT (Table I, row 5).
Changes in contractility caused by 1A-AR blockade and simultaneous 5-HT1A-receptor blockade
WB4101 inhibited EFS-elicited contractions in a concentration-dependent manner (Figure 4). The EC50 and the maximal contraction-inhibiting effect are presented in the first row of Table II.
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5-HT1A-receptor blockade with WAY100135 (1x10–7 mol/l) did not change the contraction-inhibiting features of WB 4101. The 5-HT1A-receptor antagonist had no effect on the shape or the position of the concentration–response curve of WB4101 (Figure 4). No significant change was observed regarding the EC50 or the maximal contraction-inhibiting effect of WB4101 (Table II, row 2). Raising the concentration of the 5-HT1A-receptor antagonist to 5x10–7 mol/l did not significantly alter the dose–response curve of WB4101 either (Figure 4). The EC50 and the maximal contraction-inhibiting effect of the
1A-AR antagonist remained unchanged (Table II, row 3).
The other subtype-selective 1A-AR antagonist, 5-MU, also proved to inhibit the EFS- induced contractions of the isolated rat myometrium in a dose-dependent way (Figure 5). The EC50 and maximal inhibitory effect are given in the fourth row of Table II. In the presence of WAY100135 (1x10–7 mol/l) the concentration–response curve of 5-MU was shifted slightly to the right (Figure 5), but no essential change was observed in the EC50. The maximal contraction-inhibiting effect of 5-MU showed an increase in the presence of WAY100135 (1 x 10–7 mol/l), but statistically this change did not prove to be significant (Table II, row 5). When the 5-HT1A-receptor antagonist was applied at 5x10–7 mol/l concentration the concentration–response curve of 5-MU was shifted further to the right (Figure 5). The EC50 of 5-MU did not display a considerable deviation in this case either, but the maximal contraction-inhibiting effect of the 1A-AR antagonist increased to a greater degree, and this increase was statistically significant (Table II, row 6).
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Discussion |
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Recent studies have shown that the subtype-selective
1A-AR antagonists have a pronounced relaxant effect on the pregnant rat uterus (Ducza et al., 2002) and they appreciably potentiate the effects of ß2-AR agonists (Mihalyi et al., 2003). These promising results may afford an adequate basis for a new approach in the treatment of preterm delivery, which is still a leading cause of perinatal morbidity and mortality, costing approximately 13 million lives annually (Althabe et al., 1999).
The existence of a close relationship between the serotonergic and adrenergic systems has been supported by a number of studies (Castillo et al., 1993). However, the data available concerning this relationship regarding the myometrium are limited, and the information relating to the different receptor subtypes involved in the relationship between the two systems is incomplete. With regard to the severity of the problem of preterm labour and the possible benefits of the use of subtype-selective 1-AR antagonists, it seemed to be particularly important to elucidate the role of the serotonergic features of these substances.
5-HT itself increased the contractility of the pregnant rat myometrium. Both 1A-AR antagonists inhibited the contraction-increasing effect of 5-HT. When 5-HT was administered in the presence of 1x10–7 mol/l WB4101, its concentration–response curve was shifted to the right, and when the concentration of WB4101 was increased by one magnitude the shift was even greater. In parallel with this, the maximal effect of 5-HT did not change significantly. These results suggest that there is a competitive antagonism between 5-HT and WB4101. Furthermore, since WB4101 binds to 1A-ARs with greater affinity than to 5-HT1A receptors, these results suggest that the contractility-increasing effect of 5-HT in the rat myometrium is (at least partially) mediated by 1A-ARs. Similarly, when the concentration–response curve of 5-HT was constructed in the presence of 1x10–7 mol/l 5-MU, the curve was moved to the right, and elevation of the concentration of 5-MU to 1x10–6 mol/l further increased this right-shift. However, when 5-HT was applied together with 5-MU, the coadministration led not only to a right-shift of the curve but also to a decrease in the maximal effect of 5-HT. These observations suggest that the serotonergic activities of the two 1A-AR antagonists differ substantially. To determine the difference between the substances in this respect, the dose–response curves of the 1A-AR antagonists were constructed alone and in the presence of the subtype-selective 5-HT1A-receptor antagonist WAY100135, EFS being used to elicit contractions. The contraction-inhibiting characteristics of WB4101 were not changed when the 5-HT1A-receptor antagonist at 1x10–7 mol/l was added. When a five times larger concentration of WAY100135, 5x10–7 mol/l, was applied, it did not alter the uterus-relaxant effect either. This again indicates that WB4101 inhibits contractions of the pregnant rat myometrium through 1A-ARs. Since WB4101 inhibited the 5-HT-induced contractions, these results strengthen the hypothesis that 5-HT-elicited contractions may also be mediated by 1A-ARs in the rat myometrium.
In contrast, the contraction-inhibiting properties of 5-MU changed when it was applied together with the 5-HT1A-receptor antagonist. Even in the presence of 1x10–7 mol/l WAY100135, 5-MU exhibited an increased maximal contraction-inhibiting effect. Elevation of the concentration of the 5-HT1A-receptor antagonist to 5x10–7 mol/l resulted in an even greater increase in the maximal effect of 5-MU, this increase proving to be statistically significant.
Impeding the serotonin agonist effect of 5-MU by 5-HT1A-receptor blockade raised the maximal contraction-inhibiting effect of 5-MU to 89.6 ± 5.4%, which is even higher than the maximal effect of WB4101, 76.5 ± 6.4%. These results suggest that the serotonergic activity of 5-MU is more pronounced than that of WB4101. The different chemical structures may offer an explanation for the noteworthy difference between the serotonergic properties of the two 1A-AR antagonists. It seems probable that 5-MU has a dual influence on the pregnant rat myometrium: a dominant 1A-AR antagonist effect that inhibits contractions, and a less expressed agonist effect on the 5-HT1A receptors that increases the contractility of the pregnant rat uterus.
Although subtype-selective 1A-AR antagonists are not yet used in pharmacotherapeutic practice, the data obtained on these substances so far suggests that they could improve the armamentarium of tocolytic agents. The results of the present study allow the assumption that in the future, subtype-selective 1A-AR antagonists should be designed with no or only negligible 5-HT1A-agonist activity so as to provide a maximal contraction-inhibiting effect.
Since the demand for highly specific, subtype-selective substances is great not only in the field of obstetrics but in other areas as well, the serotonergic activities of 1 antagonists and especially the 1A antagonists should be investigated, as this may alter the efficacy of such substances and could interfere with their side-effects.
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REFERENCES |
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Albert, P.R., Zhou, Q.Y., Tol, H.H.M.V., Bunzow, J.R. and Civelli, O. (1989) Cloning, functional expression and mRNA tissue distribution of the rat 5-hydroxytryptamine1A receptor gene. J. Biol. Chem., 265, 5825–5832.
Althabe, F., Carroli, G., Lede, R., Belizan, J.M. and Althabe, O.H. (1999) Preterm delivery: detection of risks and preventive treatment. Rev. Panam. Salud. Publica, 5, 373–385.[Medline]
Castillo, C., Ibarra, M., Márquez, J.A., Villalobos-Molina, R. and Hong, E. (1993) Pharmacological evidence for interactions between 5-HT1A-receptor agonists and subtypes of 1-adrenoceptors on rabbit aorta. Eur. J. Pharmacol., 241, 141–148.[CrossRef][Web of Science][Medline]
Chidlow, G., Cupido, A., Melena, J. and Osborne, N.N. (2001) Flesinoxan, a 5-HT1A receptor agonist/alpha 1-adrenoceptor antagonist, lowers intraocular pressure in NZW rabbits. Curr. Eye Res., 23, 144–153.[CrossRef][Web of Science][Medline]
Chomczynski, P. and Sacchi, N. (1987) Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. Anal. Biochem., 162, 156–159.[Web of Science][Medline]
Ducza, E., Gáspár, R., Márki, A., Gyula, P., Bottka, S. and Falkay, G. (2001) Use of antisense oligonucleotides to verify the role of the 1A-adrenergic receptor in the contractility of the rat uterus post partum. Mol. Pharmacol., 59, 1235–1242.
Ducza, E., Gáspár, R. and Falkay, G. (2002) Altered levels of mRNA expression and pharmacological reactivity of alpha-1A adrenergic receptor subtypes in the late-pregnant rat myometrium. Mol. Reprod. Dev., 62, 343–347.[CrossRef][Web of Science][Medline]
Eltze, M., Boer, R., Sanders, K.H. and Kolassa, N. (1991) Vasodilatation elicited by 5-HT1A receptor agonists in constant-pressure-perfused rat kidney is mediated by blockade of alpha 1A-adrenoceptors. Eur. J. Pharmacol., 202, 33–44.[CrossRef][Web of Science][Medline]
Fletcher, A., Bill, D.J., Bill, S.J., Cliffe, I.A., Dover, G.M., Forster, E.A., Haskins, J.T., Jones, D., Mansell, H.L. and Reilly, Y. (1993a) WAY 100135: a novel, selective antagonist at presynaptic and postsynaptic 5-HT1A receptors. Eur. J. Pharmacol., 237, 283–291.[CrossRef][Web of Science][Medline]
Fletcher, A., Cliffe, I.A. and Dourish, C.T. (1993b) Silent 5-HT1A antagonists: utility as research tools and therapeutic agents. Trends Pharmacol. Sci., 14, 41–48.[CrossRef][Medline]
Gáspár, R., Földesi, I., Havass, J., Márki, A. and Falkay, G. (2001) Characterization of late-pregnant rat uterine contraction via the contractility ratio in vitro. Significance of 1-adrenoceptors. Life Sci., 68, 1119–1129.[CrossRef][Web of Science][Medline]
Gross, G., Hanft, G. and Rugevics, C. (1988) 5-methylurapidil discriminates between subtypes of alpha1-adrenoceptor. Eur. J. Pharmacol., 151, 333–335.[CrossRef][Web of Science][Medline]
Gross, G., Schuttler, K., Xin, X. and Hanft, G. (1990) Urapidil analogues are potent ligands of the 5-HT1A receptor. J. Cardiovasc. Pharmacol., 7, S8–S16.
Hieble, J.P., Bondinell, W. and Ruffolo, R.R. (1995) and ß-adrenoceptors: from the gene to the clinic. 1. Molecular biology and subclassification. J. Med. Chem., 38, 3415–3444.[CrossRef][Web of Science][Medline]
Katz, V.L. and Farmer R.M. (1999) Controversies in tocolytic therapy. Clin. Obstet. Gynecol., 42, 802–819.[CrossRef][Web of Science][Medline]
Lampert, M.B., Hibbard, J., Weinert, L., Briller, J., Lindheimer, M. and Lang, R.M. (1993) Peripartum heart failure associated with prolonged tocolytic therapy. Am. J. Obstet. Gynecol., 168, 493–495.[Web of Science][Medline]
Legrand, C. and Maltier, J.P. (1986) Evidence for a noradrenergic transmission in the control of parturition in the rat. J. Reprod. Fertil., 76, 415–424.
Marshall, J.M. (1981) Effects of ovarian steroids and pregnancy on adrenergic nerves of uterus and oviduct. Am. J. Physiol., 240, C165–C174.[Medline]
Mihályi, A., Gáspár, R., Csonka, D. and Falkay, G. (2003) Synergism between ß2-adrenoceptor agonists and subtype-selective 1A-adrenoceptor antagonists in the tocolytic effect on pregnant rat uterus in vitro. Clin. Exp. Pharmacol. Physiol., 30, 164–167.[CrossRef][Web of Science][Medline]
Morrow, A.L. and Creese, I. (1986) Characterisation of 1-adrenergic receptor subtypes in rat brain: a re-evaluation of 3H-WB 4101 and 3H-prazosin binding. Mol. Pharmacol., 29, 321–330.[Abstract]
Moser, P.C. (1991) The effect of putative 5-HT1A receptor antagonists on 8-OH-DPAT-induced hypothermia in rats and mice. Eur. J. Pharmacol., 193, 165–172.[CrossRef][Web of Science][Medline]
Rosenberg, P. (2001) Tocolysis, use of beta-sympathomimetics for threatening preterm delivery: a critical review. J. Gynecol. Obstet. Biol. Reprod., 30, 221–230.[Medline]
Schoeffter, P. and Hoyer, D. (1988) Centrally acting hypotensive agents with affinity for 5-HT1A binding sites inhibit forskolin-stimulated adenylate cyclase activity in calf hippocampus. Br. J. Pharmacol., 95, 975–985.[Web of Science][Medline]
Scofield, M.A., Liu, F., Abel, P.W. and Jeffries, W.B. (1995) Quantification of steady state expression of mRNA for alpha-1 adrenergic receptor subtypes using reverse transcription and competitive polymerase chain reaction. J. Pharm. Exp. Ther., 275, 1035–1042.
Tso, J., Sun, X., Kao, T., Reece, K. and Wu, R. (1985) Isolation of rat and human glycerinaldehyde-3-phosphate dehydrogenase cDNA: genomic complexity and molecular evolution of the gene. Nucleic Acids Res., 13, 2485–2502.
Valenta, B. and Singer, E.A. (1990) Hypotensive effects of 8-hydroxy-2-(di-n-propylamino)tetralin and 5-methylurapidil following stereotaxic microinjection into the ventral medulla of the rat. Br. J. Pharmacol., 99, 713–716.[Web of Science][Medline]
Zupkó, I., Gáspár, R., Kovács, L. and Falkay, G. (1997) Are -adrenergic antagonists potent tocolytics? In vivo experiments on postpartum rats. Life Sci., 61, 159–163.
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