Actions of procaterol (OPC-2009), a new beta2-adrenoceptor stimulant, on pulmonary resistance, contractions of the soleus muscle, and cardiovascular system of the anaesthetized cat

Asthma and COPD: A Focus on β-Agonists - Past, Present and Future

Asthma has been recognised as a respiratory disorder for millennia and the focus of targeted drug development for the last 120 years. Asthma is one of the most common chronic non-communicable diseases worldwide. Chronic obstructive pulmonary disease (COPD), a leading cause of morbidity and mortality worldwide, is caused by exposure to tobacco smoke and other noxious particles and exerts a substantial economic and social burden. This chapter reviews the development of the treatments of asthma and COPD particularly focussing on the β-agonists, from the isolation of adrenaline, through the development of generations of short- and long-acting β-agonists. It reviews asthma death epidemics, considers the intrinsic efficacy of clinical compounds, and charts the improvement in selectivity and duration of action that has led to our current medications. Important β2-agonist compounds no longer used are considered, including some with additional properties, and how the different pharmacological properties of current β2-agonists underpin their different places in treatment guidelines. Finally, it concludes with a look forward to future developments that could improve the β-agonists still further, including extending their availability to areas of the world with less readily accessible healthcare.

Structure-based drug discovery for combating influenza virus by targeting the PA-PB1 interaction

Influenza virus infections are serious public health concerns throughout the world. The development of compounds with novel mechanisms of action is urgently required due to the emergence of viruses with resistance to the currently-approved anti-influenza viral drugs. We performed in silico screening using a structure-based drug discovery algorithm called Nagasaki University Docking Engine (NUDE), which is optimised for a GPU-based supercomputer (DEstination for Gpu Intensive MAchine; DEGIMA), by targeting influenza viral PA protein. The compounds selected by NUDE were tested for anti-influenza virus activity using a cell-based assay. The most potent compound, designated as PA-49, is a medium-sized quinolinone derivative bearing a tetrazole moiety, and it inhibited the replication of influenza virus A/WSN/33 at a half maximal inhibitory concentration of 0.47 μM. PA-49 has the ability to bind PA and its anti-influenza activity was promising against various influenza strains, including a clinical isolate of A(H1N1)pdm09 and type B viruses. The docking simulation suggested that PA-49 interrupts the PA–PB1 interface where important amino acids are mostly conserved in the virus strains tested, suggesting the strain independent utility. Because our NUDE/DEGIMA system is rapid and efficient, it may help effective drug discovery against the influenza virus and other emerging viruses.

Association between Selective Beta-adrenergic Drugs and Blood Pressure Elevation: Data Mining of the Japanese Adverse Drug Event Report (JADER) Database

Selective beta-adrenergic drugs are used clinically to treat various diseases. Because of imperfect receptor selectivity, beta-adrenergic drugs cause some adverse drug events by stimulating other adrenergic receptors. To examine the association between selective beta-adrenergic drugs and blood pressure elevation, we reviewed the Japanese Adverse Drug Event Reports (JADERs) submitted to the Japan Pharmaceuticals and Medical Devices Agency. We used the Medical Dictionary for Regulatory Activities (MedDRA) Preferred Terms extracted from Standardized MedDRA queries for hypertension to identify events related to blood pressure elevation. Spontaneous adverse event reports from April 2004 through May 2015 in JADERs, a data mining algorithm, and the reporting odds ratio (ROR) were used for quantitative signal detection, and assessed by the case/non-case method. Safety signals are considered significant if the ROR estimates and lower bound of the 95% confidence interval (CI) exceed 1. A total of 2021 reports were included in this study. Among the nine drugs examined, significant signals were found, based on the 95%CI for salbutamol (ROR: 9.94, 95%CI: 3.09-31.93) and mirabegron (ROR: 7.52, 95%CI: 4.89-11.55). The results of this study indicate that some selective beta-adrenergic drugs are associated with blood pressure elevation. Considering the frequency of their indications, attention should be paid to their use in elderly patients to avoid adverse events.

Production of an Extremly Low Dose Procaterol HCl Preparation by Fluidized-Bed Coating Method: In Vitro and In Vivo Evaluation

A convenient and reliable method to prepare procaterol HCl oral dosage form at an extremely low dosage (25 microg/cap) is presented in this paper. Procaterol HCl was mixed with the film-forming agent hydroxypropyl methylcellulose in an aqueous solution, which was then spray-coated on sugar spheres (Nu-pareil PG 20/25) to produce procaterol HCl pellets. The IR spectra of coated and noncoated pellets indicated that procaterol HCl was coated on the sugar spheres successfully with a weight increment less than 1%. Most of the coated pellets were able to pass through an 18-mesh screen with no agglomeration. The average weights of coated pellets filled inside of capsules were monitored during the filling process. A simple liquid chromatographic method was developed and validated for the assay and uniformity test of procaterol HCl in different dosage forms. The results of assay and content uniformity test for both in-house product and a commercial product, i.e., Meptin-mini tablet, were satisfied. The data of f(2) function and ANOVA analysis for the dissolution profiles of both procaterol HCl products suggested that they are pharmaceutical equivalent. In an in vivo study (n = 24), a single dose of 75 microg procaterol HCl was administrated to each volunteer and the plasma concentration of procaterol was determined by a LC/MS/MS method, developed by the same authors. There were no significant differences (p > 0.05) in the data of AUC(0-->16 h), AUC(0-->infinity), C(max), and MRT for both preparations. It is confirmed that the pellets capsule produced in this study is bioequivalent with Meptin-mini tablet.

Synthesis and biodistribution of [11c]procaterol, a beta2-adrenoceptor agonist for positron emission tomography

The potent, subtype-selective radioligand (+/-)-erythro-5-(1-hydroxy-2-[11C]isopropyl-aminobutyl)-8-hydroxy-car bostyril ([11C]procaterol) was synthesized and evaluated for visualization of pulmonary beta2-adrenoceptors with positron emission tomography (PET). Procaterol was labelled by reductive alkylation of the desisopropyl precursor with [11C]acetone under the influence of NaCNBH3 and acetic acid. Synthesis and HPLC purification were performed in 34 min. Specific activities ranged from 26.5-39.3 TBq (about 700-1000 Ci)/mmol and the radiochemical yield was 2.4-8.6% (corrected for decay). Biodistribution studies were performed in male Wistar rats which were either untreated or predosed with (D,L)-propranolol hydrochloride (beta-adrenoceptor antagonist, 2.5 mg/kg), ICI 118551 (beta2-adrenoceptor antagonist, 0.15 mg/kg), CGP 20712A (beta1-adrenoceptor antagonist, 0.15 mg/kg) or isoprenaline (beta1-adrenoceptor agonist, 15 mg/kg). Specific binding was observed in lungs, spleen and red blood cells, tissues known to contain beta2-adrenoceptors. Pulmonary binding was blocked by propranolol, ICI 118551 and isoprenaline, but not by CGP 20712A. This binding pattern is consistent with the beta2 selectivity of the radioligand. The clearance of [11C]procaterol was biphasic, with a rapid distribution phase (t1/2 0.17 min) representing 90% of the injected dose followed by an elimination phase (t1/2 18.1 min). About 45% of the plasma radioactivity was unmetabolized procaterol at 15 min postinjection. In a dynamic PET-study, the lungs of untreated control rats could barely be detected and total/non-specific binding ratios rose to only 1.2 at 20 min postinjection. Although labelling and administration of (-) erythroprocaterol, the most active of 4 stereoisomers, may produce better results, [11C]procaterol seems unsuitable for beta-adrenoceptor imaging.

Beta-adrenoceptor subtypes in the ureteral smooth muscle of rats, rabbits and dogs

We investigated the beta-adrenoceptor subtypes mediating ureteral relaxation in rats, rabbits and dogs. The relaxing effects of beta-adrenoceptor agonists were evaluated on KCl-induced ureteral contractions. The rank order of potency of the catecholamines tested was isoprenaline > noradrenaline > adrenaline in rat ureter; isoprenaline > adrenaline > noradrenaline in rabbit ureter; only isoprenaline was effective in canine tissues. The beta1-adrenoceptor agonist, dobutamine, produced relaxation of rat ureter. The beta2-adrenoceptor agonist, procaterol, produced more significant relaxation of rabbit ureter than did dobutamine. CL-316243 [(R,R)-5-[2-[[2-(3-chlorophenyl)-2-hydroxyethylamino]propyl]-1,3-b enzodioxole-2,2-dicarboxylate] and CGP-12177A [(+/-)[4-[3[(1,1-dimethylethyl)amino]-2-hydroxypropoxy]-1,3-dihydro-2H-+ ++benzimidazol-2-one hydrochloride], beta3-adrenoceptor agonists, were more effective in relaxing canine ureter than were dobutamine and procaterol. Isoprenaline-induced relaxation was antagonized by a beta1-adrenoceptor antagonist, CGP-20712A [2-hydroxy-5(2-((2-hydroxy-3-(4-((1-methyl-4-trifluoromethyl)1H-imidazol e-2-yl)phenoxy)propyl)amino)ethoxy)-benzamide monomethane sulphonate], in rats and by a beta2-adrenoceptor antagonist, ICI-118,551 [(+/-)-1-[(2,3-dihydro-7-methyl- 1H-inden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol hydrochloride], in rabbits. The non-selective beta-adrenoceptor antagonist, bupranolol, antagonized isoprenaline-induced relaxation in all species tested. In conclusion, beta-adrenoceptor agonists may relax ureter by stimulating mainly beta1-adrenoceptors in rats, beta2-adrenoceptors in rabbits and mainly beta3-adrenoceptors in dogs.

Modulation of pacemaker activity in sheep cardiac Purkinje fibers by stimulation of beta-adrenoceptor subtypes

The electrophysiological effects mediated by beta 1- and beta 2-adrenoceptors in spontaneously active sheep cardiac Purkinje fibers were investigated using the non-selective agonist (-)-isoproterenol (IPN) and the selective agonists (-)-noradrenaline (beta 1) and procaterol (beta 2) in the absence and presence of the selective antagonists bisoprolol (beta 1) and ICI 118,551 (beta 2). IPN (0.01 mumol/l) increased the spontaneous rate by 54% and the slope of diastolic depolarization by 68% of the respective control values. Further, IPN increased the action potential duration at -20 mV (APD -20 mV) from 96 to 154 ms, reduced the APD-70 mV by 17% and the duration of the diastole by 39% and slightly hyperpolarized the maximum diastolic potential. These effects were partially inhibited by ICI 118,551 (0.03 mumol/l), diminished by bisoprolol (0.1 mumol/l) and almost completely blocked by the combination of both antagonists. Concentration response curves of IPN were influenced by the selective antagonists as follows: ICI 118,551 (0.03 mumol/l) shifted the curves to the right by 0.2-0.4 log units and increased the slope factor. Bisoprolol (0.1 mumol/l) induced a greater shift to the right by 1.1-1.5 log units. Combination of bisoprolol with ICI 118,551 shifted the curves to the right by 1.5-1.7 log units. Noradrenaline (0.3 mumol/l) elicited similar actions as IPN. Bisoprolol (0.1 mumol/l) shifted the concentration response curves of noradrenaline to the right by 1.1-1.9 log units. Actions of procaterol (0.1 mumol/l) were weak, attained only 15-35% of the maximal effects of IPN and could be blocked by ICI 118,551 (0.03 mumol/l). These results show that the increase of pacemaker activity induced by catecholamines in sheep cardiac Purkinje fibers is predominantly mediated by stimulation of beta 1-receptors. However, contribution of beta 2-receptor mediated effects could be demonstrated.

Selective and full beta 1-adrenoceptor agonist action of a catechol derivative of denopamine (T-0509) in the guinea-pig cardiac muscle and trachea: comparison with denopamine, xamoterol and isoprenaline

1. The pharmacological actions of T-0509, a 3-hydroxy derivative of denopamine, were studied in various guinea-pig tissues; these effects were compared with those of isoprenaline, denopamine and xamoterol. 2. The intrinsic activities of the positive inotropic actions of T-0509, denopamine and xamoterol compared with isoprenaline (= 100%) in the papillary muscle were 99%, 83% and 28%, respectively, while their relative potencies (EC50 agonist EC50 isoprenaline) were 0.23, 33 and 1.4, respectively. The intrinsic activities of T-0509, denopamine and xamoterol as positive chronotropic agents in the right atria were 98%, 69% and 48%, respectively, and their equipotent concentrations (isoprenaline = 1) were 0.24, 50 and 4, respectively. 3. The positive chronotropic actions of T-0509 and denopamine were antagonized by bisoprolol (3 x 10(-8) M), but not by ICI 118,551 (3 x 10(-8) M). 4. The intrinsic activity of T-0509 in histamine-contracted tracheae was similar to that of isoprenaline, but its equipotent concentration was 38; the effects of both agents were antagonized by ICI 118,551 (3 x 10(-8) M), but not by bisoprolol (3 x 10(-8) M). Denopamine and xamoterol did not show any agonist activity on guinea-pig trachea. 5. Denopamine and xamoterol antagonized the positive chronotropic (pA2, denopamine: 6.98, xamoterol: 7.75) and tracheal relaxant (pA2, denopamine: 5.39, xamoterol: 6.25) effects of isoprenaline. 6. Isoprenaline, T-0509 and denopamine, but not xamoterol, contracted the guinea-pig aorta in a decreasing order in the presence of propranolol (10(-6) M).7. Based on the above studies, T-0509 appears to be a highly selective betaI-adrenoceptor agonist with full agonist properties, while denopamine and xamoterol appear to be selective, but partial betaI-adrenoceptor agonists.

Pre- and post-junctional actions of procaterol, a beta 2-adrenoceptor stimulant, on dog tracheal tissue

1. The effects of procaterol, a beta 2-adrenoceptor agonist, on excitatory neuro-effector transmission in the dog trachea were investigated and the findings were compared to those seen with isoprenaline, with microelectrode, double sucrose gap and tension recording methods. 2. Procaterol (10(-10)-10(-9) M) and isoprenaline (10(-9) M) had no effect on the resting membrane potential or on the input resistance of the smooth muscle cells of dog trachea. However with increased concentrations (greater than 10(-8) M), these agents hyperpolarized the membrane and decreased the input resistance of the membrane. 3. Procaterol (10(-10)-10(-7) M) and isoprenaline (10(-9)-10(-7) M) dose-dependently reduced the amplitude of the twitch contractions evoked by field stimulation in the combined presence of indomethacin (10(-5) M) and guanethidine (10(-6) M). In parallel with actions on twitch contractions, procaterol (10(-10)-10(-7) M) and isoprenaline (10(-9)-10(-7) M) reduced the amplitude of the excitatory junction potentials (e.j.ps), evoked by single pulse field stimulation in the dog trachea. 4. Procaterol (10(-8) M) had no effect on the post-junctional response of smooth muscle cells to exogenous acetylcholine (ACh) (10(-7)-10(-6) M). 5. Pretreatment with ICI-118551, a beta 2-adrenoceptor blocking agent, reduced the inhibitory action of procaterol on the amplitude of twitch contractions evoked by field stimulations in the dog trachea. 6. These results indicate that procaterol in low concentrations has a prejunctional action inhibiting the excitatory neuro-effector transmission in addition to a postsynaptic action, presumably by suppressing transmitter release from the vagus nerve terminals through beta 2-adrenoceptors in the dog tracheal tissue. The pre- and post-junctional actions of procaterol explain its potent bronchodilator effects in clinical use.

Comparison between oral procaterol and salbutamol in patients with bronchial asthma

The efficacy of procaterol, a new beta 2-selective sympathomimetic drug, was compared with that of salbutamol and placebo in a double-dummy crossover study in 20 asthmatic patients. Procaterol (0.1 mg orally) was given twice daily and salbutamol (4 mg orally) 3-times a day. The study was made up of four consecutive 4-day treatment periods including two periods of plain placebo. A significant direct bronchodilating effect of both procaterol and salbutamol could be seen in PEF values, measured 4-times a day, compared with the effect of placebo (p less than 0.01 for both). Procaterol was slightly superior to salbutamol. The afternoon and evening PEF values during the procaterol period did not differ from the values during the placebo period. In symptom scores, there was significantly more tremor during the procaterol period than during the placebo period (p less than 0.01). Both procaterol and salbutamol produced more palpitation than placebo (p less than 0.05). The study shows that oral procaterol is a potent bronchodilator. The doses of procaterol and salbutamol were not equivalent. Procaterol with the dose used in the study was more potent. Despite this, the duration of the bronchodilator effect of procaterol on a twice daily dosage did not seem to be long enough in all patients.

Relaxing actions of procaterol, a beta 2-adrenoceptor stimulant, on smooth muscle cells of the dog trachea

1. The effects of procaterol, a beta 2-adrenoceptor agonist, on smooth muscle cells of the dog trachea were investigated by use of microelectrode and isometric tension recording methods, and by measurement of Ca transients as estimated from the fura-2 fluorescence, adenosine 3':5'-cyclic monophosphate (cyclic AMP) and breakdown of phosphatidylinositols. 2. Procaterol hyperpolarized the membrane and increased the ionic conductance (above 10 nM) in a dose-dependent manner. These actions were inhibited by propranolol. 3. Procaterol inhibited the mechanical responses evoked by acetylcholine (ACh), histamine or 5-hydroxytryptamine (5-HT), in the presence or absence of Ca2+ in the bath solution, but not that evoked by high concentrations of ACh (1 microM). The ID50 value of procaterol for the peak amplitude of the ACh-induced contraction (30 nM) was 0.3 nM. The equivalent values for the histamine-induced phasic and tonic responses (10 microM) were 0.15 and 0.01 nM), respectively. 4. Procaterol (over 1 nM) increased the amount of cyclic AMP in a dose-dependent manner which was blocked by prior application of propranolol. 5. Procaterol did not alter the changes in the amounts of phosphatidylinositol 4,5-bisphosphate (PI-P2) and phosphatidic acid (PA) induced by ACh, histamine or 5-HT. Thus, the synthesis of inositol 1,4,5-trisphosphate is not affected by stimulation of the beta 2-adrenoceptor. 6. ACh increased the free Ca2+ concentration to a greater extent than that produced by histamine or 5-HT. These changes were reduced by procaterol, except for those induced by high concentrations of ACh (over 1 microM). 7. It is concluded that procaterol relaxes tissues precontracted by various agonists due to a reduction in the free Ca2+. This inhibitory action may be due to an increase in the amount of cyclic AMP but does not result from an inhibition of the hydrolysis of phosphatidyl inositols. The hyperpolarization induced by procaterol may partly contribute to the observed relaxation.

Autoradiographic location of beta-adrenoceptor subtypes in cat colon smooth muscle

In order to localize beta-adrenoceptors 125I-(-)pindolol (IPIN) was used in binding to sections from cat colon. The binding characteristics for IPIN to beta-adrenoceptors on colon sections were estimated by demonstrating reversible binding in the presence of isoprenaline and by steroselective binding to the isomers of propranolol. The binding of IPIN to both beta 1- and beta 2-adrenoceptors was shown by biphasic displacement curves in the presence of the selective beta-adrenoceptor compounds betaxolol, ICI 118.551 and procaterol. The colon sections were found to contain proportions of beta 1-adrenoceptors (30-50%) and beta 2-adrenoceptors (50-70%). In the autoradiographic studies, 100% of the developed grains after exposure of IPIN to the photographic emulsion were displaced by 50 microM of isoprenaline. By microscopic counting at autoradiographic grains, 30-40% of the grains were found in the circular smooth muscle, while 60-70% of the grains were found in the longitudinal smooth muscle. A concentration of 2 nM ICI 118.551 completely displaced all grains in the circular smooth muscle and partly displaced those found in the longitudinal smooth muscle. A high concentration of ICI 118.551 (1 microM) displaced all grains above background from the smooth muscle. It is concluded that the circular smooth muscle only contains beta 2-adrenoceptors, while longitudinal smooth muscle may contain a proportion of beta 1-adrenoceptors. Whether such a location of beta adrenoceptors can be related to the beta 1-adrenoceptor-mediated inhibition of colon motility can not be clarified from these studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Partial agonism and functional selectivity: a study on beta-adrenoceptor mediated effects in tracheal, cardiac and skeletal muscle

Colterol, procaterol, sulfonterol, terbutaline and three monophenolic derivatives of terbutaline were examined with respect to their ability to react in vitro on beta-adrenoceptors in tissues isolated from guinea-pig. The effects measured were a) relaxation of the tracheal smooth muscle (mostly beta 2), b) depression of subtetanic contractions of the soleus muscle (beta 2), and c) increase in the force of the papillary muscle of the left ventricle (beta 1). Antagonistic effects were measured against isoprenaline as an agonist. The compounds studied showed a wide variation in selectivity, potency and intrinsic activity. All agonists showed a pronounced beta 2-selectivity, in general characterized by a higher intrinsic activity at beta 2- than at beta 1-adrenoceptors, while differences in affinity, as judged from the pA2-values were small. Partial agonists, such as sulfonterol, which did not cause a complete relaxation of a moderately contracted tracheal muscle, produced identical concentration-response curves from the trachea and soleus muscle. It is concluded that partial agonism at beta 1-adrenoceptors is an important factor for functional selectivity of beta 2-adrenoceptor agonists. On the other hand there seems to be no useful differences between the maximum effect elicited by a partial beta 2-adrenoceptor agonist on the skeletal muscle as compared with airway smooth muscle.

Effects of the selective beta 2-adrenergic agonists, procaterole and terbutaline, on protein secretion by rat submandibular glands

We examined the secretory effects of two beta 2-adrenergic agonists, procaterole and terbutaline, on the submandibular glands of anesthetized rats. After stimulation with these agents with and without a range of antagonists (non-specific alpha- and beta-adrenergic blockers), submandibular saliva was collected. The flow rate, protein concentration, the electrophoretic patterns, and amino acid composition of saliva were examined. These parameters were compared with their counterparts in saliva stimulated with isoproterenol (IPR), with and without antagonists. Assessed by these criteria, secreted proteins were classified as the alpha- or beta-type. In addition, IPR-stimulated proteins were compared in submandibular saliva of rats chronically treated with IPR or procaterole. Both beta 2-agonists were potent secretagogues for the submandibular glands of rats. All beta-antagonists completely abolished the secretory effects elicited by both beta 2-agonists, with the exceptions of carteolol and propranolol. However, no blocking agent abolished the secretory effects of IPR (60 mg/kg). The types of proteins in all submandibular saliva samples elicited by both beta 2-agonists with and without antagonists were the beta-type. Enlargement of the submandibular glands was not observed in rats subjected to chronic administration of procaterole, nor were abnormal and additional proteins observed, as confirmed by electrophoresis and by the amino acid analyses.

Beta 2-adrenoceptor-induced hypotension in the ganglion-blocked angiotensin II-supported rat

An in vivo method is described to demonstrate vascular beta 2-adrenoceptor agonist and antagonist activity. Agonist activity was shown by the ability of i.v. injected compounds to reduce blood pressure in ganglion-blocked, phenoxybenzamine-treated, angiotensin II-supported rats. Procaterol was employed to assess the relative beta 2 blocking activity of propranolol IPS 339 and atenolol. Arunlakshana and Schild analysis of the data revealed that all these compounds were competitively beta 2 antagonists, their relative potencies being 100 : 80 : 0.56 respectively.

Cardiostimulatory effects of prenalterol, a beta-1 adrenoceptor partial agonist, in vivo and in vitro. Correlation between physiological effects and adenylate cyclase activity

The cardiostimulatory effects of prenalterol, a beta-1-adrenoceptor partial agonist, were studied in vivo and in vitro and compared to those evoked by isoprenaline, a full agonist, and to those of other partial agonists. In the anaesthetized rat, prenalterol and terbutaline were found not to elevate the myocardial cyclic AMP content; this was in sharp contrast to isoprenaline. Both partial agonists did, however, produce significant effects on heart rate. In the anaesthetized cat, prenalterol exhibited chronotropic and inotropic intrinsic activities of 88 and 76% respectively in relation to isoprenaline. No statistically significant increase in myocardial cyclic AMP content could however be detected. Prenalterol did not stimulate adenylate cyclase significantly in the cat myocardial homogenate. This was also true of the beta-2-adrenoceptor selective partial agonist procaterol. In this preparation, isoprenaline, noradrenaline and adrenaline acted as full agonists. Furthermore, prenalterol produced a concentration-dependent inhibition of isoprenaline-activated adenylate cyclase. Our data indicate that maximal cardiac stimulation occurs at a low level of adenylate cyclase activation and low myocardial cyclic AMP concentration when provoked by a full beta-adrenoceptor agonist. The maximal physiological effects of a partial agonist such as prenalterol may consequently be achieved at a marginal activation of the adenylate cyclase. The present data may thus support the hypothesis of a large beta-adrenoceptor reserve for full agonists in the heart.

Effects of beta-adrenoceptor agonists on airway smooth muscle and on slow-contracting skeletal muscle: in vitro and in vivo results compared

Ten beta-adrenoceptor agonists were examined with respect to a) relaxation of pilocarpine-contracted trachea and depression of contractions of the soleus muscle of the guinea-pig in vitro and b) counteraction of histamine-induced bronchospasm and depression of contractions of the soleus muscle of the cat in vivo. There was a close correlation between the results obtained in vitro and results obtained on the corresponding tissues in vivo in spite of the different species used. A close correlation was also observed between effects on airway smooth muscle and on the soleus muscle contractions in vitro as well as in vivo for all compounds examined.