Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SYMPATHOMIMETICS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMedDate not supplied

Intrinsic sympathomimetic activity of labetalol.

In intact cats, cumulative doses (0.1-10 mg/kg i.v.) of labetalol produced dose-dependent decreases in heart rate and arterial blood pressure and dose-dependently reduced i.v. phenylephrine induced pressor responses. In spinal cats devoid of resting sympathetic tone, labetalol (1 mg/kg i.v.) produced a sustained elevation of heart rate and a transient fall in arterial blood pressure. In reserpine-pretreated, adrenalectomized cats, labetalol produced quantitatively the same effects as in spinal cats, indicating that the cardiovascular effects observed in cats with no resting sympathetic tone are due to a direct action of labetalol rather than via catecholamine release. The elevated heart rate due to labetalol in spinal cats was reduced by subsequent administration of the beta-adrenergic receptor antagonist, propranolol. Further, pretreatment with propranolol prevented the tachycardic and depressor effects of labetalol in spinal cats. In a separate group of spinal cats, labetalol administered in cumulative doses of up to 1 mg/kg i.v., produced graded increases in heart rate and also dose dependently reduced i.v. isoproterenol-induced tachycardic responses. Pindolol, a beta-adrenergic receptor antagonist with partial beta-agonist activity, produced similar effects in spinal cats at cumulative doses of 1-30 micrograms/kg. These results indicate that the alpha- and beta-adrenergic receptor antagonist, labetalol possesses partial beta-adrenergic receptor agonist activity. This intrinsic sympathomimetic action of labetalol appears to be more sustained on cardiac than on vascular beta-adrenergic receptors.

Adrenal Glands↗
PubMedDate not supplied

A comparison of the effects of beta-blockers with and without intrinsic sympathomimetic activity on hemodynamics and left ventricular function at rest and during exercise in patients with coronary artery disease.

The effects on hemodynamics and left ventricular function of propranolol and pindolol, beta-blockers without and with intrinsic sympathomimetic activity (ISA), respectively, were compared in six men with stable exertional angina at rest and during symptom-limited bicycle exercise. The study was controlled and double blinded, and the order of drug administration was randomized. The dosage of each drug (propranolol 0.15 mg/kg i.v., pindolol 0.02 mg/kg i.v.) was chosen to reduce exercise tachycardia by approximately 18%. Exercise capacity and duration were similar after each drug, and both drugs similarly reduced ST depression during exercise. At rest, propranolol significantly reduced heart rate, systolic arterial pressure, rate-pressure product, stroke volume index, cardiac index, and left ventricular ejection fraction, and increased systemic vascular resistance. In contrast, pindolol significantly reduced only the rate-pressure product and cardiac index, and to a lesser extent than propranolol. During exercise on the other hand, both drugs reduced the heart rate, arterial pressure, rate-pressure product, and cardiac index to a similar degree. Neither drug altered pulmonary artery wedge pressure, systemic vascular resistance, stroke volume index, left ventricular ejection fraction, or left ventricular end-diastolic and end-systolic volume indices. At equipotent beta-blocking dosages, ISA in pindolol reduced the effects of beta-blockade on resting hemodynamics and left ventricular function compared to propranolol, but during exercise the influence of ISA was reduced; and both pindolol and propranolol exert similar effects on hemodynamics and left ventricular function.

Adult↗
PubMed1988

A new water-soluble, selective beta-blocker with intrinsic sympathomimetic activity (ICI 141.292) in angina pectoris.

In a placebo-controlled, randomized double-blind study the effect of ICI 141.292 (beta 1-selective beta-blocker with intrinsic sympathomimetic activity = ISA) was studied in 11 patients with severe angina pectoris. The doses used were 100, 200 and 300 mg once daily. The 24-hour heart rate was significantly reduced by all regimens, and the Holter-monitoring pattern indicated the presence of ISA-effect at least 20 hours after the 300-mg dose. Maximal heart rate and blood pressure were significantly reduced and exercise duration increased during a symptom-limited bicycle exercise test on 200 and 300 mg, but not on 100 mg daily. Resting heart rate and blood pressure were uninfluenced on all regimens. ICI 141.292 is an effective agent in patients with severe angina pectoris. The response pattern suggests the presence of clinically relevant ISA.

Adrenergic beta-Antagonists↗
PubMed1979

Cross-over study of the efficacy of four beta 2-sympathomimetic bronchodilator aerosols.

1 Bronchodilator efficacy of four beta 2-sympathomimetic aerosols, fenoterol, orciprenaline, salbutamol and terbutaline has been compared in nine patients with chronic stable reversible airways obstruction using a double-blind placebo controlled cross-over design. Two puffs of each agent were given on two separate occasions to each of the patients and the forced expiratory volume in one second (FEV1) and the vital capacity (VC) were measured before and 30, 90, 150 and 210 min after administration. 2 Multivariate analysis of the data at 30 min showed FEV1 and VC in these patients to be so highly correlated that they could be considered as a single variable. 3 When absolute change in VC at 30 min was used as the response criterion, efficacy of the four drugs was significantly better than placebo (P < 0.01). It was not possible to rank all four drugs in order of effectiveness; fenoterol and salbutamol were significantly better than terbutaline and orciprenaline (P < 0.01) but this was complicated by a significant interaction effect between drugs and patients (P < 0.01). 4 Similar results were obtained when absolute and relative changes in FEV1 and VC and area under the curve were used as response variables. 5 The study demonstrates that important individual differences in patient response may be concealed if only average drug effects are considered.

Adrenergic beta-Agonists↗
PubMedDate not supplied

The alpha-sympathomimetic midodrin as a tool for diagnosis and treatment of sperm transport disturbances.

The present study was performed to determine the usefulness of the alpha-sympathomimetic midodrin for diagnosis and treatment of functional sperm transport disturbances. 140 andrological patients consulting due to severe oligozoospermia, hypospermia or partial/complete retrograde ejaculation were included. Ejaculates were examined 30 min after intravenous injection of 5-15 mg midodrin. Sperm concentration, motility and alpha-glucosidase as a marker of both epididymal function and sufficient passage through the vasa deferentia and the ejaculatory duct were measured and the values compared to those in the ejaculates obtained before therapy. In 23 of 140 patients, sperm concentration or total sperm count was improved by more than 10 million spermatozoa ml-1 or 20 million spermatozoa per ejaculation. Alpha-glucosidase in the seminal plasma increased in two cases. The present study demonstrates that severe oligozoospermia may be caused by functional transport disturbance of semen from the epididymis to the efferent duct system. In these cases, midodrin is of diagnostic and therapeutic value; however, it should be emphasized that its effectiveness cannot be predicted individually.

Ejaculation↗
PubMed1977

The effect of intrauterine fetal transfusion and a beta-sympathomimetic substance on the lecithin/sphingomyelin ratio in human amniotic fluid.

The apparently low incidence of respiratory distress syndrome in babies born prematurely after intrauterine transfusion and the simultaneous prophylactic administration of intravenous isoxsuprine (a beta-sympathomimetic agent) was investigated by serial study of amniotic fluid lecithin/sphingomyelin ratios. The ratio rose very significantly after intrauterine transfusions and significantly (but less markedly) after the administration of intravenous isoxsuprine alone.

Amniotic Fluid↗
PubMed1994

Release of endogenous ATP from the vasa deferentia of the rat and guinea-pig by the indirect sympathomimetic tyramine.

1. Adenosine 5'triphosphate (ATP) as well as [3H]-noradrenaline ([3H]-NA) is released by perfusion of the vas deferens with the indirect sympathomimetic tyramine (100 microM); this result is consistent with the concept of sympathetic cotransmission. 2. While tyramine produced a strong contraction in the vas deferens of the rat, it had little mechanical action in the guinea-pig vas deferens. This appears to be largely because tyramine induces considerably lower levels of release of both ATP and NA from the guinea-pig vas deferens compared to that of the rat. Furthermore, NA released by tyramine appears to release ATP from a secondary pool in the rat vans deferens, but not that of the guinea-pig, since prazosin reduced the tyramine-induced release of ATP in the rat vas deferens. 3. alpha,beta-Methylene ATP (alpha,beta-meATP) increased both the spontaneous release of ATP and the tyramine-evoked efflux of ATP and [3H]-NA. The basal and tyramine-induced efflux of [3H]-NA was also enhanced by the alpha 1-adrenoceptor antagonist, prazosin, suggesting that prejunctional alpha 1-adrenoceptors may modulate neurotransmitter release.

Adenosine Triphosphate↗
PubMed1996

Effect of beta-blocking agents with and without intrinsic sympathomimetic activity on work efficiency in healthy men.

In order to evaluate the effect of beta-blocking agents with and without intrinsic sympathomimetic activity (ISA) on work efficiency in healthy subjects, we studied the haemodynamic and gas exchange parameters, as well as blood lactate concentrations, during a graded maximal bicycle exercise test performed after perorally given propranolol (PRO) and pindolol (PIN) in seven healthy men. The medications (PRO: 80 mg x 2/day, PIN: 10 mg x 2/day, for seven days) were given in a placebo (PLA) controlled, double-blind, randomized, cross-over fashion. Both the drugs reduced heart rate and blood pressure during exercise equally compared with the placebo. The oxygen uptake at submaximal work loads, as well as at the maximum, was constantly and equally reduced by PRO and PIN compared with PLA. The anaerobic threshold was reached at a slightly lower oxygen uptake for both the drugs compared with the placebo (P < 0.05). No significant difference was, however, observed in the work levels at which the ventilatory anaerobic threshold was reached. Moreover, the gross efficiency, i.e. the amount of work performed at a certain energy consumption level (aerobic + anaerobic), was increased by both PRO (26.7 +/- 0.5%, P < 0.02 vs PLA: 24.7 +/- 0.5%) and PIN (26.5 +/- 0.5%, P < 0.05 vs PLA) at a submaximal work load of 240 W. The results indicate that beta-blocking agents propranolol and pindolol slightly and equally reduce maximal work performance, but increase the efficiency of submaximal work in a way that a certain amount of external work can be done with smaller consumption of oxygen. These findings may contribute to the benefit of beta-blocking agents in patients with coronary heart disease.

Adrenergic beta-Antagonists↗
PubMed1971

Actions of noradrenaline, other sympathomimetic amines and antagonists on neurones in the brain stem of the cat.

1. The effects of (-)-noradrenaline ((-)-NA) and related compounds on brain stem neurones in decerebrate unanaesthetized cats have been investigated using the technique of iontophoretic application from micropipettes.2. Four types of response to (-)-NA have been described. These were short lasting inhibition, long lasting inhibition, excitation, and a biphasic response consisting of short lasting inhibition followed by excitation. A variable amount of desensitization of the excitatory response, but not of inhibitory responses, was observed.3. Experiments in which small currents were used to pass (-)-NA from pipettes with smaller tips did not lead to any appreciable change in the proportions of neurones excited or inhibited.4. A variety of sympathomimetic agonists was tested. Short lasting inhibition was less sensitive than excitation to changes in molecular structure. Long lasting inhibition was more sensitive to molecular change and was not mimicked by some of the agonists which mimicked short lasting inhibition.5. Although agonists without one ring hydroxyl had weaker effects than those with both, compounds in which both ring hydroxyl groups were absent (beta-hydroxyphenylethylamine, ephedrine and amphetamine) mimicked excitation strongly. It is possible that the compounds without both ring hydroxyl groups had some effect other than simple agonistic activity.6. A dissociation was observed between responses to dopamine and (-)-NA. p-Tyramine mimicked dopamine, rather than (-)-NA.7. Neither the alpha-agonist, phenylephrine nor the beta-agonist, isoprenaline mimicked neuronal responses to (-)-NA. The alpha-antagonists phentolamine and phenoxybenzamine and the beta-antagonists dichloroisoprenaline, propranolol and D(-)-INPEA and combinations of propranolol with phentolamine or phenoxybenzamine were ineffective in blocking either excitation or inhibition. Thus, the central receptors appear to be different from peripheral alpha- and beta-receptors.8. The most effective antagonist of excitation was (-)-alpha-methylnoradrenaline. Metaraminol and dihydroergotamine also had some antagonistic activity. None of the compounds tested blocked inhibition. The effects of (-)-alpha-methylnoradrenaline have been discussed in relation to the hypotensive action of alpha-methyldopa.

Amphetamine↗
PubMed1972

Actions of the sympathomimetic bronchodilator, rimiterol (R798), on the cardiovascular, respiratory and skeletal muscle systems of the anaesthetized cat.

1. The actions of rimiterol [erythro(3,4-dihydroxyphenyl, 2-piperidyl methanol hydrobromide)], a new sympathomimetic bronchodilator, have been compared with those of salbutamol and laevoisoprenaline on the heart and lungs, and on contractions of the soleus muscle of cats under chloralose anaesthesia.2. Rimiterol and salbutamol injected intravenously were about equipotent in all tests, and were about 8 times less potent than laevoisoprenaline both in opposing the bronchoconstrictor action of 5-hydroxytryptamine, and in decreasing the tension and degree of fusion of incomplete tetanic contractions of the cat soleus muscle. They were about 19 times less potent than laevoisoprenaline in increasing heart rate.3. The effect on the soleus muscle is considered to be analogous to the muscle tremor that often occurs in man, and the results therefore suggest that systemic administration of bronchodilator doses of rimiterol, like salbutamol, may produce muscle tremor as an unwanted side-effect.4. When equipotent doses to oppose 5-hydroxytryptamine-induced bronchospasm were compared, rimiterol and salbutamol produced less tachycardia than did laevoisoprenaline. In order to match the tachycardia produced by laevoisoprenaline, the doses of rimiterol or salbutamol had to be increased about two and a half times. This safety margin for salbutamol in the cat is considerably less than that reported by others for different species, which suggests that beta(1)- and beta(2)-adrenoceptors may be less clearly differentiated in the cat than they are in other laboratory animals.

Amino Alcohols↗
PubMed1992

Influence of inhibition of extraneuronal uptake and of O-methylation on the hyperglycaemia caused by sympathomimetic amines in depancreatized rats.

This study aimed at testing whether the O-methylating system (extraneuronal uptake + O-methylation) modulates, in-vivo, beta-adrenoceptor-mediated responses. The influences of U-0521 (3,4-dihydroxymethylpropiophenone, an inhibitor of catechol-O-methyl transferase (COMT)) and hydrocortisone (an inhibitor of extraneuronal uptake) on the hyperglycaemia evoked by isoprenaline and adrenaline were compared. Both inhibitors enhanced the increase of the plasma glucose level induced by either isoprenaline (0.36 nmol kg-1 min-1) or adrenaline (0.55 nmol kg-1 min-1). The enhancement caused by U-0521 developed faster than that caused by hydrocortisone, but was of the same magnitude. This is the first report of supersensitivity to sympathomimetic amines caused by inhibition of either COMT or extraneuronal uptake in-vivo and for a response not involving smooth muscle cells.

Analysis of Variance↗
PubMed1986

Influence of intrinsic sympathomimetic activity on respiratory function during chronic beta blockade: comparison of propranolol and pindolol.

The long term effect of beta blockers and the influence of intrinsic sympathomimetic activity on respiratory function were assessed in patients with chronic stable angina pectoris randomised to receive treatment with propranolol (n = 21) or pindolol (n = 19) for one year. Forced expiratory volume in one second (FEV1) had fallen by a mean of 240 ml after one year (p less than 0.001) in those treated with propranolol compared with 120 ml in those treated with pindolol (p less than 0.05). The difference between the groups was significant (p less than 0.01). Vital capacity fell significantly only in those treated with propranolol (p less than 0.05 at one year). In those in whom the basal ratio of FEV1 to forced vital capacity was low (less than 70%) propranolol, but not pindolol, caused a significant (p less than 0.05) fall in FEV1 throughout treatment. Long term administration of pindolol has a less adverse effect on respiratory function than propranolol, which results in a progressive deterioration in respiratory function over one year.

Forced Expiratory Volume↗
PubMed1983

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

In vitro studies on the new beta-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, alpha 1-adrenergic blocking, or calcium antagonistic properties. Biochemical receptor binding studies are in general agreement with the observations from the isolated tissue experiments.

Acetamides↗
PubMed1991

Effects of the R(+)- and S(-)-isomers of beta-adrenoceptor blockers with intrinsic sympathomimetic activity, befunolol and carteolol, on rabbit intraocular pressure.

Effects of the R(+)- and S(-)-isomers of befunolol and carteolol, beta-adrenoceptors with intrinsic sympathomimetic activity, on the rabbit intraocular pressure were tested. The intraocular pressure was decreased by instillation of the R(+)- and S(-)-isomers of befunolol (0.1 and 0.3%) and of carteolol (1.0%) to the eye and attained the minimum level at 60 min. However, 0.3% of the R(+)- and S(-)-isomers of carteolol did not influence the pressure. The corresponding time courses for the intraocular pressure for the R(+)- and S(-)-isomers did not differ, suggesting that in the treatment of glaucoma, the therapeutic advantage of the R(+)-isomers of befunolol and carteolol may be similar to the S(-)-isomers.

Adrenergic beta-Antagonists↗
PubMed1979

Immunological release of histamine from human lung. I. Studies on the beta 2-sympathomimetic stimulator fenoterol.

Human lung tissue passively sensitized with anti-grass pollen IgE antibodies release histamine upon exposure to specific grass pollen antigen. Fenoterol, a beta 2-sympathomimetic stimulator drug, is shown to be a potent inhibitor of antigen-induced release of histamine. This inhibitory effect occurred with fenoterol concentrations of 2 x 10(-8) to 1 x 10(-7) M, and was determined by 67 and 95%, respectively. Thus, the beta 2-receptor stimulator fenoterol is a valuable drug for treating allergic bronchial asthma since it exhibits a combination of prophylactic and direct therapeutic properties.

Asthma↗
PubMed1986

Hemodynamic-inotropic response to beta-blocker with intrinsic sympathomimetic activity in patients with congestive cardiomyopathy.

The rest and exercise hemodynamic-inotropic response to administration of the beta-blocker pindolol was evaluated in 10 patients with congestive cardiomyopathy to determine whether the intrinsic sympathomimetic activity (ISA) of this agent may preserve ventricular function in the setting of beta-blockade. A significant (p less than .05) rise in systemic and pulmonary vascular resistance and a decline in stroke volume and cardiac index was observed after a single 10 mg dose. The change in cardiac index was negatively correlated with free drug concentration (r = -.59, p less than .01); the change in pulmonary and systemic vascular resistance showed a positive correlation with plasma concentration (r = .67, r = .57, respectively; all p less than .05). The response to exercise reflected a predominant beta-blocking effect, with a significant decrease in peak heart rate and cardiac index and an increase in pulmonary vascular resistance. There were no significant changes in variables of right or left ventricular inotropy after administration of the drug. The mean baseline plasma norepinephrine concentration for the population was 609 +/- 172 pg/ml (normal = 196 +/- 7 pg/ml) and was markedly elevated in two patients (931 and 2053 pg/ml) who developed severe pindolol-induced hypotension. Renin increased markedly in these two patients, but decreased in each of the remaining eight patients. These data indicate that although inotropy is not adversely affected by pindolol, increased afterload, which appears to be mediated by peripheral beta-blockade, results in a reduction in ventricular performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗