Oral tyramine challenge tests.
Explore the source record for details and available documents.
Blood Pressure↗
Biomedical subjects
I Berlin
Publications and source records attributed to I Berlin.
Tertatolol potentiates exercise-induced atrial natriuretic peptide release by increasing atrial diameter in healthy subjects.
To evaluate the contribution of atrial distension and/or adrenergic mechanisms in the regulation of atrial natriuretic peptide (ANP) secretion, plasma immunoreactive ANP, norepinephrine (NE), epinephrine (E), and left atrial diameter were measured at rest, during, and after graded upright standardised bicycle exercise in 8 healthy male subjects after single-dose administration of placebo, tertatolol (5 mg), prazosin (1 mg), or combination of tertatolol (5 mg) and prazosin (1 mg). Systolic and diastolic left atrial diameters were measured before, during, and just after exercise by bidimensional echocardiography. Exercise raised plasma ANP concentrations. This rise was greater on tertatolol alone and tertatolol and prazosin than on placebo or prazosin alone: mean area under the plasma ANP concentration curve increased by 35% on tertatolol alone, 45% on tertatolol and prazosin when compared with placebo (p < 0.01), and by 82 and 94%, respectively, when compared with prazosin alone (p < 0.01). The rise in plasma ANP was greater during the postexercise period: 80% for tertatolol alone, 67% for tertatolol and prazosin when compared with placebo (p < 0.01) and 133 and 115%, respectively, when compared with prazosin alone (p < 0.01). The rise in plasma ANP was accompanied by an increase in both systolic and diastolic atrial diameters which was significantly greater on tertatolol alone and on the tertatolol and prazosin combination than on placebo or prazosin alone (p < 0.001). Beta-blockade alone did not affect plasma catecholamine concentrations but exercise-induced increase in plasma NE was significantly potentiated by prazosin and the prazosin and tertatolol combination, and that of plasma E by the prazosin and tertatolol combination.(ABSTRACT TRUNCATED AT 250 WORDS)
Adrenergic beta-Antagonists↗
Comparison of the effects of zolpidem and triazolam on memory functions, psychomotor performances, and postural sway in healthy subjects.
Zolpidem is a rapid-onset, short-duration imidazopyridine hypnotic drug and is specific agonist of the omega-1 (BZD1) receptors. Its hypnotic characteristics resemble those of triazolam. The aims of this study were to assess the effects of zolpidem on memory (the main objective), psychomotor performances, and postural sway (secondary objectives) in 18 healthy subjects and to compare them with those of triazolam and placebo. Short- and long-term memory (paired words associate and pictures test), psychomotor performances (critical flicker fusion frequency, choice reaction time, digit symbol substitution test), and postural sway were evaluated before and 1.5, 4, 6, and 8 h after the administration of a single dose of zolpidem (10 mg), triazolam (0.25 mg), and placebo. For each assessment, the maximal effect for both hypnotic drugs occurred 1.5 hour after intake. Both drugs decreased psychomotor performance, impaired memory, and increased postural sway. The effects of both hypnotic agents were short lasting, and no alterations were found 6 and 8 hours, respectively, after drug intake. No clinically relevant differences were found between zolpidem and triazolam for memory, psychomotor performance, postural sway, or adverse effects. It may be concluded that zolpidem, like triazolam, impairs short- and long-term memory, psychomotor performances, and postural sway and that these effects are of short duration.
Adult↗
Dose ranging study of lansoprazole, a new proton pump inhibitor, in patients with high gastric acid secretion.
The effects of single doses and of 7 days of lansoprazole 10, 20 and 30 mg PO versus placebo on gastric acid secretion have been evaluated in 8 patients with high gastric acid secretion. The double blind crossover period was followed by a simple blind 7 days on placebo to detect any rebound phenomenon. After the first dose lansoprazole did not modify basal acid output (BAO) but it significantly and dose dependently inhibited peak acid output (PAO) and increased the time during which nocturnal intragastric pH was greater than 3. After 7 days of treatment the same significant, dose-dependent suppression of gastric acid was found, but BAO was also blocked. One week after cessation of lansoprazole administration no rebound increase in gastric acid-secretion was observed. The plasma gastrin concentration remained unchanged throughout the study.
2-Pyridinylmethylsulfinylbenzimidazoles↗
Comparative investigation of the effect of moclobemide and toloxatone on monoamine oxidase activity and psychometric performance in healthy subjects.
The effects of moclobemide and toloxatone, two reversible monoamine oxidase-A inhibitors, on biochemical parameters that reflect monoamine metabolism and on psychomotor performance parameters were investigated in a study in 12 healthy volunteers. Treatments were given double-blind in a randomized, placebo-controlled cross-over design, with 1 week wash-out between the treatments. Drugs were given thrice daily in the following doses: moclobemide 150-150-150 mg and toloxatone 400-200-400 mg. All assessments were performed on day 8 under standardized conditions. There was no difference with regard to adverse events between moclobemide and toloxatone: both drugs induced a slight decrease in both supine and standing heart rate. Judged on the basis of the area under the curve, the two MAO-inhibitors reduced the plasma levels of DHPG and HVA, with more pronounced effects for moclobemide than for toloxatone. After moclobemide MAO-A inhibition was almost constant over 24 h, whereas the effect of toloxatone was short lasting after each dose. The same differences were reflected in plasma 5-HIAA concentrations and urinary excretion of 3-methoxytyramine and normetanephine. Neither of the compounds tested had any influence on the memory, vigilance, mood, or sleeping habits of the subjects.
Adult↗
Assessment of the anticholinergic effect of the new antihistamine mizolastine in healthy subjects.
1. Twelve healthy subjects were enrolled in a double-blind placebo controlled cross-over study in order to assess the possible anticholinergic effects of four doses of a new antihistamine compound, mizolastine, compared with hyoscine butylbromide (HBB) used as a reference anticholinergic drug. 2. Although mizolastine, a potent and selective H1-receptor blocker has no affinity for muscarinic receptors and does not antagonize the effects of carbachol in rodents, a study was initiated to investigate its effects on various effectors possessing muscarinic receptors (eye, heart, sweat gland, salivary gland). 3. HBB (40 mg, s.c.) impaired accommodation, decreased salivary flow and inhibited cardiac sinus arrhythmia. Pupil diameter and maximum constriction speed, carbachol-induced skin sweating and Valsalva ratio were unaffected. 4. Mizolastine (5, 10, 20, 40 mg p.o.) did not affect any parameter at any time point, demonstrating a lack of anticholinergic effect.
Adult↗
The alpha 2-adrenergic receptor antagonist yohimbine inhibits epinephrine-induced platelet aggregation in healthy subjects.
Onset of sudden death, myocardial infarction, and stroke occurs more likely in the morning hours. Similarly, a morning increase in epinephrine-induced platelet aggregation was observed accompanied by an increase in plasma catecholamines. Inhibition of the morning increase in platelet aggregation would be of therapeutic benefit. In this study the effect of the selective alpha 2-adrenergic receptor antagonist yohimbine on platelet aggregation was evaluated in healthy subjects. Yohimbine administered orally selectively antagonized epinephrine but not collagen, arachidonic acid, or adenosine diphosphate-induced ex vivo platelet aggregation. The lowest dose of yohimbine that significantly inhibited epinephrine-induced platelet aggregation was 8 mg. The inhibitory effect of yohimbine on platelet aggregation lasted 10 hours with the 12 mg dose. At the doses studied (4, 8, and 12 mg), yohimbine did not modify blood pressure, standing heart rate, or plasma catecholamine or glucose concentrations. Twelve milligrams of yohimbine moderately but significantly accelerated supine heart rate (mean maximal increase, 7 +/- 3 beats/min). Further clinical studies are needed to evaluate whether bedtime administration of 12 mg yohimbine may block the morning increase in epinephrine-induced platelet aggregation.
Administration, Oral↗
Peripheral haemodynamic effects of smoking in habitual smokers. A methodological study.
The effect of smoking on forearm haemodynamics was studied in four groups of healthy subjects, who had all smoked cigarettes (10-15 cigarettes/day) on average for 10 years. Changes in heart rate, blood pressure, forearm blood flow, forearm vascular resistance and pulse wave velocity were determined before and every 15 min for 75 min after smoking two cigarettes within 10 min. The inhaled nicotine was about 2.2 mg. There was no significant difference between the four groups in any haemodynamic variable before or after smoking, which indicated adequate reproducibility of the parameters studied and so made it possible to pool the results from all 30 subjects. Smoking significantly increased blood pressure, heart rate and pulse wave velocity and decreased forearm blood flow. Forearm vascular resistance remained unchanged. The rises in systolic blood pressure and pulse wave velocity were transient and both peaked (7% and 28%, respectively) 15 min after smoking. In contrast, heart rate and diastolic blood pressure remained significantly elevated and forearm blood flow was significantly decreased throughout the 75 min follow-up. The maximal changes were: heart rate +34%, diastolic blood pressure +17%, and forearm blood flow -24%. It is concluded that smoking produces statistically significant changes in forearm haemodynamics affecting both small and large arteries. The reproducibility of the study design means that it can be used to evaluate substances which may antagonize the haemodynamic effects of tobacco smoking.
Adult↗
Beta-adrenoceptor blockade potentiates exercise-induced release of atrial natriuretic peptide.
The effect of a non selective and a cardio-selective beta-blocker on basal and exercise-stimulated plasma atrial natriuretic peptide concentrations in healthy volunteers has been studied. Nine healthy volunteers received single oral doses of 5 mg tertatolol, 100 mg atenolol or placebo, at one week intervals, in a double blind cross over trial. At rest plasma atrial natriuretic peptide, aldosterone, antidiuretic hormone and cyclic GMP concentrations and plasma renin activity were not modified by the treatments. During exercise plasma atrial natriuretic peptide concentrations were significantly increased by each treatment, the increment being significantly greater on beta-blockers than on placebo. The rise in atrial natriuretic peptide was 72% after placebo (from 24 to 42 pg/ml), 184% after atenolol (from 30 to 86 pg/ml), and 183% after tertatolol (from 34 to 95 pg/ml), respectively. Thus, the study has shown that in healthy subjects the plasma natriuretic peptide concentration is increased by exercise and that the increase is considerably and equally potentiated by selective and non selective beta-adrenoceptor blockade. The effect may be mainly due to a reduction in ventricular contractility with an increase in atrial pressure. The beta-blockers did not influence the resting plasma atrial natriuretic peptide levels, which suggests that in healthy subjects basal atrial natriuretic peptide secretion is not controlled via beta-receptors.
Adrenergic beta-Antagonists↗
Cicletanine does not affect plasma atrial natriuretic peptide concentration in healthy subjects.
The effect of 50 and 150 mg cicletanine, a new vasodilator antihypertensive, on plasma atrial natriuretic peptide (ANP), cyclic GMP and antidiuretic hormone has been investigated at rest and during standardized exercise, in a double blind cross over study in healthy subjects. Exercise significantly increased in plasma ANP, cyclic GMP and antidiuretic hormone concentrations, and cicletanine did not affect any of them either at rest or during exercise. Since the alpha-1 adrenoceptor blocker prazosine decreases, beta-adrenoceptor blockers increase and the vasodilator cicletanine does not alter the plasma ANP response to exercise, it is suggested that adrenergic receptors may be directly involved in the regulation of ANP secretion.
Administration, Oral↗
Evaluation and comparison of the interaction between alcohol and moclobemide or clomipramine in healthy subjects.
The interaction of clomipramine and moclobemide with alcohol was compared in a double blind parallel groups study in 24 healthy volunteers. Moclobemide was given at the highest recommended therapeutic dose (200 mg t.i.d.) and clomipramine in a subtherapeutic dose (25 mg b.i.d.) because of its poor tolerance in healthy subjects. Psychometric evaluations were performed during a placebo run-in phase; after a 5-day treatment period; assessments were made before, and again 1 h and 4 h after alcohol ingestion. Alcohol doses were pre-determined for each subject in order to produce a blood alcohol concentration of 0.6 g/l 1 h after alcohol intake and this individual alcohol dose was given on test days. The day before alcohol intake tests for autonomic functions were made to assess the anticholinergic effects of the drugs. Alcohol significantly increased body sway, decreased critical flicker fusion frequency, prolonged choice reaction time, impaired copying skills, impaired memory and increased the subjective feelings of satisfaction and tension. Drugs increased the effect of alcohol on body sway and this was essentially due to clomipramine. Clomipramine both without and with alcohol increased body sway, prolonged choice reaction time more than did moclobemide. Clomipramine seemed to diminish alcohol-induced memory impairment in one of the memory tests used. Subjects taking clomipramine had significantly more adverse effects after alcohol ingestion than did subjects of the moclobemide group. In contrast to moclobemide, clomipramine produced a moderate but significant drop in standing systolic blood pressure and a clear inhibition of salivary excretion.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Alterations in beta-adrenergic sensitivity and platelet alpha 2-adrenoceptors in obese women: effect of exercise and caloric restriction.
1. Peripheral adrenergic responses were studied in eight obese women before and after 15 days of caloric restriction (2500 kJ/day) and in eight sex- and age-matched lean controls. 2. beta-Adrenergic sensitivity (defined as the dose of isoprenaline required to increase resting heart rate by 25 beats/min) was evaluated before and after the diet. Density and affinity (determined as the apparent dissociation constant) of platelet alpha 2-adrenergic receptors, and plasma adrenaline and noradrenaline levels, were measured after overnight bed-rest and after 9 min of standardized exercise performed before and after the low caloric diet. 3. Before the diet basal antecubital venous plasma noradrenaline concentrations were lower in obese women when compared with lean women (0.94 +/- 0.06 vs 1.27 +/- 0.17 nmol/l, P less than 0.02). Isoprenaline sensitivity did not differ between lean and obese women. 4. At rest, platelet alpha 2-adrenoceptor density was lower in overweight than in lean women (129 +/- 21 vs 168 +/- 16 fmol/mg of protein, P less than 0.02). Exercise significantly increased platelet alpha 2-adrenoceptor density and decreased affinity in lean women. This decrease correlated with the rise in plasma noradrenaline. 5. In obese women exercise did not modify platelet alpha 2-adrenoceptor density or affinity, despite a significant increase in plasma catecholamines. However, the increase in plasma noradrenaline during exercise was lower in obese women. 6. The low caloric diet produced a beta-adrenergic supersensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Comparison of the monoamine oxidase inhibiting properties of two reversible and selective monoamine oxidase-A inhibitors moclobemide and toloxatone, and assessment of their effect on psychometric performance in healthy subjects.
1. The effects of two reversible, predominantly monoamine oxidase-A (MAO-A) inhibitors, moclobemide (150 mg three times daily) and toloxatone (400-200-400 mg day-1) on monoamine metabolites and psychometric performance were compared in a double-blind placebo controlled crossover study in 12 healthy subjects. 2. After 7 days of moclobemide/toloxatone/placebo administration subjects were hospitalized for 24 h on day 8. Blood samples were drawn every 2 h for determination of plasma noradrenaline (NA), 3,4-dihydroxyphenylglycol (DHPG), homovanillic acid (HVA) and 5-hydroxyindolacetic acid (5-HIAA). Urine was collected for measurements of normetanephrine and 3-methoxytyramine excretion. Psychometric performance (short- and long-term memory, critical flicker fusion frequency, choice reaction time) and subjective feelings were assessed before each drug intake (in the morning, at noon, in the evening). 3. Compared with placebo, both reversible monoamine oxidase inhibitors decreased the plasma concentration of DHPG and HVA. The overall fall in DHPG (AUC from 0 to 24 h) was 44% during moclobemide and 12% during toloxatone (P less than 0.001) and the overall decrease in HVA was 38% and 20% (P less than 0.005) on moclobemide and toloxatone, respectively. 4. Before the next drug intake, MAO-A inhibition, as judged by the decrease of plasma DHPG concentration, was significantly different from placebo with moclobemide but not with toloxatone. 5. Moclobemide, but not toloxatone, exerted a moderate, but significant inhibition of the deamination of 5-hydroxytryptamine (5-HT) as judged by the fall in plasma 5-HIAA concentration. Neither drug influenced plasma NA concentration. 6. A significant rise in urinary excretion of normetanephrine was observed on moclobemide and to a lesser extent on toloxatone. The urinary excretion of 3-methoxytyramine was significantly raised by moclobemide but not by toloxatone. 7. Neither moclobemide nor toloxatone altered memory function, vigilance, subjective feelings or sleep characteristics of the subjects.
Adult↗
Determination and comparison of the pressor effect of tyramine during long-term moclobemide and tranylcypromine treatment in healthy volunteers.
Monoamine oxidase inhibitors can elicit increases in systolic blood pressure after tyramine ingestion (cheese effect). Moclobemide is a new, reversible, preferential monoamine oxidase A inhibitor with antidepressant properties. Its potentiation of the tyramine pressor effect during 200 mg t.i.d. chronic treatment was compared with tranylcypromine, 10 mg b.i.d., in a double-blind, parallel-group, placebo-controlled study (n = 16). Tyramine was mixed with food and ingested in increasing daily doses, during a normal meal, until a systolic blood pressure increase of at least 30 mm Hg was achieved (tyramine 30). When compared with the usual fasting oral tyramine tests performed in the same subjects, the mean tyramine 30 dose with a meal was 2.8 times higher. The mean tyramine 30 dose with a meal decreased from 1450 mg (range, 800 to 2000 mg) during placebo to 306 mg (range, 150 to 500 mg) during moclobemide (factor, 5.0) and from 1200 mg (range, 1000 to 1600 mg) during placebo to 35 mg (range, 20 to 50 mg) during tranylcypromine (factor, 38.2). The duration of the systolic blood pressure increase was longer with tranylcypromine (126 minutes) than with moclobemide (69 minutes) (p less than 0.01).
Administration, Oral↗
Pharmacokinetic and pharmacodynamic comparison of two doses of long acting propranolol (80 and 160 mg) in healthy subjects.
1. The kinetics and dynamics of long acting propranolol 80 mg and 160 mg were examined after single oral doses to 12 healthy volunteers. 2. Long acting propranolol 160 mg produced a twofold increase in mean peak blood propranolol concentration and AUC compared with the lower dose. There was no difference in elimination half-life, bioavailability and mean residence time of propranolol between the two doses. 3. Resting pulse rate was decreased by long acting propranolol 160 mg but not by the lower dose. 4. Both preparations blocked exercise induced tachycardia during the entire observation period of 29 h. Percentage inhibition of exercise tachycardia was significant at all time points but long acting propranolol 160 mg exhibited a greater reduction at 24 h and 29 h. 5. Increase in systolic blood pressure during exercise was inhibited by both preparations during the entire observation period with no differences between them. 6. The doubling of the dose administered was reflected in blood concentrations but not in pharmacodynamic parameters. Few pharmacodynamic differences were found between the two doses.
Adult↗
Lack of interaction between nizatidine and warfarin during chronic administration.
Nizatidine is a new antagonist of H2 receptors. The nizatidine warfarin interaction was investigated in healthy volunteers during chronic warfarin (mean warfarin dose: 5 +/- 0.9 mg/d) and nizatidine (300 mg/d) administration. Nizatidine coadministration did not increase the prothrombin time, kaolin-cephalin clotting time, and did not modify the activity of clotting factors II, VII, IX, X. Nizatidine did not influence the steady-state plasma warfarin concentration.
Adult↗
Lack of hypoglycemic symptoms and decreased beta-adrenergic sensitivity in insulin-dependent diabetic patients.
Plasma epinephrine, norepinephrine, and dopamine responses were studied in insulin-dependent diabetic patients at rest, on standing and during insulin-induced hypoglycemia. beta-Adrenergic sensitivity was evaluated by the isoproterenol sensitivity test. Five men who had adrenergic symptoms during hypoglycemia and no severe hypoglycemic accidents (coma, seizures) (group A) and five men who had repeated severe hypoglycemic accidents but lack of adrenergic symptoms of hypoglycemia (group B) were studied. The mean resting plasma epinephrine was lower in group B (147 +/- 22 pmol/L, SEM) than in group A (398 +/- 98 pmol/L, P less than 0.02). On standing plasma epinephrine increased significantly in both groups. During hypoglycemia blood glucose decreased identically in the two groups; plasma epinephrine and norepinephrine increased significantly and to the same extent in both groups; the mean maximal heart rate was significantly greater in group A than in group B. Isoproterenol sensitivity (defined as the dose of isoproterenol required to increase heart rate by 25 beats/min) was lower in group B (5.87 +/- 1.12 micrograms) than in group A (2.37 +/- 0.22 micrograms, P less than 0.01). The group B patients had significantly fewer hypoglycemic symptoms during insulin-induced hypoglycemia than did group A patients. We conclude that decreased beta-adrenergic sensitivity contributes to the lack of adrenergic symptoms of hypoglycemia in insulin-dependent diabetic patients.
Adolescent↗
Hypoglycaemia unawareness.
Explore the source record for details and available documents.
Blood Glucose↗