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Biomedical subjects

J Trap-Jensen

Publications and source records attributed to J Trap-Jensen.

At least 73 records · Page 4Linked to original sources
PubMed1981

Systemic and forearm haemodynamic and metabolic effects of racemic propranolol or D-propranolol in healthy subjects.

1. The immediate haemodynamic and metabolic effects of intravenous administration of DL-propranolol and D-propranolol were studied in healthy male subjects at rest and during dynamic forearm exercise. The dose of DL-propranolol and of D-propranolol was 0.1 and 1.0 mg/kg body weight respectively. 2. DL-Propranolol reduced heart rate significantly at rest, during forearm exercise and post-exercise, whereas D-propranolol had a lesser effect on heart rate which was significant only at the end of the exercise period. Arterial blood pressure and forearm blood flow were unchanged after either drug. 3. Both drugs reduced the release of lactate from the exercising forearm. Forearm exchange of oxygen, glucose, free fatty acids and triglycerides remained unchanged. 4. The arterial blood glucose concentration increased after D-propranolol, but was unchanged after DL-propranolol. The arterial serum free fatty acid concentration decreased after DL-propranolol, but was not changed after D-propranolol. Arterial concentrations of lactate and triglycerides were not influenced by the drugs. 5. The chronotropic response to beta-adrenoceptor blockade appears to be stereoselective, suggesting specific blockade of beta-adrenoceptors. Metabolic responses to beta-adrenoceptor blockade are difficult to explain in terms of the known adrenoceptor system and may be due to non-specific actions of beta-adrenoceptor antagonists. An exception is inhibition of lipolysis, which is probably mediated via beta-adrenoceptors.

Adult↗
PubMed1981

Immediate central and peripheral haemodynamic effects of a new vasodilating agent Pinacidil (P1134) in hypertensive man.

The purpose of this study was to evaluate the immediate central and peripheral haemodynamic effects of a new vasodilating agent P 1134, in hypertensive man. After oral administration of 25 mg P 1134, the maximal haemodynamic changes were (mean +/- 1 SEM): mean blood pressure fell from 121.8 +/- 6.5 to 80.5 +/- 7.8 mmHg, heart rate increased 24.2 +/- 4.5 beats/min, cardiac output rose 2.9 +/- 0.3 1/min and forearm blood flow increased 1.0 +/- 0.1 ml/100 ml tissue/min. Stroke volume increased 17.0 +/- 2.1 ml and the inotropic state of the heart as judged from systolic time intervals increased. Total peripheral resistance and forearm vascular resistance were both reduced by approx. 50%. Linear correlations were found between the serum concentration of P 1134 and the change in mean blood pressure and total peripheral resistance. Changes in the other parameters mentioned above occurred progressively with changes in mean blood pressure and total peripheral resistance. It can be concluded that P 1134 is a very potent hypotensive agent with a haemodynamic profile identical to that seen with vasodilators with preferably act on precapillary resistance vessels. Potency and maximal efficacy exceeds that of hydralazine and seems like that of minoxidil. P 1134 is remarkably free from side-effects apart from causing water retention as all other vasodilators. It can be administered orally as well as intravenously. This makes P 1134 a very interesting compound in the treatment of moderate to severe hypertension, and further studies are well-founded.

Adult↗
PubMed1981

Central and peripheral haemodynamic effects of prenalterol in patients with coronary heart disease.

The acute haemodynamic effects of prenalterol, a selective adrenergic beta-I-receptor agonist were studied in eight patients with coronary heart disease. Prenalterol was administered intravenously in four increasing doses to a cumulative dose of 5.6 mg. Fifteen minutes after the last dose of prenalterol two doses of the selective adrenergic beta-I-receptor antagonist metoprolol were administered intravenously to a cumulative dose of 17-5 mg. Ten minutes after each dose cardiac output, heart rate, arterial blood pressure, pulmonary artery pressure, systolic time intervals and forearm blood flow were determined. Haemodynamic effects of prenalterol: cardiac index and heart rate increased maximally by 38% and 39% respectively. Stroke index was increased by 6-9% after the first and second dose. Mean blood pressure was increased by 9.8 mmHg. Total peripheral resistance index was reduced by 19%. The mean pulmonary artery pressure decreased by 3.8 mmHg and pulmonary resistance index was reduced by 48%. Systolic time intervals were all reduced significantly after the second dose, which reflected the positive inotropic effects of prenalterol. Forearm blood flow increased by 29% and forearm vascular resistance was decreased by 20%. Haemodynamic effects of metoprolol: the haemodynamic changes induced by prenalterol were stepwise counteracted by metoprolol. After the second dose all the haemodynamic variables had returned to the control levels. It is concluded that prenalterol possesses a considerable positive inotropic as well as positive chronotropic effect on the myocardium. Both the chronotropic and inotropic effect of prenalterol was counteracted by metoprolol.

Blood Pressure↗
PubMed1980

Immediate haemodynamic effects of prenalterol, a new adrenergic beta-1-receptor agonist, in healthy volunteers.

The acute haemodynamic effects of prenalterol, a selective adrenergic beta-1-receptor agonist, were studied in eight healthy male volunteers. Prenalterol was administered i.v. in five increasing doses to a cumulative dose of 5.55 mg. After the last dose of prenalterol, three doses of the selective adrenergic beta-1-receptor antagonist metoprolol were administered i.v. to a cumulative dose of 17.5 mg. After each dose, cardiac output (CO), stroke volume (SV), blood pressure (BP), heart rate (HR), systolic time intervals (STI) and forearm blood flow (FBF) were determined. Prenalterol had the following effects: CO was significantly increased by 21.0% after the fourth dose, but the fifth dose did not further change CO. SV was unchanged after the first four doses, but after the fifth dose a significant decrease in SV of 7.0% was seen. Mean BP was increased significantly by 7.7%, but diastolic BP remained unchanged. HR was increased by 28.4%. Total peripheral resistance was reduced by 8.8%. STI were reduced significantly after the second dose, which indicates that prenalterol has a positive inotropic action. FBF was increased significantly after the fourth dose. After the third dose of metoprolol, the CO, SV, means BP, HR, STI and FBF had returned to their control values. It is concluded that prenalterol has positive inotropic and chronotropic effects on the myocardium, and that metoprolol is a specific antidote.

Adolescent↗
PubMed1980

A comparison of the acute haemodynamic effects of propranolol and pindolol at rest and during supine exercise in man.

1. Dose-response curves for heart rate, cardiac output, arterial blood pressure and pulmonary artery pressure were obtained in 16 male patients after intravenous administration of three increasing doses of pindolol, propranolol or placebo. All patients had an uncomplicated acute myocardial infarction 6-8 months earlier. 2. The dose-response curves were obtained at rest and during repeated bouts of supine bicycle exercise. The cumulative dose amounted to 0.024 mg/kg body weight for pindolol and to 0.192 mg/kg body weight for propranolol. 3. At rest propranolol significantly reduced heart rate and cardiac output by 12% and 15% respectively. Arterial mean blood pressure was reduced by 9.2 mmHg. Mean pulmonary artery pressure increased significantly by 2 mmHg. Statistically significant changes in these variables were not seen after pindolol or placebo. 4. During exercise pindolol and propranolol both reduced cardiac output, heart rate and arterial blood pressure to the same extent. After propranolol mean pulmonary artery pressure was increased significantly by 3.6 mmHg. Pindolol and placebo did not change pulmonary artery pressure significantly. 5. The study suggests that pindolol may offer haemodynamic advantages over beta-receptor-blocking agents without intrinsic sympathomimetic activity during low activity of the sympathetic nervous system, and may be preferable in situations where the beta-receptor-blocking effect is required only during physical or psychic stress.

Adult↗
PubMed1980

Haemodynamic and metabolic effects of combined adrenergic alpha- and beta-receptor blockade with labetalol in the exercising human forearm.

At rest supine acute intravenous administration of the combined adrenergic alpha- and beta-receptor blocking compound labetalol (1 mg/kg body weight) to young, healthy, male subjects, produced a clear-cut fall in arterial blood pressure. During dynamic forearm exercise, forearm blood flow decreased by 17.2%, and calculated vascular resistance increased by 11.3% after labetalol. Forearm oxygen uptake decreased (14.6%), suggesting an increased mechanical efficiency. Lactate release from the exercising forearm decreased (17.6%), probably because of the beta-receptor blockade. Forearm uptake of glucose and free fatty acids remained unchanged. Arterial blood glucose concentration attained a higher level after labetalol. Arterial plasma concentration of FFA was reduced during exercise and post-exercise probably because beta-receptor mediated lipolysis was antagonized.

Adult↗
PubMed1980

Comparison of four commercial Tc-99m(Sn)DTPA preparations used for the measurement of glomerular filtration rate: concise communication.

To find a commercially available DTPA preparation that could be used for the measurement of glomerular filtration rate (GFR), the plasma clearances of four different Tc-99m(Sn)DTPA preparations were compared with that of Cr-51 EDTA using a single-injection technique. One preparation yielded results identical to those obtained with Cr-51 EDTA, whereas the others underestimated the GFR to a varying degree. It is concluded that Tc-99m DTPA can be used to estimate the GFR, but that the accuracy will depend on the commercial source.

Chromium Radioisotopes↗
PubMed1980

Immediate haemodynamic and metabolic effects of intravenous labetalol in the exercising forearm.

Dynamic forearm exercise was performed in healthy subjects before and after intravenous labetalol, 1 mg/kg body weight. Labetalol produced a sustained fall in arterial blood pressure. Forearm blood flow decreased by 17.2% partly due to the reduced driving pressure and partly due to an increased vascular resistance. Forearm oxygen uptake decreased by 14.6%, suggesting an increased mechanical efficiency. Lactate release from the exercising forearm decreased by 17.6%. Forearm uptake of glucose and free fatty acids remained unchanged.

Blood Pressure↗
PubMed1980

Sequential haemodynamic effects of labetalol at rest and during exercise in essential hypertension.

The haemodynamic effects of labetalol were studied in patients with essential hypertension after acute and long-term administration. In the acute study 50 mg of labetalol was given i.v. to 10 patients. Eight of them were re-examined after three to four months of oral treatment with labetalol 300 mg t.i.d. Measurements were made at supine rest, after five minutes in the upright position, and after five minutes' supine bicycle exercise at 50 and 100 watt work loads. In the acute study cardiac output was unchanged except at the work load of 100 watt when it decreased 18%. The mean blood pressure decreased under all conditions, 11.6 mm Hg at supine rest, 22.3 mm Hg in the upright position and 15.9 mm Hg and 16.9 mm Hg at the two work loads. Heart rate was unchanged at supine rest, and reduced by 10% in the other situations. Total peripheral resistance was reduced significantly at rest in the supine and upright positions, but not during exercise. Pulmonary artery pressure was unchanged. In the long-term study cardiac output was unchanged except of the heavy work load when it decreased 11%. Mean blood pressure was reduced significantly by 14.6 mm Hg at supine rest, 16.8 mm Hg in the upright position and by 13.9 mm Hg and 13.4 mm Hg, respectively, at the two work loads. Heart rate was reduced significantly in all conditions by 10-14%. Total peripheral resistance decreased significantly at rest, but not during exercise, and pulmonary artery pressure was unchanged.

Blood Pressure↗
PubMed1980

Immediate effects of labetalol on central, splanchnic-hepatic, and forearm haemodynamics during pleasant emotional stress in hypertensive patients.

The effects of intravenous administration of labetalol in a dose of 0.75 mg/kg body weight on central, splanchnic-hepatic and forearm haemodynamics were studied in 8 hypertensive patients resting in the supine position and during pleasant psychic stress induced by practice of a television-game of tennis. In the resting state labetalol caused immediate reduction of arterial blood pressures and of total vascular resistance, whereas heart rate, cardiac output and splanchnic-hepatic and forearm blood flow remained unchanged. After labetalol, the stress-induced increase in heart rate, cardiac output, estimated myocardial oxygen demand and forearm blood flow was significantly reduced, whereas total vascular resistance and splanchnic-hepatic vascular resistance remained unchanged. This is taken to indicate that the alpha-adrenoceptor blocking properties of labetalol may offer haemodynamic advantages as compared to the widely used non-selective beta-adrenoceptor blocking agents in the management of hypertension.

Ethanolamines↗
PubMed1980

Effect of labetalol on plasma catecholamines at rest and during increased sympathetic activity.

Mean arterial blood pressure was decreased by intravenous labetalol in 14 hypertensive patients, resting in the supine position, when standing, during exercise and during psychic stress. Heart rate was unchanged during psychic stress and while resting in the supine position, whereas it fell in the other situations. Plasma noradrenaline increased in all situations after labetalol compared to control studies. Plasma adrenaline only increased when standing and during stress, and there was no correlation between changes in plasma noradrenaline and adrenaline. Blood glucose rose significantly after labetalol in the supine position, whereas it only tended to increase in the other experimental situations. The changes in plasma noradrenaline and blood glucose induced by labetalol are identical to those seen after pure alpha-adrenoceptor blockade. The beta-adrenoceptor blocking property of labetalol may contribute to the higher plasma concentration of noradrenaline when standing and during exercise as this has been found during pure beta-adrenoceptor blockade.

Adult↗