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Biomedical subjects

J Trap-Jensen

Publications and source records attributed to J Trap-Jensen.

At least 19 recordsLinked to original sources
PubMed1992

Xamoterol in severe congestive heart failure: long-term oral treatment, a double-blind randomised study.

Twelve patients in severe congestive heart failure were given placebo, 100 mg xamoterol (Corwin) twice daily and 200 mg xamoterol twice daily, respectively, in 3 two-week periods in a double-blind randomised study. At the end of each treatment period the patients were evaluated. No differences were found between placebo and xamoterol in the following parameters: New York Heart Association function group index, heart volume, body weight, exercise duration on bicycle and treadmill, heart rate and systolic and diastolic blood pressure at rest. However, during exercise we found significantly lower heart rate and rate-pressure product during xamoterol treatment. This reduction is probably indicating occupation of beta-adrenoreceptors with concomitant reduced oxygen consumption during exercise.

Administration, Oral↗
PubMed1991

[Captopril renography in the diagnosis of renovascular hypertension].

The value of renography before and after angiotensin converting enzyme inhibition with captopril (captopril renography) as a test for renovascular hypertension was studied in fourteen hypertensive patients. The captopril renography was performed with 99mTc-DTPA by means of a gammacamera, allowing determination of single kidney glomerular filtration rate (SKGFR). In all patients determination of renal vein plasma renin concentration and renal angiography were carried out. Eleven patients showed an elevated unilateral renin secretion. All of these had a significant decrease of SKGFR in one or both kidneys after captopril. Three patients without a lateralized renal renin secretion showed no change in SKGFR. In five patients with presumed essential hypertension there was no change in SKGFR during captopril renography. Captopril renography with 99mTc-DTPA gammacamera renography is a promising tool for identification of unilateral increased renin secretion in hypertensive patients suspected of renovascular hypertension.

Adult↗
PubMed1991

Effects of vacusac in intermittent claudication: a controlled cross-over study.

The effect of a new physical treatment modality, Vacusac, was tested on a group of patients with stable intermittent claudication. Twenty-two patients with a median age of 65 years and a median duration of intermittent claudication of 5 years were randomized to either active or placebo treatments. Seventeen patients completed the study. The effect of treatment was quantified by measurements of systemic and peripheral systolic blood pressures and by measurements of the pain-free and the maximal walking distance on a treadmill. The ankle pressure index (ankle systolic pressure/arm systolic pressure) and toe pressure index (toe systolic pressure/arm systolic pressure) were calculated. After 25 active treatments, administered over a period of 2 months, the patients allocated to this group attained a significant increase in the pain-free walking distance from 54 m (24-107 m) to 99 m (30-420 m) (P less than 0.05) and in the maximal walking distance from 99 m (36-182 m) to 185 m (68-591 m) (P less than 0.05). The patient group receiving 25 placebo treatments did not show any significant changes in either the pain-free or the maximal walking distance. This group then received 25 active treatments over a period of 2 months. This active treatment resulted in a significant increase in the pain-free walking distance from 51 m (14-100 m) to 86 m (18-1000 m) (P less than 0.05) and in the maximal walking distance from 98 m (40-199 m) to 175 m (51-1000 m) (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Reliability of impedance cardiography in measuring central haemodynamics.

The purpose of the study described here was to investigate the reliability of impedance cardiography (IC) in measuring cardiac output (CO) and central blood volume. Absolute values and changes in these variables obtained by impedance cardiography and by isotope- or thermodilution techniques were compared. The reproducibility of IC within the same day was compared with that of isotope dilution and the reproducibility in IC from day to day was derived. Finally, the effects of the readings of impedance tracings by different observers were quantified. The results are based on 270 measurements in 37 healthy subjects and in 25 unmedicated patients with ischaemic heart disease. We obtained significant correlations between absolute values (y = 0.68x + 1.48) and changes (y = 1.00x + 0.0003) in CO measured by IC and isotope- or thermodilution. IC significantly overestimated absolute values of CO (P less than 0.001). We found a qualitative but no quantitative correlation between thoracic fluid volume measured by IC and central blood volume measured by isotope dilution. IC was highly reproducible both when studies were repeated within the same day (SD on differences in CO = 0.36 1 min-1 for IC; SD on differences in CO = 0.30 1 min-1 for isotope dilution) and on different days (SD on differences in CO = 0.45 1 min-1). A low intra-observer variability was found (SD on differences in CO = 0.12 1 min-1). We conclude that impedance cardiography is reliable in measuring changes in cardiac output and thus suitable for repeated measurements in studies on the haemodynamic effects of physiological or pharmacological intervention. Impedance cardiography is sufficiently reliable for comparison of absolute values of CO between different groups of patients. We cannot recommend impedance cardiography for quantitative studies of central blood volume.

Blood Volume↗
PubMed1991

Central haemodynamics in patients with severe postural hypotension.

Central haemodynamics in the supine and head-up tilted positions were studied in 24 patients with severe postural hypotension with and without supine hypertension. Results were compared with those obtained in eight normotensive and eight untreated hypertensive controls. In the supine position the patients had higher vascular resistances, lower stroke volumes and longer left ventricular ejection time indexes compared to controls, whereas left ventricular ejection fractions did not differ significantly. The patients with supine hypertension had significantly higher vascular resistance compared to those with supine normotension. The highest supine blood pressure levels were found in patients with multiple system atrophy. During tilt, vascular resistance and heart rates were increased and stroke volumes and left ventricular ejection time indexes were decreased in the controls. The patients were unable to increase their vascular resistance, but increased their heart rate and decreased their left ventricular ejection time indexes to a degree similar to the controls. The reductions in stroke volume were smaller in the patients compared to the controls. Changes in haemodynamics in response to head-up tilting did not differ significantly between patients with supine hypertension and supine normotension. It is concluded that patients with postural hypotension have higher supine vascular resistance and are unable to contract peripheral arteries and arterioles during head-up tilting. Contractility of the left ventricle is preserved and the baroreceptors are partially intact. Postural hypotensive patients with supine hypertension differ from those with supine normotension only with respect to supine vascular resistances.

Adult↗
PubMed1990

Haemodynamics in postural hypotension--effects of the beta-adrenoceptor partial agonist xamoterol, and pindolol.

Beta-andrenoceptor agents have been used in the treatment of postural hypotension and agonist activity found to be important. The effects of xamoterol and pindolol on standing haemodynamics were compared in this study. Xamoterol was found to be of significant benefit, but pindolol was ineffective. Xamoterol may therefore be useful in the treatment of postural hypotension.

Adrenergic beta-Agonists↗
PubMed1990

Post-exercise platelet activation--aggregation and release in relation to dynamic exercise.

Relatively scarce information is found on the period immediately following physical stress, with special reference to human platelet activity. This, in connection with earlier observations of an increase in platelet release products and hyperaggregability following surgical stress, has initiated the present study. We studied platelet function in eight healthy non-mediated volunteers during and 1 h after cycle exercise of submaximal intensity. ADP-induced platelet aggregability was enhanced in the last minute of exercise followed by a decreased aggregability 1 h after. Adrenaline-induced platelet aggregation showed the same attenuation after exercise but no change during work. The release products beta-thromboglobulin and serotonin in plasma showed significant increases after exercise. This is taken as evidence of an enhanced platelet activity following exercise. A normal stress-response, measured as increase in cyclic AMP in plasma, was observed. In conclusion, platelets are activated following moderate exercise and it seems valid to include the post-exercise period in future studies.

Adenosine Diphosphate↗
PubMed1990

A comparison of systolic time intervals measured by impedance cardiography and carotid pulse tracing.

The purpose of this study was to compare the systolic time intervals (STI) obtained by impedance cardiography and by the conventional carotid technique. This comparison was done with respect to: 1) correlations between variables obtained by the two methods, 2) ability to reflect drug-induced changes, 3) reliability in terms of reproducibility and 4) heart rate dependency of the variables measured. The study included 25 unmedicated patients with ischaemic heart disease and 36 healthy subjects. We obtained significant correlations between STI-variables measured by the two methods (p less than 0.001) and found that left ventricular ejection times were longer when determined by the carotid technique (p less than 0.01). We found a significant correlation between drug-induced changes in STI-variables measured by the two methods (p less than 0.001). Both methods had a high degree of reproducibility and this parameter was significantly better within the same day, when impedance cardiography was used (p less than 0.01). The error due to the reading of STI-tracings obtained by impedance cardiography was very small when performed by the same observer. We found the pre-ejection period to be independent upon heart rate, while the left ventricular ejection time depended upon this parameter. We conclude that impedance cardiography and carotid technique differ with respect to the measurement of left ventricular ejection times, but not with respect to the measurement of other STI-variables. We furthermore conclude that both methods are reliable, but we recommend the use of impedance cardiography because it is easier to apply, it may be more precise and it can be used for simultaneous measurements of other haemodynamic variables.

Cardiac Output↗
PubMed1989

Forearm oxygen uptake during maximal forearm dynamic exercise.

This study was undertaken in an attempt to determine the maximal oxygen uptake in a small muscle group by measuring directly the oxygen expenditure of the forearm. Five healthy medical students volunteered. The subjects' maximal forearm work capacity was determined on a spring-loaded hand ergometer. Exercise was continued until exhaustion by pain or fatigue. Two weeks later intra-arterial and intravenous catheters were placed in the dominant arm. Blood samples for measurement of oxygen concentration were collected via the catheters. Forearm blood flow was measured by means of the indicator dilution technique. Oxygen uptake was determined according to the Fick principle. The forearm oxygen uptake attained at maximal work loads was a mean of 201 (SD +/- 56) mumol.min-1.100 ml-1. It was impossible at maximal exercise to discern a plateau of the oxygen uptake curve in relation to work output. It is suggested that a plateau in the oxygen uptake curve is not a useful criterion for maximal oxygen uptake in a small muscle group. Skeletal muscle may have an unused capacity for oxygen consumption even at maximal exercise intensity where muscle work cannot be continued due to muscle pain and fatigue.

Adult↗
PubMed1989

Plasma concentrations of adrenaline, noradrenaline and dopamine during forearm dynamic exercise.

In six healthy volunteers plasma concentrations of adrenaline, noradrenaline and dopamine were measured at rest and during dynamic forearm exercise at submaximal and maximal intensities. Arterial and venous concentrations of adrenaline and noradrenaline increased with forearm exercise at all workloads. Dopamine concentrations did not change. The increases in adrenaline and noradrenaline were almost linearly related to the increase in heart rate with no levelling off at maximal exercise intensities. It is concluded that dynamic exercise with the forearm muscle group causes a small but significant activation of the sympatho-adrenal system as reflected by increases in plasma concentrations of adrenaline and noradrenaline.

Adult↗
PubMed1989

Disposition kinetics of disopyramide in human healthy volunteers described by an open three compartment model.

Disposition kinetics of disopyramide was examined in an open randomised cross-over study in 8 healthy volunteers. Disopyramide was randomly administered as a single bolus injection (150 mg) over a period of 5 min. and as an infusion (28.2) mg/h to steady state. Disposition kinetics of disopyramide were most precisely described by an open three compartment model according to Akaike's information criteria. Significant positive correlations (0.909 +/- 0.04, P less than 0.05 (injection study); 0.787 +/- 0.11, P less than 0.05 (infusion study] were observed between total serum concentrations of disopyramide and renal clearance while no significant correlation could be demonstrated between free serum concentrations and renal clearance. This implies a constant value of unbound renal clearance. The results are consistent with non linear kinetics (mainly caused by the variable free fraction of the drug), when based on total serum concentrations. The disposition of unbound disopyramide, however seems to be linear (i.e. the kinetic parameters are independent of dose) in the bolus injection study. Total elimination clearance (free and total), volume of distribution and elimination half-life were significantly higher in the steady state experiment than in the bolus injection study.

Adult↗
PubMed1988

Effects of acute hypoxia and CO2 inhalation on systemic and peripheral oxygen uptake and circulatory responses during moderate exercise.

The effect of acute hypoxia and CO2 inhalation on leg blood flow (LBF), on leg vascular resistance (LVR) and on oxygen supply to and oxygen consumption in the exercising leg was studied in nine healthy male subjects during moderate one-leg exercise. Each subject exercised for 20 min on a cycle ergometer in four different conditions: normoxia, normoxia + 2% CO2, hypoxia corresponding to an altitude of 4000 m above sea level, and hypoxia + 1.2% CO2. Gas exchange, heart rate (HR), arterial blood pressure, and LBF were measured, and arterial and venous blood samples were analysed for PCO2, PO2, oxygen saturation, haematocrit and haemoglobin concentration. Systemic oxygen consumption was 1.83 l.min-1 (1.48-2.59) and was not affected by hypoxia or CO2 inhalation in hypoxia. HR was unaffected by CO2, but increased from 136 beat.min-1 (111-141) in normoxia to 155 (139-169) in hypoxia. LBF was 6.5 l.min-1 (5.4-7.6) in normoxia and increased significantly in hypoxia to 8.4 (5.9-10.1). LVR decreased significantly from 2.23 kPa.l-1.min (1.89-2.99) in normoxia to 1.89 (1.53-2.52) in hypoxia. The increase in LBF from normoxia to hypoxia correlated significantly with the decrease in LVR. When CO2 was added in hypoxia a significant correlation was also found between the decrease in LBF and the increase in LVR. In normoxia, the addition of CO2 caused a significant increase in mean blood pressure. Oxygen consumption in the exercising leg (leg VO2) in normoxia was 0.97 l.min-1 (0.72-1.10), and was unaffected by hypoxia and CO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Effects of three beta-blockers with different pharmacodynamic properties on platelet aggregation and platelet and plasma cyclic AMP.

The effects of three different types of beta-adrenoceptor blocking agents on platelet aggregation and on platelet and plasma cyclic AMP content have been studied in 14 patients with mild hypertension given each drug in turn for two weeks. The drugs were a non-selective blocking agent with high intrinsic sympathomimetic activity, pindolol, the nonspecific blocking agent propranolol, and the beta 1-selective metoprolol. The threshold values of ADP and adrenaline for irreversible platelet aggregation were significantly higher for pindolol and metoprolol than for propranolol. The cyclic AMP content of platelets was higher during pindolol and metoprolol than during propranolol treatment. Pindolol produced a substantial increase in plasma cyclic AMP relative to the other two drugs. Thus, platelet aggregation and cyclic AMP formation are influenced by beta-adrenoceptor blockade in proportion to intrinsic sympathomimetic activity and affinity for different beta-adrenoceptor subtypes.

Adenosine Diphosphate↗
PubMed1988

The effect of exercise on platelet beta-adrenoceptor function and platelet aggregation in healthy human volunteers.

UNLABELLED: Plasma levels of adrenaline and noradrenaline, platelet cyclic-AMP (cAMP) content, platelet aggregation, platelet release of beta-thromboglobulin, and platelet factor 4 and serum content of thromboxane B2(TXB2) and 6-keto-PGF1 alpha were measured in 12 healthy male volunteers (age 38-72, mean 54.2 years) who were tested at rest and immediately after five min light cycle exercise. The plasma levels of adrenaline and noradrenaline increased significantly after exercise (P less than 0.01). The platelet cAMP level was not changed by exercise. The functional capacity of platelet beta-adrenoceptors, determined as cAMP production after beta-adrenoceptor stimulation in vitro, decreased highly significantly after exercise in all 12 volunteers (P less than 0.01). No alteration was observed in platelet aggregation induced by adrenaline or in platelet release of beta-thromboglobulin or platelet factor 4. No change was observed in the serum levels of TXB2 and 6-keto-PGF1 alpha. IN CONCLUSION: light cycle exercise results in a decreased functional capacity of platelet beta-adrenoceptors, but has no effect on platelet aggregation or platelet release. This might indicate a concomitant and equal decreased functional capacity of platelet alpha-adrenoceptors.

Adult↗
PubMed1988

Long term haemodynamic effects of pinacidil and hydralazine in arterial hypertension.

Eight patients with a diastolic blood pressure greater than or equal to 100mm Hg when treated with a diuretic and a beta-blocker participated in a randomised crossover study comparing the haemodynamic effects of adjunctive therapy with pinacidil or hydralazine. The vasodilator dose was increased until the diastolic blood pressure was less than 90mm Hg or the maximum dosage, hydralazine 100mg twice daily, or pinacidil 50mg twice daily, was reached. Treatment continued for 3 to 6 months and a haemodynamic study was performed. After washout, the patients received the alternative treatment. In the upright position, during supine rest and during isometric as well as dynamic exercise, pinacidil lowered blood pressure more effectively than hydralazine. No differences between the 2 treatments were found in heart rate, stroke index, cardiac index, end systolic wall stress or glomerular filtration rate. Pulmonary mean and wedge pressure were lower during treatment with pinacidil. Forearm blood flow was higher and forearm vascular resistance lower during treatment with pinacidil. Cardiac contractility, judged from the systolic time interval ratio PEP: LVET, was lower during treatment with pinacidil compared with hydralazine. The median daily dose of pinacidil was 50mg and that of hydralazine 200mg. It was also noted that during long term treatment, pinacidil seemed more effective in reducing blood pressure than hydralazine.

Antihypertensive Agents↗
PubMed1988

Prenalterol in severe congestive heart failure. I. The immediate haemodynamic effects as compared to nitroglycerine.

The immediate haemodynamic effects of prenalterol and nitroglycerine were examined in 15 patients, with severe chronic heart failure. Prenalterol was given intravenously in increasing doses of 2, 4, and 8 mg. Cardiac index increased significantly by 16%, 24%, and 32%, respectively. Heart rate increased by 16%, 19%, and 24%. Stroke volume index, systemic artery pressure, pulmonary artery pressure, and right atrial pressure did not change. Prenalterol reduced systemic vascular resistance by 15%, 17%, and 24%, respectively. Forearm blood flow and forearm vascular resistance was unchanged. Cardiac index and heart rate were not changed by 0.5 mg nitroglycerine, administered sublingually. Systolic and diastolic blood pressure were on average reduced by 14% and 12%, respectively. Systolic and diastolic pulmonary artery pressure and right atrial pressure were similarly reduced by 17%, 31%, and 39%, respectively. Nitroglycerine lowered calculated systemic vascular resistance by 11%, whereas forearm blood flow and forearm vascular resistance was unchanged. The conclusion is that prenalterol acutely increased cardiac index and improved haemodynamics in 14 out of 15 patients, mainly due to an increased heart rate. Nitroglycerine did not change cardiac index in the same group of patients.

Aged↗
PubMed1987

Immediate haemodynamic effects of a novel partial agonist, beta 1-adrenoceptor blocking drug ICI 141,292 after intravenous administration to healthy young volunteers and patients with ischaemic heart disease.

ICI 141,292 is a new beta 1-adrenoceptor blocking drug. The beta 1-adrenoceptor antagonistic effect of ICI 141,292 was examined in a double-blind, randomised crossover study in eight healthy young volunteers and compared with atenolol. Three doses of ICI 141,292 (1, 2 and 4 mg) and atenolol 5 mg were administered intravenously. The attenuation in exercise induced tachycardia varied between 16.0 and 21.2% (P less than 0.01). A significant reduction in blood pressure could be demonstrated following all three doses of ICI 141,292 and atenolol during exercise. At rest in the sitting position HR decreased approximately 8% following all three doses of ICI 141,292 and 14.9% after atenolol 5 mg. No changes in blood pressure were observed under resting conditions after any of the drugs. In six patients with ischaemic heart disease the intrinsic sympathomimetic activity following intravenous administration of four sequential doses (0.5, 0.5, 1.0 and 2.0 mg) of ICI 141,292 was examined. HR decreased 7% (P less than 0.05) following ICI 141,292 1 mg with no further decrease following the succeeding doses. Cardiac output decreased 5.2% (P less than 0.05) following a cumulative dose of 4 mg. No significant changes were observed in mean arterial blood pressure, stroke volume or total peripheral resistance whereas an increase in supine resting mean pulmonary arterial pressure of 3.4 mm Hg (P less than 0.05) could be demonstrated. ICI 141,292 seems to be a potent (at least five times as potent as atenolol) beta 1-adrenoceptor blocking agent possessing moderate intrinsic sympathomimetic activity.

Adrenergic beta-Antagonists↗