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Biomedical subjects

J Trap-Jensen

Publications and source records attributed to J Trap-Jensen.

At least 55 records · Page 3Linked to original sources
PubMed1985

99mTc-DTPA gamma-camera renography: normal values and rapid determination of single-kidney glomerular filtration rate.

A method for 99mTc-diethylenetriaminepentaacetate (DTPA) gamma-camera renography is presented. From each renogram, an uptake index (UI) proportional to the single-kidney glomerular filtration rate (SKGFR) is defined. If the proportionality factor between UI and SKGFR is the same in all patients, UI can be used as an accurate measure of SKGFR. In order to test this, 99mTc-DTPA renography was performed in 101 patients with glomerular filtration rates (GFR) varying between 4 and 172 ml/min. The sum of the right- and left-kidney UIs correlated well with the total GFR calculated from the simultaneously measured plasma clearance of 99mTc-DTPA after a single injection. The correlation coefficient was 0.97. The method was tested in a prospective study of 57 patients. The total GFR estimated from the renograms was not significantly different from the GFR calculated from the plasma clearance of 99mTc-DTPA. The coefficient of variation--a combination of inaccuracy and imprecision in the estimates as well as in the reference values-was 11.8% at a GFR of 100 ml/min. It is concluded that, in adults, the SKGFR can be calculated as part of the clinical routine from 99mTc-DTPA gamma-camera renography without determining the injected dose or collecting urine or blood samples. Normal values for some parameters of the renogram obtained in 25 normal subjects are given.

Adult↗
PubMed1985

Immediate central and regional haemodynamic effects of a new beta 1-adrenergic stimulating drug, xamoterol (Corwin) in healthy volunteers.

Dose-response curves for heart rate, arterial blood pressure, cardiac output, total peripheral resistance, systolic time intervals, forearm blood flow and forearm vascular resistance were obtained after i.v. administration of seven logarithmically increasing doses of xamoterol to 8 healthy volunteers. The total cumulative dose was 0.2 mg/kg b.w. At rest after the seventh dose of xamoterol heart rate, systolic blood, pressure, cardiac output and forearm blood flow were increased by 10%, 20%, 23% and 41%, respectively. Diastolic blood pressure was unchanged. Forearm vascular resistance was reduced by 21% and total peripheral resistance by 10%. Systolic time intervals were reduced: total electromechanical systole index (QS2I), left ventricular ejection time index (LVETI), pre ejection period index (PEPI) and PEP/LVET ratio by 4%, 2%, 12% and 14%, respectively. No side-effects were observed. During upright exercise after the seventh dose of xamoterol heart rate was reduced by 11% and systolic BP by 6%. Diastolic blood pressure was unchanged. Thus xamoterol increased the contractility of the heart with only a small increase in heart rate, increased systolic blood pressure and caused vasodilatation in resting skeletal muscle. During exercise the reduction in heart rate and blood pressure suggests beta-adrenoceptor blocking activity of the drug.

Adrenergic beta-Agonists↗
PubMed1985

Immediate central hemodynamic effects of five different beta-adrenoceptor-blocking agents, acebutolol, atenolol, pindolol, practolol, and propranolol, in patients with ischemic heart disease.

The hemodynamic effects of acebutolol were studied in six patients with ischemic heart disease. The changes in heart rate, cardiac output, and arterial blood pressure were determined after intravenous administration of six increasing doses of acebutolol to a cumulative dose of 0.64 mg/kg. After the sixth dose of acebutolol, cardiac output and heart rate were reduced 15% and 8%, respectively. Pulmonary artery pressure was increased by 4 mm Hg. Arterial blood pressure was not changed significantly. The effects of graded doses of acebutolol on heart rate and cardiac output were compared with earlier obtained results after atenolol (0.19 mg/kg), pindolol (0.025 mg/kg), practolol (0.64 mg/kg), and propranolol (0.19 mg/kg). The effects of increasing doses of acebutolol and practolol were very similar and significantly different from the effects of the other three drugs in spite having been administered at equipotent doses. The hemodynamic effects of acebutolol support the hypothesis that the hemodynamic response to beta-adrenoceptor antagonist drugs at rest is determined primarily by the degree of intrinsic sympathomimetic activity, whereas beta-1 selectivity does not modify the central hemodynamic response.

Acebutolol↗
PubMed1985

Acute hemodynamic effects of pinacidil and hydralazine in essential hypertension.

In a double-blind, randomized, crossover study, the effects of intravenous pinacidil, 0.2 mg/kg, were compared with those of hydralazine, 0.3 mg/kg, before and after beta-adrenoceptor blockade in six subjects with hypertension. Both drugs equally reduced total peripheral resistance by about 40%. Pinacidil reduced mean blood pressure by an average of 30 mm Hg, while the reduction after hydralazine was 10 mm Hg. The difference in antihypertensive effect resulted from greater increases in heart rate, cardiac contractility (systolic time intervals), and cardiac index (thermodilution) after hydralazine. These effects after hydralazine could not be fully abolished by beta-blockade, as could the effects after pinacidil. Pinacidil decreased pulmonary blood pressure, whereas there was a slight rise in pulmonary blood pressure after hydralazine. Forearm blood flow (venous occlusion strain gauge plethysmography) increased equally after both drugs; thus pinacidil decreased forearm vascular resistance more than hydralazine did. Serum concentrations of both drugs were within the therapeutic range and correlated with the fall in mean blood pressure. Five subjects complained of side effects after hydralazine, but none were reported after pinacidil. Hydralazine increased myocardial oxygen consumption (as estimated from the rate-pressure product) by 35%; there was no change after pinacidil. It is suggested that hydralazine has direct cardiostimulatory effects that limit its antihypertensive effectiveness. These effects increase myocardial oxygen consumption and may be responsible for the common and sometimes severe cardiovascular side effects of hydralazine.

Adrenergic beta-Antagonists↗
PubMed1985

Haemodynamic effects of single-dose felodipine in normal man.

The haemodynamic effects of an oral solution of 15 mg felodipine were studied in 8 healthy males. Maximal plasma concentrations of felodipine were seen 30 to 40 minutes after administration, when significant decreases in diastolic and mean blood pressures were noted. Heart rate increased maximally by 45% after 30 minutes, accompanied by a 57% increase in cardiac output and 175% increase in forearm blood flow. Total peripheral resistance decreased by 40% and forearm vascular resistance by 66%. Apparent hepatic blood flow was unchanged.

Adult↗
PubMed1984

Simultaneous measurement of renal clearance and plasma clearance of 99mTc-labelled diethylenetriaminepenta-acetate, 51Cr-labelled ethylenediaminetetra-acetate and inulin in man.

The present investigation was undertaken to study the kinetics of 99mTc-labelled diethylenetriaminepenta-acetate (DTPA) as compared with inulin and 51Cr-labelled ethylenediaminetetra-acetate (EDTA). Twenty patients with various degrees of decreased renal function were studied. The renal clearance, plasma clearance and volume of distribution of all three tracers were measured after a simultaneous single injection. The average renal clearance ratio 99mTc-DTPA to inulin was 0.97; the average renal clearance ratio 99mTc-DTPA to 51Cr-EDTA was 1.02. In all patients the plasma clearance of inulin exceeded that of 99mTc-DTPA. No difference was seen between the plasma clearance of 99mTc-DTPA and 51Cr-EDTA. The plasma clearance of all three tracers overestimated the simultaneously measured renal clearance; on average this was, for 99mTc-DTPA 5.7 ml/min, for 51Cr-EDTA 6.0 ml/min and for inulin 8.1 ml/min. The plasma clearance of 99mTc-DTPA correlated well with the renal clearance of inulin, but overestimated this by 3.5 ml/min on average. The volume of distribution of inulin was less than that of 99mTc-DTPA and 51Cr-EDTA. No difference was seen between the volume of distribution of 99mTc-DTPA and 51Cr-EDTA. It is concluded that the difference in the kinetics of 99mTc-DTPA and 51Cr-EDTA in patients with decreased renal function was small and without clinical relevance.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1983

Pinacidil, a new vasodilator: pharmacokinetics and pharmacodynamics of a new retarded release tablet in essential hypertension.

In an open study increasing doses of a retarded tablet formulation of pinacidil were given twice daily for four weeks to 9 patients with untreated essential hypertension (WHO I-II). In all patients a decrease in diastolic blood pressure to below 100 mmHg, or a fall exceeding 15 mmHg, was obtained 2 h after tablet intake (p less than 0.02), but in only two patients was the effect maintained after 10 hours (n.s.). At a mean serum concentration of 100 ng/ml 2 h after pinacidil 30 mg, the mean blood pressure had decreased by 14 and 12.7 mmHg in the supine and erect positions, respectively (p less than 0.05). In contrast, mean blood pressure 10 h after the same dose was unchanged, when the mean serum concentration was 47.5 ng/ml. No change in heart rate was observed. Pharmacokinetic and pharmacodynamic investigations showed a tendency towards a more gradual and longer lasting antihypertensive effect and serum concentration-time curve after the retarded tablet than the previous tablet. Pinacidil 40 mg in the retarded tablet reduced mean blood pressure and increased heart rate for at least 8 h. There was a linear correlation between the serum concentration and the change in mean blood pressure, and between the changes in mean blood pressure and in heart rate. There was no indication of tachyphylaxis. A serum level of 50 ng/ml of pinacidil appeared to be the minimal effective concentration. The side effect consisted of fluid retention, and the body weight increased by 1.0 kg (p less than 0.05); four patients complained of oedema.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Haemodynamic and metabolic effects of alpha-adrenoceptor blockade with phentolamine at rest and during forearm exercise.

The pre- and post-junctional alpha-adrenoceptor blocking agent, phentolamine, was given by intravenous infusion to eight healthy volunteers during rest, forearm exercise and post-exercise. Phentolamine produced a sustained increase in heart rate. The diastolic blood pressure decreased slightly whereas systolic and mean blood pressures remained unchanged. Phentolamine caused a marked increase in the forearm blood flow and a decrease in vascular resistance at rest and post-exercise, but did not influence the blood flow or vascular resistance in the exercising forearm. There was a small increase in arterial blood glucose concentration, and a decrease in blood alanine concentration during drug infusion. Blood lactate was not affected by phentolamine. The arterial concentrations of free fatty acids and glycerol increased, and the concentration of triglycerides decreased during phentolamine infusion. Forearm exchange of glucose, lactate, alanine, glycerol, free fatty acids, triglycerides and forearm oxygen consumption were not changed significantly. These findings corroborate the concept that alpha-adrenoceptor induced vasoconstriction plays a subordinate role in exercising skeletal muscle. All of the metabolic findings might be explained as secondary to an increased noradrenaline release during phentolamine infusion.

Adult↗
PubMed1983

Skin perfusion pressure measured by isotope washout in legs with arterial occlusive disease. Evaluation of different tracers, comparison to segmental systolic pressure, angiography and transcutaneous oxygen tension and variations during changes in systemic blood pressure.

The skin perfusion pressure (SPP) measured as the isotope washout cessation external pressure is valuable in selection of major amputation level. Five methodological investigations important to clinical use were carried out: (1) In five normal legs and 10 legs with arterial occlusive disease (AOD), 131I- -antipyrine (131I- -a.p.) was compared to Na(131I-) and 99Tcm-pertechnetate (99Tcm). The average SPP by 131I- -a.p. and by 131I- were approximately equal, 57.0 mmHg (range 18-93) compared to 56.3 mmHg (range 13-88) (P greater than 0.1). The average SPP by 99Tcm was just slightly higher, 60.3 mmHg (range 18-98) (P less than 0.02). The average washout constant for the three different tracers were approximately equal and correlated statistically significant with the SPP; (2) In 59 legs with AOD, segmental SPP was compared to segmental systolic blood pressures on the thigh, calf, ankle and first digit (strain gauge technique). The two different methods correlated statistically significant at all four levels, but the systolic blood pressures were higher than the SPP in particular in diabetic legs; (3) Angiograms in 35 legs with AOD showed that the SPP on the ankle was only consistently decreased in legs with arterial occlusions at two levels or more; (4) In 47 legs with AOD, the SPP on the calf or on the thigh was compared with transcutaneously measured pO2. The two different methods correlated statistically significant, but the scatter was great; (5) During induced variations in systemic blood pressure in seven patients (12 legs with AOD), the segmental SPP and the segmental systolic blood pressure were found on average to vary in proportion with intra-arterial mean and systolic pressure respectively; however, this proportional relationship was not valid for the individual leg. It is concluded that 99Tcm is as suitable as the 131I- -labelled tracers in estimating the SPP. The SPP is significantly correlated to skin blood flow, to systolic blood pressure, to tc pO2 and to angiographic findings. Correction of SPP for systemic blood pressure changes can be made in proportion with the measured variations in systemic mean blood pressure, but only for groups of patients.

Angiography↗
PubMed1982

Haemodynamic and metabolic effects of diazoxide during rest and forearm exercise.

The immediate haemodynamic and metabolic effects of acute dose of diazoxide 300 mg i.v. were studied in six healthy subjects at rest and during dynamic forearm exercise. Control periods of rest, exercise and recovery were compared with corresponding periods after drug administration. Resting forearm blood flow was almost doubled after diazoxide, and during forearm exercise it increased by about 24%. Systolic blood pressure did not change significantly, but diastolic blood pressure was moderately decreased (5-10 mm Hg). The mean heart rate increased from 57 to 92 beats/min immediately after diazoxide administration and remained about 20% higher throughout the study. There was a sustained increase in arterial blood glucose of almost 1 mmol/l. The arterial concentration of free fatty acids increased transiently just after diazoxide and then returned to the pre-drug level. The arterial concentration of triglycerides after diazoxide was decreased by about 15% throughout the study. Arterial blood lactate remained unchanged. Forearm uptake of oxygen and glucose tended to increase during the exercise and recovery periods, whereas lactate release remained unchanged.

Adult↗
PubMed1982

Effects of propranolol and pindolol on plasma lignocaine clearance in man.

1 Steady state concentrations and clearance of lignocaine were determine in eight healthy volunteers during 360 min continuous lignocaine infusion (2 mg/min). Before the infusion propranolol (0.18 mg/kg i.v.), pindolol (0.023 mg/kg i.v.) or placebo were administered in a random double-blind, cross over design. 2 During the infusion of lignocaine heart rate, cardiac output and arterial blood pressure were measured every 60 min. 3 Propranolol decreased heart rate and cardiac output significantly by 10--20%, while pindolol or lignocaine did not change cardiac output or heart rate significantly. None of the drugs changed the arterial blood pressure. 4 Propranolol pretreatment decreased lignocaine significantly by 14.7% and the steady state concentration was increased by 22.5%. Pindolol produced no significant change in steady state concentration or clearance of lignocaine.

Adult↗
PubMed1982

Beta-adrenoceptor blockade and psychic stress in man. A comparison of the acute effects of labetalol, metoprolol, pindolol and propranolol on plasma levels of adrenaline and noradrenaline.

1 A random double-blind study was performed in healthy volunteers. The immediate effects of three different beta-adrenoceptor blocking agents, metoprolol, pindolol and propranolol, on the plasma concentrations of adrenaline and noradrenaline were compared in a situation of pleasant psychic stimulation during a television-game of tennis. The immediate effects of labetalol in a group of patients with arterial hypertension were studied in a similar experimental situation. 2 During psychic stress the plasma concentration of noradrenaline rose significantly by 85% after placebo, by 95% after labetalol, by 63% after metoprolol and by 55% after propranolol. After pindolol the noradrenaline concentration remained unchanged. 3 During psychic stress the plasma concentration of adrenaline rose significantly by 135% after labetalol, by 110% after metoprolol and by 83% after propranolol. After pindolol and placebo the adrenaline concentration remained unchanged. 4 The present results are taken to indicate that the intrinsic sympathomimetic activity possessed by pindolol prevents the rise in plasma noradrenaline normally seen during psychic stress. It is suggested that beta-adrenoceptor blockers with strong intrinsic sympathomimetic effect reduce the release of catecholamines during psychic stress.

Adrenergic beta-Antagonists↗
PubMed1982

Stimulation of beta-adrenoceptors in the exercising human forearm.

In order to study the effects of local stimulation of beta-adrenoceptors on limb blood flow during exercise and on muscle metabolism, the non-selective beta-adrenoceptor agonist, isoprenaline, was infused intra-arterially into the forearm of six healthy, young subjects. Isoprenaline caused a marked increase in forearm blood flow not only at rest but also during dynamic forearm exercise. The forearm release of lactate increased considerably during drug infusion whereas glucose uptake decreased. The net uptake of free fatty acids during exercise decreased. There were no systemic effects of isoprenaline. These findings suggest that the resistance vessels are responsive to beta-adrenergic vasodilatation also during muscle exercise. The increase in blood flow through the exercising forearm may be secondary to an increased muscle metabolism. The increased lactate release from the exercising muscles indicates an increased muscle glycogen breakdown during beta-adrenoceptor stimulation.

Adult↗
PubMed1982

Central and regional circulatory adaptations to one-leg training.

Six young healthy male subjects performed submaximal and maximal exercise on bicycle ergometers with one leg and two legs before and after 8 wk of one-leg training with each of both legs. The following variables were measured during one- and two-leg exercise: oxygen uptake, heart rate, mean arterial blood pressure, cardiac output, leg blood flow, and iliac arteriovenous differences for oxygen and lactate. After training the maximal oxygen uptake during one- and two-leg exercise was increased by 19 and 11%, respectively. The corresponding cardiac outputs increased by 16 and 11%, respectively. During submaximal one-leg exercise, heart rate decreased by 11%, whereas a decrease of only 2% was seen during submaximal two-leg exercise. Mean blood pressure decreased by about 10 Torr in both types of exercise and during both submaximal and maximal exercise. Maximal leg blood flow increased only by 1.2 l/min during one-leg exercise. Leg blood flow and leg oxygen uptake were smaller during two-leg exercise than during one-leg exercise and more so after training. These findings indicate that one-leg exercise, compared with two-leg exercise, involves circulatory adaptations that respond differently to one-leg training. The findings further imply that oxygen supply to one large muscle group of exercising muscles may be limited by vasoconstriction when another large group of muscles is exercising simultaneously.

Adaptation, Physiological↗