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Biomedical subjects

J D Harry

Publications and source records attributed to J D Harry.

At least 37 records · Page 2Linked to original sources
PubMed1985

Experience with a Doppler technique to investigate the interaction of isoprenaline and various B-adrenoceptor blocking drugs on blood vessels in the lower limb.

A Doppler technique has been used in three separate studies to measure the changes induced by increasing infusion rates of isoprenaline on blood velocity, blood flow and diameters in the femoral and posterior tibial arteries of normal volunteers and to investigate the effects of various B-adrenoceptor antagonists on these changes. Heart rate and blood pressures were also recorded. Isoprenaline produced the expected changes in heart rates and blood pressures in the volunteers and changes induced in these responses by the B-adrenoceptor antagonist were as seen by previous workers. The only expected finding was that systolic blood pressure at the ankle was decreased compared to that in the arm which was increased. Isoprenaline produced reproducible dose-dependent increases in blood velocity, blood flow and diameters in the femoral artery, but little or no effects in the posterior tibial artery. These differences may reflect the difference in distribution of these arteries, the femoral to large muscular beds and the posterior tibial artery essentially to skin vascular beds. The different effects of the B-adrenoceptor blocking drugs with different actions on B1- and B2-adrenoceptors on the responses of the Doppler measurements to isoprenaline would support the differences in distribution of the femoral and posterior tibial arteries and allow a conclusion that the muscle vascular beds contain essentially B2-adrenoceptors with respect to stimulation by isoprenaline. The results obtained in three separate studies using the Doppler technique do suggest that this non-invasive technique may be of value in investigating the physiology, and/or pharmacology of the peripheral circulation in man.

Adrenergic beta-Antagonists↗
PubMed1984

The use of Doppler ultrasound techniques to study the effects of isoprenaline and beta-adrenoceptor blocking drugs on peripheral blood vessels in man.

A Doppler ultrasound technique has been used in six volunteers to determine the effects of intravenous isoprenaline on blood velocity and volume blood flow in the femoral artery and to investigate the effects of single oral doses of atenolol (50 mg) and propranolol (40 mg) on these effects and on heart rate changes. Isoprenaline increased the blood velocity and volume blood flow which was attenuated by propranolol and not by atenolol; the tachycardia of isoprenaline was inhibited by both drugs. The results show that the Doppler ultrasound measurements in the femoral artery can identify pharmacologically induced changes in peripheral blood vessels in the leg and warrants further investigation as a tool to study the pharmacology of peripheral blood vessels in man.

Adrenergic beta-Antagonists↗
PubMed1981

Relative activities of atenolol and metoprolol on the cardiovascular system of man.

The effects or oral atenolol (100 mg once/day) and metoprolol (100 mg once/day, 100 mg twice/day and 300 mg once/day) have been compared with placebo on the heart rate and systolic blood pressure responses to exercise in 5 healthy volunteers. The drugs were given for 5 days in a double blind randomised fashion with each volunteer receiving each dose of drug. Measurements were made after the first dose on day 1 and after 5 days of dosing. The results on both heart rate and systolic blood pressure showed that overall (over a 24 h period) after acute (day 1) or after chronic (5 days) dosing, atenolol 100 mg once/day, metoprolol 100 mg twice/day and 300 mg once/day, were equivalent as beta-adrenoceptor blocking doses. Thus milligram for milligram atenolol and metoprolol do not produce equivalent blockade on the cardiovascular system of man.

Adolescent↗
PubMed1980

A study of the effects of atenolol and propranolol on renal function in patients with essential hypertension.

1 The effects of propranolol and atenolol given in random order in a cross-over study to fifteen patients with essential hypertension have been studied. 2 Both drugs were effective in lowering blood pressure and side effects were not markedly different. 3 There was no change in exchangeable sodium or potassium or in total body potassium during treatment with either drug. 4 Ambulant plasma renin activity was reduced by both drugs but the fall in blood pressure was not related to initial plasma renin. 5 Despite equal mean reduction in blood pressure with the two drugs, creatinine clearance fell significantly only during treatment with propranolol. 6 These observations suggest that intra-renal beta 2-adrenoceptors may be of importance in the regulation of renal function.

Adult↗
PubMed1979

Dose response for blood pressure and degree of cardiac beta-blockade with atenolol.

The hypotensive effect of 25 mg, 50 mg, 75 mg, 100 mg and 0 mg of atenolol daily were compared in a double-blind within-patient study. The fall in blood pressure with 25 mg daily was not significantly different than with 100 mg. The dose response curve lies between 0 and 25 mg daily. Cardiac beta-blockade (measured by suppression of exercise tachycardia) was not maximal with 25 mg of atenolol daily. The dose response curves for beta-blockade and the hypotensive effect are not parallel.

Adult↗
PubMed1979

Effects of 4 beta-adrenoceptor blocking drugs on blood pressure and exercise heart rate in hypertension.

The effects of 4 beta-adrenoceptor blocking drugs on blood pressure and on exercise tachycardia were compared in a within-patient study of patients with uncomplicated essential hypertension. Twelve patients were treated with propranolol, practolol and atenolol and 7 of the same patients also received oxprenolol. Each patient received each drug separately, withdrawing each drug before starting the next, and each patient was titrated to the lowest attainable blood pressure and heart rate with each compound. All 4 drugs caused reductions in both systolic and diastolic blood pressure and in the heart rate induced by exercise. The maximum reduction by each drug in both systolic and diastolic blood pressure was the same. There were small but significant differences in the effects on heart rate between those drugs which had intrinsic sympathomimetic activity and those which did not have this property.

Adrenergic beta-Antagonists↗
PubMed1978

Comparison of atenolol with propranolol in the treatment of angina pectoris with special reference to once daily administration of atenolol.

Fourteen patients with angina pectoris completed a double blind trial of atenolol 25 mg, 50 mg, and 100 mg twice daily and propranolol 80 mg thrice daily. In comparison with placebo, all active treatments significantly reduced anginal attacks, consumption of glyceryl trinitrate, resting and exercise heart rate, resting and exercise systolic blood pressure, and significantly prolonged exercise time. There was no significant difference between the effects of propranolol and atenolol. Nine patients completed a further trial comparing atenolol given once or twice daily. Both regimens were effective and there was no significant difference between the reductions in anginal attacks, glyceryl trinitrate consumption, systolic blood pressure, or heart rate. Twenty-four-hour ambulatory electrocardiograms showed that atenolol consistently reduced heart rate throughout the 24-hour period whether given once or twice daily. Atenolol is a potent antianginal agent which, in most patients, is likely to be effective once daily.

Adult↗
PubMed1976

Evaluation of intrinsic sympathomimetic activity of beta-adrenoceptor blocking drugs in the treatment of patients with angina pectoris.

Beta-adrenoceptor blocking drugs with intrinsic sympathomimetic activity (ISA) may be less effective in the treatment of patients with angina pectoris than some others that lack this property. A review of 14 trials comparing beta-adrenoceptor blocking drug with ISA and those without ISA in angina pectoris has been made. The overall picture emerges from both acute and chronic studies using subjective and objective endpoints, that there is no striking difference in effectiveness between the two kinds of beta-adrenoceptor blocking drugs. The one exception is pindolol (a drug with ISA) which, at higher doses, has been shown to be consistently worse than propranolol (a drug without ISA). The reasons for the similarity between propranolol and other bets-blocking drugs with ISA in the trials cited are either that the trial design was defective (the trials were mainly fixed dose comparisons) or that the stimulant effects of those drugs with ISA is not of sufficient magnitude to make a difference. It is suggested that further carefully constructed clinical trials should be carried out before the second reason can be accepted.

Acute Disease↗
PubMed1974

The actions of a new beta-adrenoceptor blocking drug, ICI 66082, on the rabbit papillary muscle and on the dog heart.

1 The actions of 4-(2-hydroxy-3-isopropylaminopropoxy) phenyl acetamide (ICI 66082), a new beta-adrenoceptor blocking drug, on the twitch response of the isolated papillary muscle of the rabbit and on dP/dt max and free heart rate of a denervated dog heart preparation, are described.2 ICI 66082 (up to 1 mg/ml) did not produce any depression of the twitch response of the rabbit papillary muscle. ICI 66082 antagonized the action of isoprenaline on this preparation at a concentration of 0.01 mug/ml.3 ICI 66082 (0.5-1.0 mg/kg intravenously) reduced the control value of dP/dt max in four dog preparations by a mean value of 529 mmHg/s (s.e. mean +/- 139 mm Hg/s), with no significant change in free heart rate. Antagonism of the effect of isoprenaline on dP/dt max and on free heart rate was demonstrated with ICI 66082 (0.1 mg/kg).4 ICI 66082 (1.0-1.5 mg/kg) produced no significant changes in dP/dt max or in free heart rate in four dogs pretreated with reserpine. A significant reduction (16% of the control value) in dP/dt max was observed with ICI 66082 at a high dose of 40-50 mg/kg.5 It is concluded that ICI 66082 is a competitive antagonist against the actions of isoprenaline on cardiac muscle, has no negative inotropic action (unless the dose exceeds 40 mg/kg) and lacks intrinsic sympathomimetic activity.

Acetamides↗