Comparison of adrenergic beta-receptor antagonists in angina pectoris

The symptomatic, electrocardiographic, and circulatory effects of intravenous and oral preparations of propranolol, oxprenolol, and practolol were compared in 16 patients with uncomplicated angina pectoris precipitated by exertion. The method of study included treadmill exercise, double-blind assessment, single-blind analysis, with placebo control and randomized serial comparison of each drug in each patient. The doses used were selected to give the same near-maximum suppression of the heart rate response to exercise. The symptomatic, electrocardiographic, and circulatory response of each patient to both preparations of each of the three drugs was similar. Exercise tolerance was increased in two-thirds, unchanged in one-sixth, and significantly worsened in one-sixth of the studies. Electrocardiographic evidence of myocardial ischaemia was conspicuously reduced by all three drugs in most studies irrespective of their symptomatic effects. Though the exclusive choice of patients, the single dose design of the trial, and the treadmill method of assessment limit the general application of these results, they do clearly indicate that in doses that induce equal suppression of the exercise heart rate these three drugs have similar distinct anti-anginal activity. Their ancillary pharmacological properties are probably of little importance in this respect. Equally, the similarity in the symptomatic, circulatory, and electrocardiographic response to the intravenous and oral preparations suggests that metabolic breakdown products are probably of therapeutic importance only in so far as they antagonize beta-receptor activity.

The multiple-cluster mutation complex in mutagenesis with higher plants

After treatment of dry and pre-soaked seeds of barley with gamma-rays, EMS, NEU and EI, the frequency of multiple mutations (multimutations) was higher with EMS and NEU treatment, while cluster mutations appeared in greater numbers following treatment with gamma rays and NEU. Pre-soaking the seeds led to a reduction in the frequency of total mutations, cluster mutations and multimutations. This has been explained as a result of the application of lower doses and the induction of mutations at a relatively later stage in ontogenetic development in the case of pre-soaked seeds.Some new mutation types in barley have been described and some of the old types have been given names representing the mutation characters more precisely.The compound mutation frequency of different seedling mutation types, when taken separately, was found to be independent of the mutagen employed and the stage of treatment. The size of mutated chimeras in M 1 plants, as indicated by the segregation ratio of mutants in M 2, was largest in albina, xantha, chlorina, albina-tigrina, chl-terminalis and eceriferum, and lowest in viridis, viridoalbina etc. This could be expected if the unstable premutations induced by mutagenic treatment are resolved into mutations at different intervals after their initiation, or it can be explained by the induction of dominant mutations, or lethal changes together with visible mutations.

Comparison of adrenergic beta-blocking drugs in angina pectoris

The symptomatic, electrocardiographic, and haemodynamic effects of two adrenergic beta-blocking drugs, oxprenolol and propranolol, have been compared in equipotent intravenous doses in six patients with uncomplicated angina pectoris during treadmill exercise. The method of comparison included double-blind assessment and analysis with placebo control and randomized serial comparison in each patient. Both drugs produced an equal amelioration in symptoms in most of the patients. This was closely correlated with improvement in the electrocardiographic changes and a significant reduction in the exercising heart rate and systemic arterial pressure. This method of double-blind combined subjective and objective assessment carries distinct advantages in the comparative assessment of drug treatments in angina pectoris.

Insulin secretion in heart failure

Insulin secretion tests were carried out before and after treatment in patients with severe congestive heart failure. Before treatment the plasma insulin level and the insulin secretion response to intravenous tolbutamide were significantly reduced in all patients. In patients who made a good clinical recovery the plasma insulin level and the insulin secretion response were significantly improved. Patients who had a poor response to medical treatment showed little improvement in their insulin secretion test. This suppression of insulin secretion is probably due to the reduced blood flow to the pancreas together with a high level of circulating catecholamines.