Functional and metabolic effects of terbutaline and propranolol in fast- and slow-contracting skeletal muscle in vitro

The soleus, a slow-contracting, and the extensor digitorum longus (EDL), a fast-contracting skeletal muscle from guinea-pig were prepared for isometric recording of sub-tetanic contractions in vitro. The contents of adenosine-triphosphate (ATP) and creatinephosphate (CP) together with their metabolites and the contents of lactate, pyruvate and cyclic adenosine-monophosphate (c-AMP) in the muscles were determined. It was found that the energy and redox state of the isolated soleus and EDL muscles is very stable and does not significantly differ from the normal state in vivo. Moreover, there were no consistent changes in these variables after treatment with terbutaline (a β₂-adrenoceptor agonist) or propranolol or both. Thus, effects on energy metabolism do not seem to cause the changes in muscle contraction, characteristic for β-adrenoceptor stimulation. On the other hand, the functional effects were accompanied by elevation of the c-AMP level of the muscles.     

Release of adenosine from rat lung by antigen and compound 48/80

The mechanism by which theophylline inhibits anaphylactic constriction of the airways is not known (Bowman & Rand 1980). Part of its activity may be due to inhibition of cyclic nucleotide breakdown, part to antagonism of endogenous adenosine since theophylline is a potent inhibitor of adenosine actions in therapeutic concentrations of the drug (Fredholm 1980). Adenosine is known to potentiate mediator release from mast cells (Marquardt et al. 1978, Fredholm & Sydbom 1980) and it antagonizes the direct tracheorelaxant effect of theophylline (Fredholm et al. 1979). I have examined the possibility that lung is capable of releasing adenosine and that the release is enhanced by anaphylactic and pseudoanaphylactic reactions.     

VIP-induced cyclic AMP formation in the cat submandibular gland Potentiation by carbacholine

The intestinal secretion in cholera is evoked via the action of the cholera toxin on the intestinal mucosa. We have recently presented evidence for the involvement of the enteric nervous system in the induction of this type of secretion (Cassuto et al. 1981). We have also shown that electrical or reflex activation of the sympathetic fibres to the small intestine (Brunsson et al. 1979, Sjövall et al. 1982) increases net fluid absorption in the normal small intestine via an α-adrenergic effect. These two observations led us to investigate the possible effect of adrenergic receptor stimulation on cholera secretion.     

The Probability of Donor-Recipient Histocompatibility in Different HL-A Phenotype Combinations

The probability of donor-recipient histocompatibility within the HL—A system was investigated in 1,281 different HL—A phenotypes. The calculations were made by means of a computer program and based on haplotype frequencies. In the present study 195 haplotypes were obtained from HL—A typing of an east Swedish population, including 7 alleles of the first ("LA") locus and 9 alleles of the second ("Four") locus.
In 19 phenotypes the probability was more than 5 per 1,000 that an A match would occur, i.e. identical phenotypes in donor and recipient. Of all phenotypes investigated 30% had an incidence lower than 10 per 1,000 of a "good to acceptable" match (A, B or C match).
In an attempt to check the reliability of the results, 266 patients transplanted within the Scandiatransplant organization were classified according to the probability of different matches. Patients with a calculated A match incidence above 10 per 1,000 got A-match transplants in a significantly higher proportion than the others. Similarly, patients with an A to C match incidence below 10 per 1,000 were rarely transplanted (7% of total). It is concluded that knowledge of the incidence of histocompatibility of a patient's phenotype may be of considerable help to the clinician in his decision concerning treatment.     

Growth in a Series of Diabetic Children on Identical Treatment with "Free" Diet and Insulin 1944–1960: A Contribution to the Aetiology of Diabetic Dwarfism

An account is given of growth in a series of 195 cases of juvenile diabetes treated on a standard regimen ("free" diet + insulin) and collected during the period 1944–1960. Scrutiny of the series shows that growth was as a rule normal. Undersized children usually had small parents. A few cases of retarded growth may however be explained by excessive feeding with relative insulin deficiency. Two cases showing the classical picture of diabetes dwarfism with hepatomegaly and infantile mentality are described. Both were inadequately controlled, owing to ignorance on the part of the parents. These cases support the view that the condition is caused by relative insulin deficiency. The theory is further borne out by the improvement that took place in one of these children when she was finally brought under adequate control.     

Atrial fibrillation – new aspects on mechanism and treatment

During recent years, the exploration of different aspects of atrial fibrillation (AF) has become increasingly interesting. Thus, knowledge about basic underlying mechanisms, consequences and different modes of treatment has rapidly expanded. At a meeting in Lund, Sweden, in 1993, scientists within different fields of AF research gathered for the exchange of information. This paper is a short summary of some topics discussed at the Lund meeting and some suggestions as to how further research in this field may help to improve our understanding of this arrhythmia and the treatment of patients suffering from it.
Underlying pathoelectrophysiological mechanisms in AF have been explored in experimental models in animals and by direct recordings of different atrial myocardial electrophysiological variables both in the catheter laboratory and during open heart surgery in man. Some findings illustrate possible generalized atrial myocardial mechanisms, whilst other findings clearly indicate the possibility of localized pathoelectrophysiological mechanisms. The generally accepted hypothesis that AF is perpetuated by multiple re-entry mechanisms is, thus, both verified and modified by recent studies.
In addition to subjective symptoms and well identified thromboembolic consequences, accumulating evidence tells us that AF may precipitate a myocardial dysfunction which may be misinterpreted as an underlying factor initiating the arrhythmia.
Today's treatment of AF includes several newer antiarrhythmic drugs, different ablation techniques, the application of different electrical devices as well as different surgical methods. New, improved and simplified methods are expected.
Atrial fibrillation is the single most important supraventricular arrhythmia needing substantial further exploration of mechanisms, consequences and treatment. The Lund symposium contributed to this process by defining the state of knowledge in 1993 and outlining the need for the years to come.