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Introduction. The "warm-up" effect in angina may represent ischaemic preconditioning, which is mediated by adenosine A1-receptors in most models. Protection may also occur against ischaemic left ventricular (LV) dysfunction. We investigated whether warm-up can be reproduced by a selective adenosine A1-agonist, GR79236 (Glaxo-Wellcome). Methods. 25 patients with three vessel coronary disease and normal resting LV function entered a double-blind crossover study, receiving IV GR79236 10μg/kg or placebo on mornings one week apart. Two symptom-limited supine bicycle exercise (ex) tests were performed 30 minutes apart on each day. Equilibrium radionuclide angiography (ERNA) was used to derive regional ejection fractions (REFs) for 9 LV sectors. Sectors were defined as ischaemic or nonischaemic based on whether REF fell or not during the first test following placebo. Results. During the second of two ex tests following either placebo or drug, the onset of chest pain or 1mm ST depression was delayed and occurred at a higher rate-pressure product, whilst the mean REF of ischaemic sectors increased (P

Co-cultivation studies in different combinations have been carried out between cells which have been found to be positive for the fragile (X) (q27) and control cells. As no increase or decrease was discernible in the level of Fra(X) detected in 'positive' cells, and no fragility was introduced into the 'negative' cells, it was concluded that there had been no intercellular co-operation, and a diffusible expression or suppression factor was not involved.