The effect of acetylcholine on automaticity of Purkinje fibers was studied in isolated canine false tendon preparations with conventional microelectrode techniques. Of 15 preparations with the control spontaneous rate of 12-60 beats/min, acetylcholine in a concentration of 0.5 mug/ml decreased the spontaneous rate by 20-87% in 13 preparations. This decrease in automaticity was due to a decrease...

1. The effects of nizofenone fumarate were studied on the membrane potentials and currents of rabbit sino-atrial node preparations by means of the double-microelectrode voltage clamp method. 2. In spontaneously firing pacemaker cells, nizofenone (above 1 microM) decreased the heart rate. Above 3 microM, nizofenone reduced the maximum upstroke velocity, the amplitude of the action potential and ...

During a study of the reduction of cytochrome c by milk xanthine oxidase, it was observed that relatively impure preparations of cytochrome c were reduced more slowly than highly purified preparations. This difference was found to relate to the presence, in impure preparations, of a potent inhibitor of the reduction of cytochrome c by xanthine oxidase. This inhibitor was of interest because its...

Ž . 2q Objective: To define the electrophysiologic mechanism s by which MCI-154, a putative Ca sensitizer, produces a positive inotropic response without a positive chronotropic response, we examined effects of MCI-154 on the action potential of atrial preparations and the membrane currents of atrial myocytes. Methods: The action potentias were recorded from left atrial and sinoatrial node prep...

The yellow Iranian scorpion Odontobuthus doriae can cause fatal envenoming, but its mechanism of action is unclear. One of the reported manifestations of envenoming is moderate to severe involuntary tremor of skeletal muscle. In order to understand better the mechanism of action of this venom on skeletal muscle function, we examined the effects of the venom in vitro on chick biventer cervicis (...

Cellular electrophysiological consequences of acute ischemia superimposed on healed myocardial infarction were studied in isolated, coronary-perfused cat left ventricles 2-4 months after ligation of multiple distal tributaries of the left anterior descending and circumflex coronary arteries. Oxygenated Tyrode's solution was perfused through the left anterior descending and circumflex coronary a...

During a study of the reduction of cytochrome c by milk xanthine oxidase, it was observed that relatively impure preparations of cytochrome c were reduced more slowly than highly purified preparations. This difference was found to relate to the presence, in impure preparations, of a potent inhibitor of the reduction of cytochrome c by xanthine oxidase. This inhibitor was of interest because its...

This paper reports on the response rate and completeness of item response in a self-administered postal survey questionnaire on use of medication by retirees 60 years or older under the Brazilian Social Security System, in Belo Horizonte, Minas Gerais State, in 2003. Questionnaires were sent in two rounds to 800 postal addresses of subjects selected by simple random sampling. The response rate ...

UNLABELLED PURPOSES AND OBJECTIVES: The purposes of this study were to investigate the pharmacological skills of Finnish nurses and graduating nursing students, to determine how pharmacological skills are related to background factors and to identify differences between nurses and students and, finally, to examine how the instrument used, the Medication Calculation Skills Test, works. BACKGRO...

F3 and F4. Both of these were active in reducing the R.Q. in vitro (Table 1) but only one (F4) possessed growth-promoting activity. Since some pituitary preparations with intermedin activity (Colip, 1938; Folley, 1955) have been found to possess also an R.Q.-lowering action, Dr H. B. F. Dixon kindly tested some of our preparations for melanocyte-stimulating activity in frogs and found no relati...