The effects of some ions and drugs on the aconitine-induced fibrillation and flutter of the isolated mammalian Purkinje fibers were studied from the alteration of transmembrane potentials with intracellular microelectrodes. The concentration of potassium, sodium or calcium ions contained in the perfusing Tyrode solution was varied in the stage of the fibrillation and flutter, and EDTA, tetrodotoxin and propranolol (β-blocker) were added the perfusate and theirs effects were observed. From the results, the ionic background of the fibrillation was estimated and the differences in nature between the fibrillation induced by aconitine and by other methods were discussed.

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Eight mongrel dogs were operated to produce pulmonary stenosis. Eight weeks after the operation, the free wall of the right ventricle with myocardial lesions was excised and a strip of the muscle was prepared for this study. The preparations immersed in oxygenated Tyrode's solution were given several drugs, such as Thiamine pyrophosphate (Cocarboxylase), Thiamine Tetrahydrofurfuryl Disulfide (TTFD), Thiamine Propyl Disulfide (TPD), Thimamine hydrochloride. Adenosine Triphosphate (ATP) and Desacetyl-lanatoside C (Lanatoside C). The effect of these drugs on specimens were observed electrophysiologically regarding transmembrane action potential, its duration and contractile tension as compared with the normal heart muscle.

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The turnover rate of actomyosin of myocardium and skeletal muscle was studied in control dogs and in those with experimentally produced aortic insufficiency. Based on the concept that vitamin B₁₂ is an activating drug for myocardial metabolism, a large dose of it was given some of the dogs with aortic insufficiency to study the effect of vitamin B₁₂ on the turnover of actomyosin in the overloaded heart. During the early period, when there was an acute increase in the load on the heart, the turnover rate of myocardial actomyosin in the dogs with aortic insufficiency increased and that of dogs administrated vitamin B₁₂ increased remark-ably. However, during a relatively stable period (from 9th-30th day after production of aortic insufficiency), the turnover rate of myocardial actomyosin in both dogs with aortic insufficiency and those administrated vitamin B₁2, approached control levels. From these observations it seems that increase in turnover rate is an important compensatory factor in the diastolic-overloaded heart and administration of vitamin B₁2 is useful in treatment of the overloaded heart.

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A new perfusion method for the dog kidney was introduced. In this method the left kidney of the recipient dog was perfused with the donor's blood using a pump-oxygenator system, while the renal nerve of the perfusion side was intact. Blood vessels of the perfused kidney showed good response to various vaso-active substances and to renal neave stimulation.

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The mechanism of the anoxic spells in the patient with tetralogy of Fallot is still uncertain, but beta adrenergic stimulation has been shown to accentuate cyanosis and occasionally to precipitate an anoxic spell. The purpose of the present study is to investigate the hemodynamic responses to isoproterenol (adrenergic beta stimulant) and propranolol (adrenergic beta blockade). Materials and Methods: Eleven children ranging in age from 3 to 14 years have been studied at cardiac catheterization (tetralogy of Fallot 7 cases, pulmonary stenosis with intact ventricular septum 2 cases, ventricular septal defect 1 case, patent ductus arteriosus 1 cases). All patients were sedated with hydroxyzine hydrochloride, secobarbital and pethidine HCl. The pressure pulses of pulmonary artery, right ventricle and femoral artery were obtained by the Siemens electro manometer. Determinations of oxygen satura-tions were obtained with the gas analyser (In-strumentation Laboratory) on arterial, pulmo- nary and mixed venous blood. Oxygen consumptions were measured by Fukuda Irika's respirometer. The phonocardiogram and the first derivative of right ventricular pressure pulse (dp/dt) were simultaneously recorded. Isoproterenol (0.1mg/20cc in 5% dextrose in water)was infused intravenously until the heart rate increased by 50 per cent. Then blood samples were obtained and pressure pulses were recorded. Thereafter, while the action of isoproterenol persisted, the infusion of propranolol in a dose of 5γ/kg (2mg/20cc in 5% dextrose in water) was administered, and the parameters were restudied. The angiocardiogram was obtained in one case before and after isoproterenol infusion. Results and Discussion: In tetralogy of Fallot the isoproterenol in-fusion resulted in an increase of right ventricular systolic pressure and a decrease of pulmonary systolic pressure. Pulmonary blood flow was decreased and systemic blood flow and right to left shunt were increased, so arterial oxygen saturation was markedly decreased. In angio-cardiogram the marked narrowing of the right ventricular outflow tract was demonstrated after isoproterenol infusion. In simultaneously recorded phonocardiogram the ejective systolic murmur due to pulmonary stenosis was decreased by isoproterenol infusion. In pulmonary stenosis with intact ventricular septum the pressure gradient of pulmonary artery and right ventricle was markedly increased, but arterial oxygen saturation was unchanged after isoproterenol infusion. Thereafter, while the action of isoproterenol persisted, a infusion of propranolol was administered. In tetralogy of Fallot the propranolol infusion resulted in an increase of arterial oxygen saturation. And the systolic pressure gradient of pulmonary artery and right ventricle was decreased. Pulmonary blood flow was increased and systemic blood flow and right to left shunt were decreased. So the patients were recovered from anoxic state. The mechanism of the anoxic spells in tetralogy of Fallot is still uncertain, but our study suggests that the increase of the contraction in the outflow tract of right ventricle makes the hypoxic condition. Relaxation of the outflow tract of right ventricle is seen after propranolol, and the patient is recovered from anoxic condition. In one case with tetralogy of Fallot in age of 9 months who had frequent cyanotic at-tacks we used propranolol orally 5 mg a day. After propranolol there has been no anoxic spell in this patient. So it may have been some practical usefulness in prevention and treatment of anoxic spells in tetralogy of Fallot.

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