Young W. Cho

Comparative toxicity of chloroguanide and nitroguanil

Abstract The pharmacologic actions of these two antimalarial drugs were compared in mice, rats, cats, and dogs. The cardiac effects of both chloroguanide and nitroguanil include depression of excitability of rat atrial muscle, depression of respiratory enzymes of mouse heart homogenate, and depression of myocardial contractility of cat heart. The dog showed an elevation in cardiac output following nitroguanil, but no change following chloroguanide. The decrease in fertility and reduction of body weight induced by chronic administration of nitroguanil in the mouse were less severe than those of chloroguanide. In the cat, chloroguanide but not nitroguanil, reduced gastric secretion. Both drugs suppressed the parasitemia and prolonged the survival of the rat and mouse infected with Plasmodium berghei .

Myocardial Metabolic Changes During Acute Hemorrhage

It was previously observed that the physicochemical properties of cardiac actomysin and myosin are altered during acute hemorrhage, acute endotoxic shock, shocklike syndrome following total cardiopulmonary bypass, and acute hypoxia.’Changes in the myocardial contractile proteins may be due to acute tissue anoxia, certain electrolytic changes, and other unknown mechanismS.2 In addition, it has been suggested that histamine, serotonin (5-hydroxytryptamine), catecholamines, or other biogen amines released during various forms of cardiovascular shock might act as chemical mediators to induce profound changes in cardiovascular reactivity.3-5 Since cardiac mitochondria (sarcosomes) may be important cellular particles, producing and transferring energy (adenosine triphosphate (ATP) and others) to be utilized by myocardial contractile proteins in performing mechanical work, we have investigated mitochondrial functional changes occurring in acute hemorrhagic shock.

Pathologic physiology and chemotherapy of Plasmodium berghei. VIII. Liver enzymes and the influence of hexachloroparaxylene (WR 17,206).

Abstract Hexachloroparaxylene prolonged the survival of the mouse and rat infected with Plasmodium berghei . The cardiac effects of this compound consisted of: (a) Depression of respiratory enzymes of the heart homogenate of the mouse; and (b) prolongation of effective refractory period and increase in excitability of the isolated rat atrial muscle. The respiratory enzymes of liver homogenate were also depressed by the administration of hexachloroparaxylene to the control and infected mice. The development of malarial infection caused a depression in activity of liver enzymes associated with an elevation in lactic acid level in the blood.

Differences in the Effects of Inhalation of Sulfur Dioxide and Cigarette Smoke

In the anesthetized dog the inhalation of sulfur dioxide caused bronchoconstriction which persisted even after acute and chronic denervation, The basic mchanisms responsible for this bronchoconstriction as well as the accompanying bronchial arterial vasodilatation are different from those activated during the inhalation of cigarette smoke.

Pathologic physiology and chemotherapy of Plasmodium berghei: IV. Influence of chloroquine on oxygen uptake of red blood cells infected with sensitive or resistant strains☆

Abstract The oxygen uptake of erythrocytes was measured in vitro in a chamber with an oxygen electrode. Non-malarial blood showed an increase in oxygen uptake following the addition of chloroquine at 10 −8 , 10 −7 , or 10 −5 M . Blood from mice infected with Plasmodium berghei which can be controlled by in vivo administration of chloroquine responded to in vitro addition of chloroquine, by a fall in oxygen uptake. Blood from mice infected with Plasmodium berghei known to be resistant to chloroquine behaved differently. The in vitro addition of chloroquine did not depress oxygen uptake of the erythrocytes but caused an increase.

Effects of Perhexiline on myocardial phosphorylase activity, myocardial catecholamine content and heart rate.

A study was conducted on the effects of perhexiline on myocardial phosphorylase activity, myocardial catecholamine content and heart rate. Phosphorylase a activity and heart rate were investigated as an indicator of sympathetic nerve tone in order to clarify the characteristic of perhexiline with regard to the effects on myocardial metabolism in hyperthyroid rats and catecholamine deficient rats. Myocardial catecholamine and phosphorylase a activity were measured by von Eulers method and Coris method respectively. Conclusion of this study are summarized as follows: 1) Perhexiline reduces the heart rate, and its effect is not always dependent upon the changes in myocardial norepinephrine content. 2) Perhexiline reduces myocardial phosphorylase a activity. It cannot be always said that the reduction is dependent upon the changes in myocardial norepinephrine. 3) Though slightly different from propranolol and dichloroisoproterenol, perhexiline possesses cardiac effects resembling beta-blockers.