Reiji Imaizumi

Effect of win 18501-2 on the content of catecholamines and the number of catecholamine-containing granules in the rabbit hypothalamus

Der Hypothalamus von Kaninchen wurde nach Win 18501-2-Injektion biochemisch und elektronenmikroskopisch untersucht. Die Behandlung erzeugte auffallende Veränderungen im Noradrenalingehalt und in der Anzahl der Katecholamine enthaltenden granulierenden Vesiculae im Hypothalamus. Die Resultate scheinen zu zeigen, dass diese charakteristischen Vesiculae nur Noradrenalin enthalten und dass die Sedation des Kaninchens nach der Injektion von Win 18501-2 auf der Verminderung des Noradrenalins und der charakteristischen Vesiculae beruht.

Selective release of noradrenaline and adrenaline from isolated adrenal medullary granules

Abstract The release of catecholamine from adrenal medullary granules isolated practically free from mitochondria by membrane filters was investigated. The release of noradrenaline was greater than that of adrenaline in the presence of calcium, ATP-magnetium and reserpine (0.01mM). However, in the presence of tyramine, adrenaline release was greater than noradrenaline release.

Stimulatory effect of reserpine on monoamine oxidase in guinea pig heart

Abstract (1) In slices, homogenates or mitochondrial fractions of the hearts of guinea pigs after reserpine treatment, the amounts of deaminated metabolites of 14 C-norepinephrine were more than in the controls. This seems to be because heart mitochondrial monoamine oxidase (MAO) is activated by reserpine. So far activation of MAO by reserpine could only be demonstrated in vivo , or in slices in vitro. (2) When 14 C-dopamine or 14 C-tyramine, better substrates for mitochondrial MAO than norepinephrine, were used as substrates for MAO activity, there was little increase in their deamination after reserpine-treatment. (3) Even when 14 C-norepinephrine was used as a substrate for MAO, there was little or no increase in its deamination after reserpine treatment when measured in hypotonie medium. The increase seen with normal heart preparations was probably caused by swelling or structural changes of heart mitochondria leading to increased deamination of 14 C-norepinephrine. (4) These findings suggest the interesting possibility that reserpine may act on the mitochondrial membrane or structure to increase the penetration of norepinephrine to mitochondrial MAO. In this way the deamination of norepinephrine would be increased in hearts after reserpine treatment.

Effect of reserpine on monoamine oxidase activity in guinea pig heart

Abstract Reserpine treatment activates mitochondrial MAO activity of guinea pig hearts. Reserpine may act on the mitochondrial membrane or structure to increase the penetration of norepinephrine to mitochondrial MAO. In this way the deamination of norepinephrine would be increased in reserpinized hearts.

Structural changes in the catecholamine containing granules of adrenal medulla.

Abstract Turbidity changes in the catecholamine containing granules of adrenal medulla were caused by Ca 2+ , ATP-Mg 2+ , reserpine or tyramine which are known to stimulate the release of catecholamine from the granules. However, the turbidity change caused by tyramine was slight. It was suggested therefore, that Ca 2+ , ATP-Mg 2+ or reserpine might cause some structural changes in the catecholamine containing granules, resulting in a release of catecholamine from the granules. It is uncertain whether the slight changes in the structural state of the granules caused by tyramine contribute to the release of catecholamine from the granules stimulated by tyramine.

MECHANISM OF THE ANTIHYPERTENSIVE EFFECT OF ALPHA-METHYLDOPA.

IT has recently been reported that a decarboxylase inhibitor, α-methyl-3,4-dihydroxyphenylalanine (α-methyldopa), lowers the tissue norepinephrine level of various species of animals1,2. Moreover, this decarboxylase inhibitor has been demonstrated to be antihypertensive in man3.