Anisatin, a potent GABA antagonist, isolated from Illicium anisatum

The neuropharmacological properties of anisatin were tested on the frog spinal cord and the crude synaptic membrane from rat brain. Anisatin (10(-5) M) reduced the amplitude of dorsal root potentials induced by stimulation of the adjacent dorsal root and presynaptic inhibition of the ventral root reflex. Anisatin shifted the dose-response curve for GABA-induced depolarization in the primary afferent terminal to the right and also reduced the maximum response to GABA. [3H]Muscimol binding to the crude synaptic membrane was not inhibited by anisatin. These results indicate that anisatin is a picrotoxin-like, non-competitive GABA-antagonist.

A simple method to determine the ratio of cardiac to vascular beta-receptor blockade in the rat in vivo

We have devised a simple method to determine the ratios of cardiac to vascular beta-receptor blockage (C:V ratios) in normotensive rats anesthetized with pentobarbital, and applied it to six beta-adrenergic blocking drugs (beta-blockers). Mean blood pressure (BP) and heart rate (HR) were recorded. Isoproterenol (3 ng-100 microgram/kg, i.v.) was cumulatively injected before and after the intravenous administration of beta-blockers at two dose-levels. Thus shifts of the dose-response curves in BP and HR were observed. "In vivo pA2" values were calculated in molar doses per kg by Schild plots. The C:V ratio was calculated as antilogarithm of the difference of the mean in vivo pA2 value in HR from that in BP. Those of atenolol, bometolol, bunitrolol, pindolol, propranolol, and sotalol were 9.77, 8.13, 2.95, 1.38, 1.20, and 0.71, respectively.

Acute and subchronic effects of bometolol on blood pressure in hypertensive rats

Bometolol is a cardiospecific beta-adrenergic blocking drug. The effect on blood pressure was determined in hypertensive rats in acute and subchronic experiments. In acute experiment bometolol, 10-30 mg/kg, p.o., was given to spontaneously hypertensive rats; deoxycorticosterone and salt hypertensive rats; and two kidney, one clip hypertensive rats. Blood pressure was determined continuously for 8 h and after 24 h in unanesthetized condition. The blood pressure lowered by bometolol was dose-dependent in three types of hypertension. In subchronic experiment, bometolol at a dose of 10-30 mg/kg or 100-300 mg/kg, p.o., were given for 5 weeks to deoxycorticosterone and salt hypertensive rats; and two kidney, one clip hypertensive rats. Bometolol did not show antihypertensive effect in either type of hypertension, although bometolol decreased heart rate dose-dependently. Bometolol treatment at the above doses decreased plasma renin activity, heart and kidney weights, and incidence of vascular lesion in either hypertensive rat. Toxic symptom was seen 3 days after bometolol treatment of 300 mg/kg in deoxycorticosterone and salt hypertensive rats.

Clinical features and biochemical aspects of red blood cells in Hb Hirosaki

Hb Hirosaki is a new unstable variant in which CE 1 phenylalanine of alpha-chain is substituted by leucine. Seven patients with hemolytic anemia were found in one family and Hb Hirosaki was detected in four of them. In clinical feature some differences of severity were observed between child and adult patients. The child cases showed relatively severe symptoms with repeated hemolytic crises and drug sensitivity. Otherwise most of adult cases had only mild hemolytic process throughout their past life. The variety of clinical severity suggests that the expression of abnormal gene may be various in this disorder. The mode of inheritance seemed to be autosomal dominant and all the cases in this report were heterozygous state. Macrocytic and hypochromic anemia was characteristic in most cases and red blood cells containing Heinz bodies were dominant in peripheral blood from the splenectomized patients. Accelerated glycolysis and enhanced ATPase activity were outstanding features in the metabolism of erythrocyte in this disorder. The instability of reduced glutathione was also found in three of five cases.

Determining the absorption coefficient of absorbing thin films with optical waveguides

A new simple method of determining the absorption coefficient of absorbing thin films is proposed as an application of the complex propagation constant of a guided wave in a thin film optical waveguide. This method was applied to both cases as examples: low index (polyurethane film top layer containing rhodamine 6G dye) and high index (evaporated ZnSe film top layer) absorbing top layers on the main glass guide. The absorption coefficients so determined were compared with the values given by Lambert's method.

The potent depolarizing action of palytoxin isolated from Palythoa tubercurosa on the isolated spinal cord of the frog

1. The effects of palytoxin (PTX) isolated from Palythoa tubercurosa were tested on the isolated intra-arterially perfused spinal cord of the frog. The resting and evoked potentials were recorded by means of a sucrose-gap technique. 2. PTX caused a marked depolarization of both ventral and dorsal roots. The minimum effective concentration was extremely low, approximately 10(-11) M. During the depolarization the evoked ventral and dorsal root potentials were markedly reduced in amplitude. The ventral root reflex was first augmented and then decreased. 3. The depolarization caused by PTX was markedly reduced when the preparation was perfused with NaCl-deficient medium. However, tetrodotoxin (10(-7) M) only slightly inhibited the depolarization. 4. In a high Ca2+ medium (3.6 mM), the time required to reach the maximum depolarization evoked by PTX was significantly prolonged. In contrast, in a low Ca2+ medium (0.9 mM), PTX caused a marked depolarization soon after application. In a Ca2+-free, Mg2+ (9.0 mM) medium, PTX caused rhythmic oscillatory potentials in both ventral and dorsal roots. 5. The potency of N-acetyl PTX was one hundredth that of the parent compound. 6. It is suggested that PTX may interfere with the stabilizing action of Ca2+ on the neuronal membrane, consequently facilitating Na+ permeability. The primary amine in the PTX molecule may be important for its pharmacological action.

[Effects of benzodiazepine derivatives on gamma-motor system in rats (author's transl)]

Effects of four benzodiazepine derivatives on gamma-activity were examined in the anesthetized rat. Diazepam and 5-(o-chlorophenyl)-1-methyl-7-nitro-1, 3-dihydro-2H-1, 4-benzodiazepin-2-one(ID-690) in a dose of 2.5 mg/kg (i.p.) showed depressant effects on gamma-activity. The depressant effects of 5.0 mg/kg (i.p.) lasted for more than 60 min. Nitrazepam had a slightly weaker effect than the above two drugs and the effect was evident after an administration of 5.0 mg/kg; the effect of 10 mg/kg(i.p.) lasted for more than 90 min. The effect of clonazepam was much weaker than effects of the other three drugs. A dose of 20 mg/kg(i.p.) was required to produce an obvious depressant action, and the effect appeared after a longer latency of about 20 min. ID 690 (5.0 mg/kg, i.p.) depressed the augmented response of the gamma-activity in response to pinna stimulation. The effect of diazepam on the augmented responses was observed with the same dose. In contrast, much higher doses of nitrazepam and clonazepam were required to induce an obvious depressant effect on the augmented gamma-activity. It is suggested that the difference in potency in depressing gamma-activity of these derivatives is one of the factors characterizing their pharmacological properties.

Clinical evaluation of 5-hydroxy-L-tryptophan as an antidepressant drug

Effectiveness of 5-hydroxy-L-trytophan as an antidepressant drug was studied with 59 patients with depressive symptoms using Rating Scale for Depression made by Clinico-Psychopharmacology Research Group in Japan for a preparatory step of a double blind clinical study of 5-hydroxy-L-tryptophan treatment of depression. A daily dose of 150--300 mg of 5-hydroxyl-L-tryptophan was administered for three weeks. Favorable responses were observed in 40 patients (67.8%), of whom 13 patients were markedly improved. These effects were noticed in 32 patients (80% of the improved patients) within a week of the treatment. Analysis of General Improvement Rating in the various subtypes of depressive symptoms indicated that endogenous depression and involutional or senile depression were the preferable indication of 5-hydroxy-L-tryptophan loading. The main side effects of 5-hydroxy-L-tryptophan were gastrointestinal disturbances which were minimized by the simultaneous administration of metoclopromide or trihexyphenidyl.

Alterations in spontaneous activity of the isolated frog spinal cord in Calcium-free environment

Spontaneous electrical activity of the isolated frog spinal cord was examined in Ca2+-free environment. Spontaneous discharges from the ventral root altered in four distinguishable steps. The first step was an immediate increase in the rate of spontaneous discharges and the second was a gradual decrease. The third was the occurrence of rhythmical bursts, and the last, the appearance of continuous firing. The rhythmical bursts could be depressed by the addition of metabolic inhibitors (ouabain or dinitrophenol in a concentration of 5 x 10(-5) M) as well as of Ca2+-chelating agents (EDTA or EGTA in a concentration of 10(-3) M). Our results suggest that the occurrence of the rhythmical bursts requires a metabolic pumping process to redistribute Na+ and K+ across the membrane and a small amount of Ca2+ for transmitter secretion.

Effects of beta-(p-chlorophenyl)-GABA (baclofen) on spinal synaptic activity

In the isolated perfused spinal cord of the bullfrog, baclofen caused a reduction in the rate of spontaneous discharges in the ventral root at lower concentrations than GABA. The inhibitory effect of baclofen was fully present in a chloride-free medium, whereas that of GABA was markedly reduced. In contrast to GABA, which depolarized the dorsal root, baclofen produced a hyperpolarization in the dorsal root. Moreover, baclofen produced a hyperpolarization in the ventral roots. In the rat, the development of spinal reflex inhibition by baclofen was slow and the effect was long-lasting. Baclofen decreased dorsal root reflexes, suggesting a decreased excitability of presynaptic fibres. Baclofen produced a more pronounced and faster inhibitory effect on monosynaptic reflexes than on polysynaptic reflexes. In the monoamine depleted rat, the effect of baclofen on both types of reflexes was markedly reduced. It appears that catecholamines are involved in the effects produced by baclofen.

[Effects of divalent cations on the muscle spindle of frogs]

Afferent discharges were recorded in the nerve from the isolated muscle spindle of the m. extensor longus digiti IV of the bullfrog. Discharges of about 10 Hz generated by a sustained stretch were reduced concentration-dependently when Ca2+, Mg2+ or Mn2+ (1.0 approximately 8.0 mM) was added to normal Ringer's solution containing 2.0 mM Ca2+. In terms of the decrease of discharges following the addition of Ca2+ or Mn2+ (4.0 mM), abortive spikes were observed. With an excess of Mg2+ (4.0 mM), abortive spikes were not apparent. Removal of Ca2+ from the Ringer's solution caused an increase in the rate of discharges, and normal levels were restored by the addition of Ca2+ (2.0 mM), Mg2+ (2.3 mM) or Mn2+ (1.8 mM). Application of much higher concentrations of these ions to the nerve trunk produced no alterations in the conduction of afferent discharges. It appears that Ca2+ in the external medium contributes to the inhibition of the mechanism responsible for generating afferent discharges in the muscle spindle and that Ca2+ action is not specific since Mg2+ and Mn2+ can act as substitutes for Ca2+ to regulate afferent discharges.

[Effect of drugs affecting sodium permeability on the muscle spindle of frogs]

Afferent discharges of about 10 Hz were recorded in the nerve from the isolated muscle spindle of the m. extensor longus digiti IV of the bullfrog subjected to a sustained stretch. When grayanotoxin-I, ventridine or aconitine was added to the Ringer's solution, the rate of discharges markedly increased and thereafter decreased. In these terms of decrease of discharges, abortive spikes were observed. The rate of discharges was markedly decreased by the application of procaine, diphenylhydantoin, chlorpromazine or tetrodotoxin. With the latter three drugs, abortive spikes were observed in the course of decrease of discharges. Increase of the discharge rate induced by grayanotoxin-I, veratridine and aconitine was antagonized by procain. No alteration was evident in the conduction of afferent discharges, when test drugs were applied to the nerve trunk in concentrations sufficient to change the rate of discharges when applied to the muscle spindle. These results suggest that the rate of the muscle spindle discharges is closely related to sodium permeability of the membrane.

The chloride-dependent depression by GABA in the frog spinal cord

Spontaneous activities from ventral and dorsal roots of the isolated perfused spinal cord of the bullfrog were inhibited by GABA. beta-Alanine showed a strong and glycine a weaker inhibitory effect. The inhibitory effect of GABA was markedly reduced in a chloride-free medium, whereas glycine and beta-alanine still showed an inhibitory effect similar to that seen in normal medium. Employing the sucrose-gap method, a marked depolarization in the dorsal root and a small but obvious hyperpolarization in the ventral root were found by the application of GABA. These results support the view that GABA is one of the transmitters involved in pre- and postsynaptic inhibition of the spinal cord. The postsynaptic hyperpolarizing effect of GABA on motoneurones would be caused directly through increased permeability of the membrane to chloride ion. The depolarizing effect of GABA on primary afferent terminals is discussed in connection with chloride dependency.

Urinary excretion of steroids by Japanese women with breast cancer

The urinary excretion of steroids was determined in premenopausal patients with advanced breast cancer in the non-menstrual phase and in control women in the follicular phase, ovulatory stage, and luteal phase. The estrone level in the urine of cancer patients was higher than that in the urine of control women at any phase. Excretion of 17 beta-estradiol in the follicular and luteal phases was similar in the urine of control women and cancer patients, but estradiol and estriol levels in the ovulatory stage of control women were higher than those of cancer patients. The estriol level in the urine of control women in the luteal phase was also higher than that of cancer patients. Total 17-ketosteroid was lower in the urine of cancer patients than in that of controls at any phase. Among the fractions of 17-ketosteroids, only dehydroepiandrosterone was excreted at a higher level by cancer patients than by control subjects.