Adrenergic mechanisms in the hyperglycaemia and hyperinsulinaemia of diabetic KK mice

Simultaneous occurrence of hyperglycaemia (up to 300 mg/100 ml) and hyperinsulinaemia (up to 1200 mu U/ml) was evident in the fed state in genetically diabetic KK mice, indicating insulin resistance. The hyperinsulinaemia was enhanced by alpha-adrenergic blockade and alleviated by B-blockade. Epinephrine-induced hyperglycaemia and isoproterenol-induced hyperinsulinaemia, both of which could be blocked by beta-adrenergic antagonists, were more marked in KK mice than in ICR mice. A possible significance of adrenergic mechanisms is discussed with respect to the aetiology of the metabolic disturbances characteristic of KK mice.

Effects of intraventricular injection of Sar1-Ala8-angiotensin II on plasma vasopressin level increased by angiotensin II and by water deprivation in conscious rats

The effects of intraventricular injection of Sar1-Ala8-angiotensin II (A specific antagonist of angiotensin II) on the plasma vasopressin level increased by intraventricular injection of angiotensin II and by water deprivation (46 h) were examined in conscious male rats with an indwelling cannula in the third cerebral ventricle. Blood samplings were made by decapitation and the plasma level of vasopressin was determined by radioimmunoassay. Twenty-five, 50 or 100 ng of angiotensin II produced significant (P less than 0.05) increase in plasma vasopressin level 90 sec after the injection. The effect of 50 ng of angiotensin II was inhibited significantly (P less than 0.05) at least with 100 ng of Sar1-Ala8-angiotensin II given 2 min before the injection of angiotensin II. The dehydrated rats to which 1000 ng of Sar1-Ala8-angiotensin II was given 5 min before the decapitation showed the significantly (P less than 0.05) lower median plasma vasopressin level than that of the dehydrated controls. No significant difference in plasma osmolality was noted between them. These results suggest that the plasma vasopressin response to intraventricular angiotensin II is produced via angiotensin II receptors in the brain and that Sar1-Ala8-angiotensin II inhibits the effect of endogenous angiotensin II on plasma vasopressin level under dehydration.

Effects of vagal stimulation, vagotomy and adrenalectomy on release of insulin in the rat

To evaluate the physiological role of the vagus nerve in the secretion of insulin in the rat, changes in plasma levels of insulin and sugar were examined after vagotomy with and without adrenalectomy. Male rats, fasted for 22 h, weighing about 300 g and anaesthetized with pentobarbitone sodium were used. Thirty minutes after unilateral or bilateral adrenalectomy, the first blood sample was taken just before pancreatic vagotomy and a second sample was taken 15 min after vagotomy. Pancreatic vagotomy significantly decreased levels of plasma insulin in bilaterally adrenalectomized rats. It was also confirmed that electrical stimulation of the pancreatic vagus nerve provoked an increase in levels of insulin associated with a reduction of carbohydrates in the blood. These observations support the theory that there is a vagal mechanism which modulates the secretion of insulin and suggest that the vagal mechanism is a potent factor although such a mechanism may be masked by the activity of the adrenal gland.

[A comparison between the effects of angiotensin II and angiotensin III injected into the third cerebral ventricle on vasopressin secretion in conscious rats (author's transl)]

As the greater part of the immunoreactive angiotensin II in cerebrospinal fluid has been suggested to be angiotensin III, a comparison was made between the effects on vasopressin release of angiotensin II and angiotensin III administered into the third cerebral ventricle in conscious male rats. The blood samples were collected 90 seconds after the injection of angiotensin II or angiotensin III by means of decapitation. Plasma vasopressin (microU/ml) extracted and determined by radioimmunoassay were 2.3 +/- 0.8, 6.7 +/- 5.0, 14.0 +/- 2.2, 16.3 +/- 4.3 and 20.7 +/- 2.5 (mean +/- SEM), respectively following the injection of 0, 10, 25, 50 and 100ng of angiotensin II. The increases in plasma vasopressin produced by angiotensin II 25, 50 and 100ng were statistically significant (p less than 0.05). On the other hand, plasma vasopressin following the injection of 22.7 and 45.4ng of angiotensin III, which are equimolar to 25 and 50ng of angiotensin II each, were 14.9 +/- 2.7 and 16.3 +/- 5.6, respectively. No significant difference was found between the effect on plasma vasopressin of angiotensin II and that of angiotensin III at the dose level of 24.3 or 48.6 p. mol. These data indicate that angiotensin III is equipotent to angiotensin II in terms of vasopressin release when administered into the third cerebral ventricle. The possible role of angiotensin III in the brain on vasopressin secretion is discussed.

[Establishment of a colony of Japanese white rabbits free from coccidia and their breeding performance (author's transl)]

A colony of rabbits free from coccidia was established in 1974 by weaning young at 25 days of age from dams infected with coccidia. Until now Bordetella, Pasteurella and Psoroptes cuniculi have not been detected either, and neither diarrhea nor death has occurred in weanlings of the colony. However, the mortality of sucklings was significantly high owing to cannibalism and tread by their dams. The weaning rate was effectively improved by use of a large nursing cage (3,100 cm2) and sterilized hay on a stainless steel mesh floor of the nursing cage.

Uptake of uranium by various cell fractions of Chlorella regularis

To know what kinds of the cell components of Chlorella regularis are concerned with uranium binding, uptake of uranium by various cell fractions was examined. The uptake value (microgramU/mg starting dry cells) of the hot water-treated cells was almost the same as that of the starting dry Chlorella cells, showing that the cell components extracted with hot water were not so concerned with uranium binding. The cell components extracted with dilute alkali seemed to play an important role in uranium binding, and those extracted with chloroform-methanol seemed to be partly concerned with uranium binding. The cellulose fraction of the cells was scarcely concerned with uranium binding. In the dry cells, 34% of uranium taken up existed in the cell walls. However, in the living cells, 85% existed in the cell walls. The above results showed that the dry or the hot water-treated cells are the most convenient for uranium recovery from the aqueous systems.

Changes in efferent activities of the gastric vagus nerve by administration of glucose in the portal vein

Injection of glucose in the portal vein, as well as in the left carotid artery, brought a transient decrease in efferent discharges of the gastric vagus nerve, whereas venous injection of regular insulin brought a gradual increase in the discharges.

Production of elastic electrodes for nerve stimulation

For better evoking and monitoring electrical activities of visceral nerves, a elastic electrode made of conductive plastic and silicone gum is developed.

[A micro-method developed for prothrombin time assay (author's transl)]

Prothrombin time was measured by a newly developed micro-method using a plastic film available in the market (PARAFILM, American Can. Co.). The comparative study of this micro-method with that of Quick in rats disclosed a good correlation, with correlation coefficient of 0.951, supporting the usefulness of the method for examination of blood coagulability. The new method gave the physiological values of 9.8 sec in rabbits, 12.5 sec in dogs, 13.3 sec in mice, 14.8 sec in cats and 16.0 sec in rats, respectively. Among them, guinea pigs took the longest time of 25.3 sec for the coagulation.

Mode of action of 6-cyclohexyl-1-hydroxy-4-methyl-2(1H)-pyridone ethanolamine salt (Hoe 296)

Mode of action studies were made with Hoe 296, a new synthetic antimycotic, mainly in Candida albicans. The specific parameters examined included possible effects on (i) osmotic fragility, (ii) respiration, (iii) uptake and incorporation of radioactive leucine and adenine, and (iv) leakage or efflux of intracellular K+ and other materials. As a result, fungitoxic activity of Hoe 296 appears to be attributed to inhibition of uptake of precursors of macromolecular syntheses from the medium. Uptake and accumulation of leucine in the internal pool of starved cells was more susceptible to the drug than subsequent incorporation into proteins. Hoe 296 was also effective in altering the cell permeability, but greater drug concentrations were required to induce appreciable leakage of cellular constituents, such as 260 nm-absorbing materials, folin-positive substances and potassium ions, from the cells. Osmotic fragility or endogenous respiration was virtually insensitive to the drug. Partial inhibition by relatively high concentrations of Hoe 296 of the respiratory activity of yeast cells or mitochondria therefrom with exogenous substrates can be explained by decreased uptake of the substrates from the medium.

Effects of epinephrine and theophylline on lipolytic response in hereditary diabetic mice

In non-obese but diabetic 15-week-old KK mice which showed fatty liver histopathologically, the content of liver lipids and the levels of blood glucose and plasma IRI were greater than those in the control ICR mice of the same age and were quite similar to those in GTG-obese mice. In 6-week-old KK mice which excreted no glycosuria and showed normal hepatic tissues, only plasma IRI level was slightly elevated as compared with that in the control mice. The cyclic 3',5'-AMP stimulators like epinephrine and theophylline exerted far less potent stimulatory effects on lipolytic activity in 6-week-old KK mice than in the control mice, as in diabetic 15-week-old KK mice and GTG-obese mice. Theophylline potentiated the lipolytic effect of epinephrine lineraly in KK mice, the tendency being different from that in the control mice, and only the submaximal rate was obtained. Furthermore, the inhibitory effect of theophylline on PDE from the epididymal adipose tissue was less potent in 6-week-old KK mice than in healthy ICR mice of the same age.

Capillary tube urinalysis for small animals

A simple method was devised using a capillary tube to collect urine for urinalysis. This method offers the following advantages: the animal is not adversely influenced; the collection and analysis of the urine is repeatable; the amount of urine required is small; because of the simplicity of the method, the number of samples tested in a given time can be increased; and contamination with foreign material is reduced, permitting more accurate evaluation of the urinary sediments.

[Effects of 9-fluoro-11 beta, 21-dihydroxy-16 ampha-methylpregna-1, 4-diene-3, 20-dione (A41 304) and dexamethasone on the fetus of mice and rats]

A41 304 at 400 mug/kg produced depression of body weight gains in the rat dams but did not increase the number of the fetuses with gross malformations. At 400 mug/kg of dexamethasone, body weight gains of the rat dams were markedly depressed and fetuses presented cleft palate and depression of the placental weight, body weight and crown-rump length. As for the influence of both drugs upon the fetal skeleton, ossification of the odontoid process and metatarsus was delayed and lumbar ribs increased. Dexamethasone at 400 mug/kg, in addition to these findings, caused prominently delayed ossification to the caudal vertebrae. When A41 304 at 1600 mug/kg and dexamethasone at 400 mug/kg were given to pregnant mice, cleft palate occurred with high incidences, but neither visceral abnormalities nor skeletal malformations attributable to the drug administration were observed. The critical period of cleft palate which was noted in the mice given A41 304 was day 11 through day 15 of pregnancy, mainly 11 approximately 13 of pregnancy. Cleft palate was seen in a dose-related manner in either A41 304-treated groups or dexamethasone-treated groups, but the incidence at the same dosage level was higher in dexamethasome-treated groups than in A41 304-treated groups.