EFFECT OF TETRODOTOXIN, EPINEPHRINE AND NOR-EPINEPHRINE ON GLUCOSE UPTAKE OF THE RAT DIAPHRAGM

EFFECT

OF

TETRODOTOXIN,

NOR-EPINEPHRINE OF THE KANAME

EPINEPHRINE

ON GLUCOSE RAT

AND

UPTAKE

DIAPHRAGM

KURIAKI

AND IUKO

WADA

Department of Pharmacology, NipponMedical School, Tokyo Received

In a previous fish, tetrodotoxin,

for

publication

paper (1), we have reported on dehydrogenase,

and choline acetylase, in an attempt

November

8,

1958

our studies on effect of the poison of globe

yellow enzyme, cytochrome-c-oxidase, to clarify the mechanism

cholinesterase

of toxic action of the poison.

This time, we have investigated effect of the poison on the glucose uptake and glycogenesis of the isolated diaphragm also performed

of the rat.

Comparison

of epinephrine

and nor-epinephrine

was

as for their action on this process .

MATERIALSAND METHODS Glucose uptake was evaluated by the difference in glucose concentration of the medium, before and after incubation at 37°C with the diaphragm for 30 minutes, following Liebecq's description (2). The medium was Krebs and Henseleit's buffer solution, in which sodium bicarbonate was added to a concentration of 6 mg% and glucose to 140 mg%. In each vessel comes the hemi-diaphragm (100-200 mg), which was taken from the young rat of the body weight of 70 to 110 g fasted a day before the experiment. For determination of glycogenesis, larger rat of the body weight of around 130 g was used, and the description of O. Walaas and E. Walaas (3) was followed. The diaphragm (300-500 mg) was placed in each vessel with 1.0 ml of Krebs-Henseleit's solution and 0.1 ml of the solution of a substance, and incubated for 30 minutes at 37°C. The diaphragm was then submitted to glycogen analysis, the content of which was expressed with the amount of reducing sugar obtained by its hydrolysis. Analysis of the sugar was performed with the colorimetric method of Nelson-Somogyi. Globefish poison concentrate (LD;,,=17 ,mg/g),epinephrine and nor-epinephrine were added to the mixture in the vessel. They are preparations of the Sankyo Co., and generously supplied by Mr. H. Mizuta of the company. RESULTS AND DISCUSSION The from

results

of the experiment

the concentration

Furthermore,

this action

at a concentration

are summarized

of 5 x 10-' on increases appears

glucose

to be potentiated

of 1 x 10-5 which

in the Tables

is ineffective

uptake by the

in the

1 and 2.

of the diaphram presence

absence

of insulin, of insulin

Tetrodotoxin significantly. since even tetrodotoxin

increases mg/g/hr

with statistically in the control

tetrodotoxin. the control.

obviously

with insulin

significant

alone to 12.8 mg/g/hr

The poison at 1 x 10' doubled Compared

1 x 10' of tetrodotoxin,

from 10.4

in the presence of insulin and

the glycogen production

with other enzyme systems, glucose uptake

little less sensitively than cytochrome-c-oxidase bited by I x 10

difference the glucose uptake

and cholinesterase

in comparison

with

reacts to the poison a which are inhibited

by

but it is much less sensitive than choline acetylase which is inhi

of the poison (1).

TABLE 1. Glucose uptake (in mg/g wet weight/hr) of the rat diaphragm, and effect on it of tetrodotoxin, epinephrine and nor-epinephrine.

TABLE 2. Glycogenesis (expressed in amount of reducing sugar obtained by hydrolysis of glycogen) in the rat diaphragm, and effect on it of tetrodotoxin, epinephrine and nor epinephrine.

Epinephrine

at a concentration

on the contrary.

of 1 x 10' depresses the glucose uptake and glycogenesis

This result is in good agreement

with that of 0 . Walaas and E. Walaas

(3). In the presence of insulin, epinephrine exhibits again a distinct inhibition of the glucose uptake, 10.4 mg/g/hr being taken up by the diaphragm in presence of insulin alone and 8.1 mg/g/hr

in the presence of insulin plus epinephrine.

that of the control can be demonstrated :Vor-epinephrine chemical relationship uptake

and glycogen

unaffected

by any substance.

Thus,

The latter figure is the same as antagonism

between

both drugs

also in titro. shows an action quite

opposite to that

between them, and at a concentration production

noticeably.

increasing the glucose uptake further

of epinephrine , despite close of 1 x 10', it enhances glucose

Insulin is synergistic

with nor-epinephrine , than nor-epinephrine alone can do . There are several

studies already

published concerning

on glycolysis and blood glucose level.

comparative

and nor-epinephrine

Most of them agree in that nor-epinephrine

1/5 to 1/10 time as potent as epinephrine glycogenesis

effect of epinephrine

in this respect (4).

Now, it is apparent

is about that on

they act quite oppositely. CONCLUSION

By means of the isolated rat diaphragm, epinephrine

and nor-epinephrine

Tetrodotoxin

effect of the poison of globefish (tetrodotoxin),

on glucose uptake and glycogenesis was studied.

(1 x 10' to 1 x 10') and

nor-epinephrine

(1 x 10-`) increased, and epine

phrine (1 x 10-') decreased them. Insulin acted synergistically epinephrine, and antagonistically with epinephrine.

with tetrodotoxin

REFERENCES 1) KURIAKI, K. AND NAGANO, H.: Brit. J. Pharmarol. 12, 393 (1957) 2) LIEBECQ, C. : Biochem.J. 58, 65 (1954) 3) WALAAS, E. AND WALAAS, O.: J. biol. Chem. 195, 367 (1952) 4) VON EULER, U.S.: Nor-adrenaline, Charles C. Thomas, Springfield (1952)

and nor