Absence Of Electrical Stimulation Research Articles

Effects of 2,4-dinitrophenol and ouavain on respiration and metabolism of separated cerebral cortex in both presence and absence of electrical stimulation.

The fact that separated mammalian cerebral cortical tissues, suitably maintained in vitro, show remarkable respiratory and metabolic responses to adequate electrical stimulation has already been published frequently (1) ; recently it was shown that such respiratory and metabolic responses to adequate electrical stimulation were dependent only on the concentration of external sodium, approximately in Michaelis Menten fashion, but potassium by itself was inert to this metabolism, and calcium was independent of such responses (2). Meanwhile, a number of studies are being made everywhere at present in order to elucidate the exact mechanism of linkage between active cation transport and metabolism. One of the experimental approaches to the mechanism by which the energy from metabolism is supplied to active transport, would be to examine the action of metabolic inhibitors. It seems to be necessary to investigate whether or not the respiratory and metabolic responses stated above have any connection with the active transport; therefore, the effects of ouabain and 2, 4-dinitrophenol on the respiratory and metabolic responses of a rat's cerebral cortical slices to electrical stimulation have been studied in this paper.

THE EFFECTS OF SODIUM, POTASSIUM AND CALCIUM ON METABOLISM OF RAT’S CEREBRAL CORTICAL SLICE WITH OR WITHOUT ELECTRICAL STIMULATION

A wide study, extending even to analysis in homogenates and subcellular fractions, is now being made in order to elucidate the exact mechanism of linkage between active cation transport and metabolism. Many wonderful achievements and hypotheses seem to have been published; nevertheless, the exact mechanism is still obscure. The fact that separated mammalian cerebral tissues, suitably maintained in vitro, show remarkable metabolic responses to adequate electrical stimulation has been explored mainly by McIlwain and his colleagues. Their comprehensive studies concerning this phenomenon have led to many valuable findings, and that concerning ganglioside may be especially excellent (1-3). However, at the present stage, it cannot be said that the biochemical origin of these metabolic responses and its physiological roles are clear. In addition, except for their achievement, other achievements along this line are still very few and some differences in the results also can be observed. From the point of view of the present studies concerning active transport and metabolism, there is even more of a necessity for studies along this line. Therefore, we have taken a somewhat different experimental procedure to manifest the role of external sodium in metabolism of separated mammalian cerebral cortical tissue in both the presence and absence of electrical stimulation in correlation to the effects of potassium and calcium.

Pharmacological study of the venom of the gastropod Conus magus

Venom extracted from posterior regions of the venom duct of C. magus Linné was lethal to mice and produced a contracture of isolated skeletal and smooth musculature of the rat in the absence of electrical stimulation. The effect was sustained and the musculature became paralysed in the contracted state. With electrically stimulated or strongly curarized rat phrenic nerve-diaphragm preparations the contracture elicited by a certain concentration of venom was of similar magnitude and time course to that elicited in unstimulated or non-curarized preparations. For a period, the length of which was related to venom concentration, the diaphragm was capable of responding with a twitch to electrical stimulation. The heights of successive muscle twitches declined progressively and eventually the musculature became refractory to stimulation. Tubocurarine, isotonic K 2SO 4, neostigmine or acetylcholine had no observable effect on the sustained contracture elicited by the venom. Posterior duct venom increased the strength of contraction of the musculature of the ventricle of the toad but decreased its rate of contraction. Cardiac musculature was not paralysed by the venom at concentrations tested. The effects produced by the venom in skeletal, smooth or cardiac musculature could be reversed by washing out the venom.