The action of acetaldehyde on the intracellular electrical activities of the guinea-pig taenia coli

The effect of acetaldehyde on the membrane potential and the membrane resistance of the guinea-pig taenia coli has been studied with an intracellular recording technique. Application of acetaldehyde in the concentration of between 5 and 20 mM produces reduction or elimination of the spontaneous spike activity and hyperpolarization of the membrane. The amplitude and the rates of rise and fall of the action potential are reduced by the drug. The duration of the spike is slightly prolonged. Acetaldehyde also reduces the amplitude of the evoked action potential produced by externally applied cathodal stimulation in twice hypertonic solution. Electronic potentials induced by anodal current are reduced both in size and time course by acetaldehyde during the stage of hyperpolarization.

Effects of acetaldehyde on electrical and mechanical activities of guinea-pig taenia coli

The effect of acetaldehyde on the electrical and mechanical activities of the isolated segment of taenia coli from guinea-pigs has been studied using a sucrose-gap method. Application of acetaldehyde produces relaxation of the muscle, which is accompanied by reduction or cessation of spontaneous spike activity and hyperpolarization of the membrane. The hyperpolarization becomes smaller with lowering the temperature. These actions of acetaldehyde are not modified by adrenergic and cholinergic receptor blocking agents nor by tetrodotoxin and ouabain. Acetaldehyde also reduces the evoked activities produced by KCl, BaCl2, acetylcholine or electrical stimulation. The nonadrenergic inhibitory junction potential is reduced by acetaldehyde. When external Ca++ is replaced with Sr++ or Ba++, the action of acetaldehyde is suppressed. Addition of Mn++ eliminates the action of the aldehyde. Acetaldehyde relaxes the muscle when administered after fully developed membrane depolarization induced by K2SO4.

Demonstration of intracytoplasmic glycogen of megakaryocytes and blood platelets by means of the periodic acid-thiocarbohydrazide-silver proteinate method

The glycogen of megakaryocytes and blood platelets has been investigated in glutaraldehyde and osmium tetroxide fixed tissues by the periodic acid-thiocarbohydrozide-silver proteinate method (PA-TCH-SP). The PA-TCH-SP method involves the staining of intracytoplasmic glycogens more densely than the routine lead citrate method. Glycogen having a mean particle diameter of 21.1 nm has been shown localizing in the matrix of mature megakaryocytes, while that of glycogen in the platelets was 26.2 nm. The staining pattern of the glycogen in blood platelets was classified into three groups according to staining intensity. It is found that the PA-TCH-SP method is a very suitable one for the demonstration of intracytoplasmic glycogen from the viewpoints of reaction specificity, reproducibility, fineness of reaction products, sufficiency of electron density, and experimental cost. This method is also a very useful one for differentiating intracytoplasmic glycogens and ribosomes.