Spontaneous rhythmic contraction-dilatasion of the blood vessel is defined as vasomotion. In the present study, a physiological meaning of the intermittent circulation by such vasomotion is considered. Since the intermittent flow by vasomotion at precapillary sphincter brings about change of the amount of erythrocyte per unit length of a capillary, as a result the degree of blood viscosity are changed. Moreover, if pressure change in a terminal arteriole is occurred by vasomotion, the distribution of local pressure in a capillary will more change, and transportation of the water is influenced. Consequently, vasomotion is related to the fluid exchange between the tissue and capillary, and the generation of lymphatic fluid. The capillary bed of skeletal muscle is chosen as a model, and the oxygen transportation is considered theoretically. If the erythrocyte which flows a capillary according to the result is intermittent, and especially a capillary network lapses into a low blood-flow state, the tissue oxygen pressure during vasomotion is higher than that at the maintain steady state of capillary flow. The intermittent flow by vasomotion is decreasing the dead angle point of oxygen transportation, and is said to make movement of the oxygen through capillary wall more efficient.

View full abstract

Actin filament dynamics in endothelial cells was observed during exposure to fluid shear stress. A plasmid encoding enhanced green fluorescent protein (GFP) fused to the amino terminus of actin was transfected into cultured bovine aortic endothelial cells (BAECs) using a liposomal method. This functional GFP-actin construct enabled observation of actin filaments in BAECs. BAECs were exposed to fluid shear stress of 2 Pa using a parallel plate flow chamber and dynamic behavior of actin filaments in BAECs expressing stable GFP-actin was observed under a time lapse fluorescence microscopy. Cytoskeletal reorganization during exposure to shear stress preceded changes in cell shape. In a typical example, dense peripheral bands located upstream side in a cell moved toward the nucleus and fine network structure of actin filaments was partly destroyed within 60 min. After 180 min, actin filaments started to form thick bundles in the whole region of the cell, followed by cell elongation to the flow direction. Changes in cell shape and cytoskeletal structure seemed to be finished around 300 min. The GFP-actin expressed in endothelial cells should reveal detailed moving process of actin filaments in endothelial cells under mechanical stimuli.

View full abstract

Silkworms that feed on mulberry leaves contain a markedly larger amount of amino acids and almost the same amount of unsaturated fatty acids in comparison with mulberry leaves. Silkworms in beginning stage of the fifth period contain a larger amount of those nutrients compared with silkworms in the final stage of it. The rheological characteristics of silkworm blood were remarkably changed during growing process of silkworm, viscosity of silkworm blood in beginning stage of the fifth period is lower than that in the final stage of it. Here, it should be noted that the rheological characteristics of silkworm blood reflect physiolosical circulation of silkworm, suggesting that the physiolosical condition of silkworm in beginning stage of the fifth period is better than that in the final stage of it. Thus, based on these results, it was found that silkworm powder could be a new health food when silkworms in beginning stage of the fifth period were used.

View full abstract