Effects of bioglycans isolated from birch fungiinonotus obliquus on electric activity of venous sinus cells in frog heart

Abstract

Bioglycans isolated from chaga in a concentration of 0.0001% reduced frequency of action potential in venous sinus cells of frog heart during the first 15-30 rain of exposure, then this parameter increased by 10% per hour over 3.5 h, and was 41+3 min -1 from the 4th to the 20th hour of incubation. The frequency of action potentials in heart strips in the chaga extract was 40% higher than in Ringer's solution. The effect of chaga bioglycan is probably associated with adsorption on myocyte membranes. Binding of Ca 2+ to bioglycans observed during the first 30 min inhibited effiux of intracellular Ca 2+. Key Words: chaga; bioglycans; action potential; pacemakerChaga (birch fungi Inonotus obliquus) are used in Russian medicine for centuries. The preparation Befungin produced from these fungi since 1955 normalized blood content of cholesterol and improved functions of the cardiovascular system [2,4] [4]. However, the mechanisms of this effects remain unclear.Here we studied the effects of chaga bioglycans on spontaneous rhythmic activity and membrane potentials of venous sinus cells of frog heart. MATERIALS AND METHODSExperiments were performed on sinoatrial strips isolated from grass frogs Rana temporaria (n=27) in February-March. After destruction of the spinal cord, the animals were decapitated, and the heart was immediately removed. Two preparations from the right and left parts of the sinoatrial ring were produced. The effects of 24-h incubation with bioglycan were studied on the right part. The left part was incubated in control Ringer's solution containing (in raM) 112 NaC1, 1.9 KC1, 0.9 CaC12, and 2.4 NaHCO 3 (pH 7.5-7.7 was Laboratory of Physiological Researches, Department of Biotechnology and Molecular Immunology, Institute of Physiology, Komi Research Center, Ural Division of the Russian Academy of Sciences, Syktyvkar maintained by aeration with air and Tris-maleate-NaOH buffer). The preparations were perfused at 2 I+2~ Chaga fungi were gathered in Syktyvkar environs in August. Air-dried raw materials were preliminary treated with methanol and chloroform to remove lowmolecular-weight admixtures. Bioglycan precipitate was obtained after 5-h extraction with hot distilled water (70~ followed by ethanol precipitation [3]. Bioglycans were isolated by centrifugation, dissolved in water, dialyzed, and lyophilized (total yield 1.6%). Glucose was assayed after hydrolysis with 2 M trifluoroacetic acid at 100~ for 3 h [3]. Bioglycan was added to standard Ringer's solution to a concentration of 0.0001%.Action potentials (AP) were recorded intracellularly with glass microelectrodes (initial resistance no less than 40 M~) and imputed into a C1-114"1 oscilloscope coupled with an H-3030 automatic recorder. The results were statistically analyzed and presented as mean• error. The differences were significant at p<0.05 [1].

Chemical and medicobiological properties of chaga (review)

“…Golovko [65] studied the effect of bioglucans isolated from birch tree on the electrical activity of cells from the frog heart venous sinus. It was established that a 0.0001% solution improved the excitability properties of cell membranes, the effect being comparable with that of a hypocalcium solution (except that the positive chronotropic action of bioglucans was 50 -100 times longer).…”