Biomedical subjects
I Syrový
Publications and source records attributed to I Syrový.
Atrial and ventricular myosin ATPase--divergence with increasing animal species size.
Myosin was isolated from mouse, rat, rabbit, pig and bovine atrial and ventricular myocardium and Ca2+-ATPase activity was examined. In the mouse the ATPase activity of myosin was the same in atrial and ventricular myocardium. In larger animal species, the activity of atrial myosin ATPase was higher than that of ventricular myocardium and the larger the animal species the greater the divergence between the activities of atrial and ventricular myosin ATPase. The relevance of these observations to regulation of heart contractility is discussed.
Separation of muscle proteins.
This review covers various methods used in the separation and isolation of individual muscle contractile proteins. It is shown which methods have been most useful for the separation of contractile proteins and their fragments and in extending our knowledge of muscle biochemistry and physiology.
Changes in rat ventricular myosin in old age.
Myosin was isolated from rat ventricular myocardium, and its properties were compared in adult and very old animals. Ca2+ -ATPase activity of ventricular myosin was found to be lower in very old animals as compared with adult ones; K+ -ATPase activity, however, does not change with the aging process. Neither were there any differences between the two age groups in the pattern of ventricular light chains of myosin.
Atrial and ventricular myosin during development and senescence of the rat.
Myosin was isolated from rat atrial and ventricular myocardium and examined during post-natal development and senescence. The post-natal increase of Ca2+-ATPase activity of myosin from rat atria did not run in parallel with changes of ATPase activity of myosin from the ventricles. Ca2+-ATPase of both atrial and ventricular myosin was activated at pH 9.5, when compared with the assay performed at pH 7.5. The myosin light-chain subunits in the ventricles were different from the light-chain subunits in the atria, when characterized by SDS-polyacrylamide gel electrophoresis and the pattern remained practically unchanged during development, with the exception of atrial myosin from new-born and very old rats which contained an additional protein of low molecular weight.
Effects of temperature on rat and mouse cardiac myosin ATPase activity during development.
Myosin was isolated from rat and mouse ventricular myocardium and examined during development at stages with known composition of myosin isoenzymes. The ATPase activity and its temperature dependence is the same in one-week-old and adult mouse ventricles. In rat heart myosin, the ATPase activity is low 18 days prenatally, high in 3-week-old animals and declines towards adulthood. ATPase activity of heart myosin from rat foetuses is more temperature dependent than that of three-week-old animals. These results strongly suggest that adaptation of the heart to development differs in the mouse and the rat and that the properties of mouse V1 isoenzyme do not change at the studied periods.
[Functional importance of the existence of myosin isoenzymes].
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The relation between myosin Ca2+ - and K+ -adenosine triphosphatase activity of heart muscles in mammals of different size.
1. The influence of KCl and CaCl2 on ATPase activity of ventricular myosin of the mouse, rat, rabbit and cow, the temperature dependence of ATPase and the effect of pCMB treatment and tryptic digestion on ATPase activity of these myosins were studied. 2. Ca2+ - and K+ -ATPase activities of myosins were inversely related to body size of the animal species; when K+ -ATPase activities were measured in the absence of EDTA, the body size/ATPase dependence was only slightly apparent. 3. The influence of temperature, the effect of pCMB and the influence of tryptic digestion on Ca2+ - ATPase activity distinguished the compared myosins. 4. There was a marked alteration of the effect of myosin treatment with pCMB or trypsin on K+ -ATPase activity of these myosins and in this case differences in K+ -ATPase activities were less pronounced.
Comparison of actomyosin and myosin from rat muscles with marked differences in the ratio of fast oxidative glycolytic and fast glycolytic muscle fibres.
Actomyosin and myosin were isolated from rat fast muscles, differing in the percentage of fast oxidative glycolytic and fast glycolytic fibres. The dependence of actomyosin ATPase activity from these muscles on the pH corresponds to the previously found dependence of myofibrillar ATPase on the pH, followed histochemically. The myosins isolated from the tensor fascia latae muscle (fast glycolytic) and extensor digitorum longus and tibialis anterior muscles (predominantly fast oxidative glycolytic muscles) differ in the effect of mild acid pre-incubation on myosin ATPase activity. They do not contain the same amount of LC3 and also tryptic peptides of these myosins display a slightly different pattern, as revealed by SDS gel electrophoresis.
Induction of extrajunctional acetylcholine sensitivity of rat EDL muscle by peptidic component of peripheral nerve.
The induction of extrajunctional ACh-sensitivity was studied electrophysiologically 4 days after implantation of segments of the sciatic nerve, segments of dorsal and ventral spinal roots and silastic plates, containing some components of peripheral nerve onto surface fibres of innervated rat extensor digitorum longus muscle. It has been found that extrajunctional ACh-sensitivity can be induced by a piece of rat sciatic nerve and by peptidic material of about 8,000 and 10,000 mol. wt. No sensitivity was induced by segments of ventral and dorsal roots, by a piece of rabbit sciatic nerve and by rat sciatic nerve sectioned 7 days prior to implantation. The active nerve fractions lost its inducing potency after pepsin pre-treatment and irradiation with UV-light. Peripheral nerve probably contains some specific factor, peptidic in nature, which is able to induce the ACh-sensitivity of muscle fibre membrane.
Proteolytic digestion patterns of myosin from new-born and adult fast, slow, and mixed skeletal muscle.
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Light chains of myosin from diaphragm of rabbit embryos and adult rabbits.
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Do peripheral nerves contain a factor inducing acetylcholine sensitivity in skeletal muscle?
A crude extract of the sciatic nerve, eluate of dialyzed nerve extract or 2 folin-positive sephadex fractions induced acetylcholine sensitivity of extrajunctional regions in extensor digitorum longus muscle fibres of the rat, when released from silastic plates implanted for 3--4 days onto the muscle surface.
Changes in light chains of myosin during animal development.
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Polymorphism and specificity of myosin.
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Characterization of cardiac myosin from rabbit embryos and adult rabbits.
1. Ca2+-ATPase of myosin and electrophoretic pattern of light chains of myosin were investigated in cardiac muscles of 22-day-old rabbit embryos, new-born and adult rabbits. 2. Ca2+-ATPase activity was found to decrease during development and in contrast to that of adult rabbit, cardiac myosin prepared from 22-day-old embryos, is stable on exposure to pH 9.5. 3. Myosin from the cardiac muscle of rabbit embryos reveals light chains of both fast and slow types, that from adult animals, however, reveals light chains of the slow type only. 4. These studies suggest that unlike the cardiac muscle of adult rabbit, cardiac muscle of rabbit embryos contains both fast and slow types of myosin.
Differentiation of myosin in soleus and extensor digitorum longus muscle in differnt animal species during development.
CA2+-ATPase activity and light chains of myosin prepared from fast and slow muscles of rat guinea-pig and rabbit were studied during development from embryonic to old age to establish further correlation with the well-known developmental changes in contraction properties of these muscles. The changes involve the slow soleus muscle much more than the fast extensor digitorum longus muscle. Myosin-ATPase activity of the soleus muscle before or at birth is higher than in the muscle of adult animals. Myosin from the soleus muscle of embryos or newborn animals reveals light chains of myosin of both fast and slow type (with a preponderance of light chains of fast type in 26-days-old rabbit embryos). During postnatal development the amount of light chains of the fast type decreases, that of the slow type increases. Myosin from the soleus muscle of adult animals contains only light chains of the slow type. However, myosin from the soleus muscle of 30-months-old rats exhibits high myosin ATPase activity and contains light chains of myosin of both slow and fast type as in perinatal development. This is in agreement with the shortening of contraction time observed in this muscle in very old age. Thus developmental differentiation of myosine in the soleus muscle is followed by a trend of levelling out of the differences between fast and slow muscles of senescent animals. No such "biphasic" development is observed with respect to the fast extensor digitorum longus muscle.
Functional transformation of fast posterior latissimus dorsi muscle by "slow" nerve implanted in newly hatched chickens.
1. Contraction properties and the activity of Ca2+ - ATPase were investigated 2 and 5 to 6 1/2 months after transposition of the fast posterior latissimus dorsi muscle (PLD) to the other side in newly hatched chickens. At the same time the muscle was cross-innervated by the nerve originally supplying the slow anterior latissimus dorsi muscle (ALD). 2. The mean isometric twitch contraction time of these transposed, cross-innervated PLD muscles in the 2-month-old and 5 to 6 1/2-month-old groups was 61.6 +/- 4.2 msec and 72.5 +/- 10.8 msec respectively. When compared with values obtained in control PLD and ALD muscles (21.9 +/- 0.6 msec and 107.7 +/- 5.6 msec), contraction time was significantly prolonged by this procedure. 3. Ca2+ - ATPase activity was also found to change towards the slow muscle (activity in control PLD was 0.600 micronmoles Pi/mg myosin/min, in the transposed, cross-innervated PLD 0.462 and in control ALD muscle 0.156 respectively). 4. Foreign innervation may thus induce changes in functional and biochemical properties even in muscles considerably different in structure and function, if transformation is allowed to take place at a sufficiently early stage of development. The muscle transposition itself, by introducing the element of muscle dedifferentiation and regeneration, probably assists the transformation process by making the muscle more plastic to the neural influences.