Heart kinetic properties

Pindolol, oxprenolol, acebutolol and alprenolol are /3-blocker ISA. A weak sympathomimetic effect can be seen in the heart if almost all /3-adrenoceptors are occupied by these compounds. The advantage of ISA might be that a basal /3-adrenergic stimulus is left. In some vessel beds a reduction of the vascular activity and thereby a reduction in resistance has been observed with pindolol which might be beneficial in the therapy of hypertension. The pharmacodynamic and -kinetic properties of some frequently used jS-blocker are shown in Table 2. 

Hall, N. Addis, P. DeLuca, M. Mitochondrial creatine kinase. Physical and kinetic properties of the purified enzyme from beef heart. Biochemistry, 18, 1745-1751 (1979)... 

Saks, V.A. Chernousova, C.B. Cukovsky, D.E. Smirnov, V.N. Chazov, E.L Studies of energy transport in heart cells. Mitochondrial isoenzyme of creatine phosphokinase kinetic properties and regulatory action of Mg " ions. Eur. J. Biochem., 57, 273-290 (1975)... 

Font, B. Gautherson, D.C. General and kinetic properties of pig heart mitochondrial adenylate kinase. Biochim. Biophys. Acta, 611, 299-308 (1980)... 

Colomb, M.G. Cheruy, A. Vignais, P.V. Nucleoside diphosphokinase from beef heart cytosol. I. Physical and kinetic properties. Biochemistry, 11, 3370-3378 (1972)... 

The enzyme, which has been isolated from many species, is a tetramer of Mr 140 000. The two forms of the enzyme, the H4, predominating in heart muscle, and the M4, predominating in skeletal muscle, give rise to a family of isozymes.46,47 The amino acid composition of the polypeptide chain that constitutes the M4 form is significantly different from that of the H4 form, and the two have different kinetic properties. Despite this, the sites for the association of the subunits had to... 

N4. Nisselbaum, J. S., and Bodansky, O., Immunochemical and kinetic properties of anionic and cationic glutamic-oxaloacetic transaminases separated from human heart and human liver. J. Biol. Chem. 239, 4232-4236 (1964). 

This form may occur in anaerobic tissues, in which lactate is the end product of glycolysis. However, in vitro differences in kinetic properties of the isoenzyme may be inappropriate to explain actual physiological actions for several reasons differences in kinetic properties between LDH-1 and LDH-5 are less marked at 37°C (body temperature) than at 25°C, high intracellular concentrations of the enzyme are present, and differences in the actual ratio of ketopyruvate to enolpyruvate exist (the enol form may be the more potent inhibitor). Furthermore, the occurrence of similar isoenzyme patterns in widely different tissues with divergent metabolic goals (e.g., LDH-5 in liver and musele LDH-1 in heart and erythrocytes) points out our lack of understanding of their preeise role. 

LDH catalyzes the interconversion of lactate and pyruvate with the coenzyme NAD (see Fig. 6). This enzyme plays a fundamental role in respiration, and multiple isozymes have evolved to enable efficient production of substrate in different microenvironments. Two main subunits, referred to as heart and muscle, are combined in the functional enzyme as a tetramer, and subunit combinations range from pure heart to pure muscle. The kinetic properties of the heart and muscle isoforms are... 

It must be realised that the kinetic properties of the translocators may vary from species to species and even from tissue to tissue in the same species. One example is the relatively high capacity of the tricarboxylate translocator in liver compared to that in heart [1,19], which is related to the absence of extramitochondrial fatty, acid synthesis in heart. Another example is the high activity of the dicarboxylate translocator in liver compared to that in heart [19] which is related to the absence of gluconeogenesis in heart. 

The heart of interfacial electrochemical kinetics is electron transfer—metal to solution and solution to metal. The electron is a particle, the movement and properties... 

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