Biological actions of green tea catechins on cardiac troponin C.

Background And Purpose: Catechins, biologically active polyphenols in green tea, are known to have a protective effect against cardiovascular diseases. In this study, we investigated direct actions of green tea catechins on cardiac muscle function to explore their uses as potential drugs for cardiac muscle disease.

Experimental Approach: The effects of catechins were systematically investigated on the force-pCa relationship in skinned cardiac muscle fibres to determine their direct effects on cardiac myofilament contractility.

Propyl gallate, a strong antioxidant, increases the Ca2+ sensitivity of cardiac myofilament.

Ca(2+) sensitizers are cardiotonic agents that directly increase the Ca(2+) sensitivity of cardiac myofilament. To find a novel Ca(2+) sensitizer, we have screened a group of phenolic compounds by examining their effects on the Ca(2+)-dependent force generation in cardiac muscle fibers. We found that propyl gallate, a strong antioxidant, increased the Ca(2+) sensitivity of cardiac myofilament in a dose-dependent and reversible manner.

Knock-in mouse model of dilated cardiomyopathy caused by troponin mutation.

We created knock-in mice in which a deletion of 3 base pairs coding for K210 in cardiac troponin (cTn)T found in familial dilated cardiomyopathy patients was introduced into endogenous genes. Membrane-permeabilized cardiac muscle fibers from mutant mice showed significantly lower Ca(2+) sensitivity in force generation than those from wild-type mice. Peak amplitude of Ca(2+) transient in cardiomyocytes was increased in mutant mice, and maximum isometric force produced by intact cardiac muscle fibers of mutant mice was not significantly different from that of wild-type mice, suggesting that Ca(2+) transient was augmented to compensate for decreased myofilament Ca(2+) sensitivity.

SCH00013, a novel Ca(2+) sensitizer with positive inotropic and no chronotropic action in heart failure.

We investigated the effects of the agent SCH00013 on Ca(2+)-induced force generation in rabbit skinned cardiac muscle fibers and in vivo cardiac function in high-pacing-induced heart failure dogs. The Ca(2+)-induced force generation in skinned cardiac muscle fibers was determined at pH 6.2 - 7.

Structure and antigenicity of the mannans of Candida famata and Candida saitoana: comparative study with the mannan of Candida guilliermondii.

The chemical structure of the mannans of antigenic factor 9-expressing yeast, Candida famata and Candida saitoana, was analyzed by acetolysis and NMR. The structural study of the oligosaccharides and mannans using one- and two-dimensional NMR indicated that the mannan of C. saitoana contains a third type of beta-1,2-linked mannose unit.

Effect of vitamin B12-deficiency on the activity of hepatic cystathionine beta-synthase in rats.

The effect of vitamin B12(B12)-deficiency on the activities of hepatic methionine synthase, homocysteine methyltransferase, and cystathionine beta-synthase was investigated in rats. The rats bred from B12-deficient dams were fed the B12-deficient diets for 150 days after weaning. Growth retardation of the B12-deficient rats was already observed on day 30 and continued through 150 days.

Effect of vitamin B12 deficiency on S-adenosylmethionine metabolism in rats.

The effect of vitamin B12 (B12) deficiency on the levels of S-adenosylmethionine (SAM) in tissues and the activities of hepatic methionine synthase, methionine adenosyltransferase and glycine N-methyltransferase were investigated. The striking depression of methionine synthase activity was observed in all rats fed the B12-deficient diets with or without methionine supplementation for 150 days. The SAM level in liver was decreased by B12 deficiency.