Manganese is an essential trace element found in many enzymes. As it is the case of many essential trace elements, excessive level of manganese is toxic. It has been proven that excessive manganese could cause heart problems. In order to understand the mechanism of manganese toxicity in the heart, the effects of manganese on isolated rat ventricular myocytes were studied. The L-type calcium channel current was measured by whole-cell patch clamp recording mode. In the electrophysiology experiments, both 50 microM Mn2+ and 100 microM Mn2+ could effectively decrease the channel current amplitude density by 35.7% and 68.2%, respectively. Moreover, Mn2+ shifted the steady-state activation curve toward more positive potential and the steady-state inactivation curve toward more negative potential. Investigation by RT-PCR showed that the mRNA expression of alpha1C/Cav1.2 treated with manganese was decreased depending on its concentration, while the mRNA expression of alpha1D/Cav1.3 was almost unchanged. Fluo-3/AM was utilized for real-time free calcium scanning with laser scanning confocal microscopy (LSCM), and the results showed that Mn2+ could elicit a slow and continuous increase of [Ca2+]i in a concentration-dependent manner. These results have suggested that manganese could interfere with the function of the L-type calcium channel, downregulate the mRNA expression of alpha1C/Cav1.2, and thus causing long-lasting molecular changes of L-type calcium channel which have probably been triggered by overloading of calcium in myocytes.

The natriuretic peptides are a family of small peptides that activates specific NP-bound guanylyl cyclase (GC) receptors and stimulates cGMP synthesis. Three main natriuretic peptides have been identified so far: atrial (ANP), B-type (BNP) and C-type natriuretic peptides (CNP). Among them, BNP having a common core structure of natriuretic peptides, which consists a 17-member disulfide ring with a highly conserved internal sequence of -FGXXXDRIGXXSGL-, plays an essential role in the maintenance of homeostasis such as natriuresis, diuresis, vasorelaxant effect and inhibits the activation of renin-angiotensin-aldosterone system under pathological conditions. 1) Expression of the three natriuretic peptide receptors (NPR-A, NPR-B, NPR-C) has been confirmed in human and rat cardiac tissue.2) Commonly, BNP exhibits its effects by preferentially binding to the NPR-A (also known as GC-A) which is coupled to cytoplasmic C-terminal GC catalytic domain and signals via formation of cGMP. 3,4) Although some studies have shown a compensatory role for BNP in heart disease, the precise contribution of BNP to the pathophysiology of heart is poorly understood.Ischemia is one of the most common pathological conditions in many cardiovascular diseases. Apoptotic cell death has been shown to be one of the major pathological events in a variety of cardiovascular ischemic conditions such as myocardial infarction.5) As the stimuli of cardiomyocyte apoptosis, a range of stress including mild hypoxic, 6) ischemic and neurohumoral stimulation 7) has been illustrated in vitro. Particularly in several studies, hypoxia is the direct trigger and well-known stimulus of apoptosis independent of the neuronhumoral factors in various physiologic and pathologic conditions.8) Some studies have indicated that ANP and CNP inhibit vascular smooth muscle growth [9][10][11] and ANP induces apoptosis in cultured vascular smooth muscle cells, 12) which infer the negative effect of natriuretic peptides on the cardiovascular system. In this regard, the role of BNP in mild hypoxia-induced cardiomyocytes apoptosis and the possible mechanism are of great interest to explore. The present study was therefore designed to examine whether BNP influenced apoptotic cardiomyocyte death under mild hypoxia which has been proved to trigger the intrinsic mitochondrial death signaling pathway, and whether cGMP was involved in the process. MATERIALS AND METHODSPrimary Culture of Cardiomyocytes Primary culture of neonatal rat cardiomyocytes were prepared as described before.13) In brief, the ventricles of 3-d-old Sprague-Dawley rats were digested with 0.08% trypsin and 0.06% collagenase II (Sigma Chemical Co., U.S.A.). The cells in suspension were collected, washed and seeded in 24 well plates at a density of 2ϫ10 5 cells. All cells were cultured in a medium containing 85% DMEM (Invitrogen, CA, U.S.A.) and 15% fetal bovine serum. The proportion of cardiomyocytes was enriched by the preplating method. BrdU (0.1 mM, Sigma, U.S.A.) was added within the first 48 h to inhibit fibrob...

Dietary macronutrients and micronutrients play important roles in human health. On the other hand, the excessive energy derived from food is stored in the form of triacylglycerol. A variety of dietary and hormonal factors affect this process through the regulation of the activities and expression levels of those key player enzymes involved in fatty acid biosynthesis such as acetyl-CoA carboxylase, fatty acid synthase, fatty acid elongases, and desaturases. As a micronutrient, vitamin A is essential for the health of humans. Recently, vitamin A has been shown to play a role in the regulation of glucose and lipid metabolism. This review summarizes recent research progresses about the roles of vitamin A in fatty acid synthesis. It focuses on the effects of vitamin A on the activities and expression levels of mRNA and proteins of key enzymes for fatty acid synthesis in vitro and in vivo . It appears that vitamin A status and its signaling pathway regulate the expression levels of enzymes involved in fatty acid synthesis. Future research directions are also discussed.

No abstract

Both patch clamp and laser scanning confocal microscopy (LSCM) was applied to appraise the Anisodamine's cardioprotective effects quantitatively and its mechanism were studied. MTT measurement was observed cell viability and Fluo-3/AM was utilized for real-time free calcium with LSCM; ICa,Lexposed to Anisodamine was measured by whole-cell patch clamp recording technique. Our study observed that KCL-triggered calcium elevation could be decreased by Anisodamine at dose of 0.04mmol/L and 0.08mmol/L with the decreased value of 46.6%, 54.3% correspondingly. Further study of Anisodamine at 0.08mmol/L showed a marked inhibitory modulation of L-type Ca²⁺current density in a time-dependent manner with decreased ratio of (34.8±7.9) % (n=6, P<0.01), from the value of -4.474 pA/pF to - 2.882 pA/pF and accelerated Vi1/2of current inactivation curve from -14.7mV to -28.4mV and delayed Vi1/2of current activation curve from -15.6mV to -9.51mV. Our result suggests that Anisodamine conferred the cardioprotection by decreasing calcium elevation quantitatively; the likely mechanism was suggested to be responsible for inhibition of L-calcium channel.